die joernaal vir die vrugtebedryf in suid-afrika … · at the time of writing, redrafting of...

D I E J O E R N A A L V I R D I E V R U G T E B E D R Y F I N S U I D - A F R I K A F E B / M A R C H ‘ 2 0

1FEB/MARCH 2020 | SA FRUIT JOURNAL

At the time of writing this, we had been drifting in and out of darkness (literally). We were even faced with the grim prospect of flouting tradition by having to braai our favourite Christmas cut of meat, thanks to loadshedding.

This brought to mind the significance of light and darkness in our lives.

On the lighter side at the time, our Miss SA Zozibini Tunzi, had just clinched the Miss Universe crown; and Trevor Noah’s Trevor Noah: Son of Patricia and Charlize Theron’s outstanding performance in Bombshell had earned them respective nomi-nations for the Critics Choice Awards (Charlize was nominated in the Best Actress category).

And veering towards what represents darkness for SA, these come to mind: our persistently high unemployment rate, policy and structural gaps around our SOEs, economic uncertainty regarding land reform, and, of course, the debilitating drought. At the time of writing, redrafting of section 25 of the consti-tution that includes the property clause, had been referred to traditional leaders for comment, after which the public would have their turn, over three weeks in January. The process would conclude at the end of March.

But our industry’s growing production, despite significant challenges, remains a huge boon. Add to that the fact that our fruit largely enjoys geographically expansive production areas, which (in many cases) allows for challenges in one region to be offset by good conditions in another. Advancements in technology also present an increase in opportunities to innovate, create jobs and upskill our industry staff.

Though, sustained success remains a pipedream in the

absence of genuine collaboration. Therefore, it’s truly heartening to see a marked increase in grow-er partnerships – joining hands regardless of race and socio-eco-nomic standing – in the name of effectiveness and economic viability.

The featured article on the recent land symposium that focusses on social development, gives an honest account of brokers’ gripes, victories and a never-say-die drive to move agriculture forward. Then there’s the article on the sterling performance of our work-ers in the Berg River table grape region; and inspiring stories on succession and transformation from our colleagues in citrus. May these, and the rest of the features, make for engaging content.

We hope that Finance Minister Tito Mboweni’s Budget Speech holds good news for our farmers, in the form of a generous allocation of much needed funds for drought relief.

And, may our colleagues attending Fruit Logistica Berlin have meaningful engagements that will secure substantial deals for our dynamic industry. This, while flying high the SA flag.

So, in general terms, light (even in small quantities) certainly has more of an impact than darkness. Just take the scenario of striking a match in a dark room to light one candle – an experi-

ence South Africans have become all too familiar with, but not in a good way.

The fruit industry is a certain source of light in agricul-ture, with its growing production, relentless engage-ment with government to secure favourable trade

agreements, and the indomitable spirit among

EDITORIAL

Catherine Milward-BridgesEditor: SAFJ

Ignatius Vlok | 082 331 2127 | [email protected]

Opinions expressed in advertisements and promotional articles are not necessarily those of the SA Fruit Journal.

We do not accept responsibility for damage or injuries which may arise from possible inaccuracies. All rights reserved.

None of the content may be used in any other media without the prior consent of the SA Fruit Journal (Pty) Ltd.

SA FRUIT JOURNAL SSN: 1683-4577

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Light and darkness

our growers, to keep on keeping on. ✤

2 SA VRUGTEJOERNAAL | FEB/MAART 2020

ELKE UITGAWEEVERY ISSUE

BEDRYFSNUUSINDUSTRY NEWS

SA Fruit Journal Board of Directors 4Foreword 5At the kitchen table:Cool summer drinks 86The last word:Henk Griessel 88

CITRUS GROWERS’ ASSOCIATION (CGA) Succession: Eric Nohamba 30Transformation: economic growth 31Citrus Academy: Driving skills development,one short course at a time 33Citrus Academy: entrenching e-learning 35CGA alms add zest to Klouter Kabouter 36Satsuma production in SA 38CGA cultivar brief: rootstocks from Florida 40River Bioscience brief: investing in the future 40

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FPEF Export - a collaborative effort 6

HORTGRO Sainsbury's: SA Retailer of the Year 9Transforming agriculture together 10A whole lot of Saul 14CA facility turns one 16SA's prune undustry relishes signs of economic growth 18Can prunes reverse bone loss? 20Stone fruit field day 22Deciduous fruit winners 2019 23

SOUTH AFRICAN TABLEGRAPE INDUSTRY (SATI) Bergrivier-werkers blink uit 24SATI - First crop estimate: 2019/2020 season 27

CONTENTS


VOLUME 19 | PART 2

SAFJ (SA Fruit Journal) is also available inelectronic format on our website.

SAFJ (SA Vrugtejoernaal) is ook elektronies beskikbaar op ons webtuiste.

www.safj.co.za

RESEARCH ANDTECHNOLOGY

HORTGRO SCIENCEPro-Hort drives cultivar evaluation 44Impact of carton liners 46Bakgatboord Series: Bestuis farm 52

CITRUS GROWERS’ ASSOCIATION (CGA) Citrus FCM management system: Update for 2020 59

CITRUS RESEARCH INTERNATIONAL (CRI)Extension briefs for February and March 60The effect of non-permanent netting on mandarin fruit 67Irrigation of citrus trees - a practical approach 72Do smaller navel-ends mean lower pest levels? 80

SOUTH AFRICAN TABLE GRAPE INDUSTRY (SATI) Chemical control of male Margarodes prieskaensis 54

OLIVESOlive seed wasps in cultivated olives - Possible threat 84


Anton KrugerCEO, FPEF

Konanani LiphadziCEO, Fruit South Africa

SAFJ BOARD OFDIRECTORS

Anton RabeExecutive Director, HORTGRO

CGACITRUS GROWERS’ ASSOCIATION

PO Box 461, Hillcrest 3650 • Tel: 031 765 2514Fax: 031 765 8029 • [email protected]

www.cga.co.za

SAFJ SHAREHOLDERS

SATI - SOUTH AFRICAN TABLE GRAPE INDUSTRY

63 Main Street, Paarl 7646 • Tel: 021 863 0366 [email protected] • www.satgi.co.za

FPEF - FRESH PRODUCEEXPORTERS’ FORUM

Private Bag X5, Century City 7441Tel: 021 526 0474 • Fax: 021 526 0479

www.fpef.co.za

HORTGROTel: 021 870 2900 • Fax: 021 870 2915

258 Main Street, Paarl • PO Box 163, Paarl [email protected] • www.hortgro.co.za

Gloria WeareCGA 031 765 [email protected]

Elise-Marie SteenkampHORTGRO 021 870 2900

[email protected]

Tshidi RamabuCRI 013 759 8013

[email protected]

Carmé NaudéHORTGRO 021 870 2900

[email protected]

Clayton SwartSATI 021 863 0366

[email protected]

Claudia WalklettFPEF 021 526 [email protected]

CONTRIBUTORS

Willem BestbierCEO, SATI

Justin ChadwickCEO, CGA


FOREWORD

Here we are a couple of months into 2020 already. Towards the end of 2019 – as is the case with almost every year – one often hears, “I can’t believe that it is almost the end

of the year”. And it seems as if the speed of everything just keeps increasing, which sometimes overwhelms us.

The new buzzword is 4IR – the Fourth Industrial Revolution – just adds to the perception that “everything is moving faster”. The 4IR is certainly perceived and experienced differently by the various generations – the Baby Boomers (born between 1944 and 1964), the Gen X/IGen (born between 1965 and 1979), Gen Y/Millennials (born between 1980 and 1994), Gen Z (born between 1995 and 2012), and Gen Alpha/Modern Generation (born from 2013). These dates are approximate with some over-laps, because there are no real standard definitions for when a generation begins and ends.

Each generation’s world view is/was shaped by world events plus technological, economic and social tendencies. These, in turn, have an impact on workplace attitudes.

With these developments, some jobs have become obsolete; some prominent examples which can be well remembered by the Baby Boomer generation are the telephone exchange/switchboard operators, where red and black chords were used to connect two telephones and they were the people through which telephone calls were connected; typist "pools" in com-panies where managers wrote reports and letters that were sent to these typists to type. Then they were returned to the writer (or as it is called nowadays,"the document owner") who would proofread the document before signing and sending it to the mail division in the company, from where postage stamps were placed, which was then mailed off. Some advancements in the area of communication included telex machines and operators, and dictaphone recorders and typists.

And guess which generation I belong to!

Some people view these de-velopments and differences as threats, while others see them as challenges and opportunities.

In our industry, some examples of fairly recent challenges which were transformed into opportu-nities are the development and implementation of the electronic documentation to manage exports:

• the e-Cert project: the platform allows exporters to apply for phytosanitary certificates online

• the TITAN tablet technology developed and implemented to capture packhouse information

• Agri-HUB, which provides near real-time shipped information for exported fruit to enable exporters to make marketing decisions.

On production level, there are numerous examples where the latest technology is being used to ensure addressing climate change, continuous improvement of operations, efficiencies and quality produce in order to remain internationally competitive, and improving their role in providing food security.

The initiation, development and implementation of such "tools" are testimonies of the realisation that we are in an industry that requires vision, a long-term view and a can-do attitude. The development of most of these initiatives was funded by industry, with a view that it should over time become self-funded, but at the onset it was – and still is – as investments rather than costs.

Even in the research field in our industry, we see somewhat of a differentiation between pre-harvest and postharvest research. The (fairly) new name for these activities is: Research, Develop-ment and Innovation.

Whilst the importance of technological advancement is acknowledged, it should be kept in mind that people are still needed to perform these activities. Human relations (HR in this context, thus is also cru-cial for the success of the 4IR).

A wise person once said that in order to be effective in this context, the following should always be kept in mind: "High tech necessitates high touch". ✤

4IR and HRAnton Kruger

CEO, FPEF

6 BEDRYFSNUUS | FEB/MAART 2020

In fact, the Department of Trade, Industry and Competition (dtic) has reported impressive figures in terms of SA's collective income generation from successfully concluded transactions at Fruit Logistica Berlin.

At the core of the industry’s export modus operandi lies the non-nego-tiable requirement for effec-tive communication, bona fide collaboration and intentional accountability. Without these levers our world-class fruit may not even enter the highly com-petitive international target markets.

Export is essentially the lifeblood of SA’s fruit

industry, which ships more than 60% of its produce to approximately 110 countries world-wide. Amongst the member countries in the Southern Hemisphere Association of Fresh Fruit Exporters (SHAFFE), SA holds top position in terms of export volume. This makes the country

a significant contender in the industry. But fruit export is no even terrain – the goal posts could be moved at any given time, with a periodic increase in the number of hoops to jump through, thrown in.

Therefore, as a strategic safeguard, as well as to enhance efficiency, the fruit industry has

ANTON KRUGER (CEO: FPEF)

Once again a delegation from the SA fruit industry descends on the Fruit Logistica Berlin site in the month of February. But this is hardly a jet-setting escapade. Fruit Logistica Berlin is one of several strategically chosen exhibitions to attend, as they align with the industry’s market access and market development agendas.

Like any significant achievement,

SA’s fruit export success has a backstory of note.

7FEB/MARCH 2020 | INDUSTRY NEWS

established a Fruit Desk at the Agricultural Business Chamber (Agbiz). Its main aim is to ensure that industry-related matters like policy, regulations and market access are addressed effectively with the relevant government entities, through established structures.

Like any significant achievement, SA’s fruit export success has a backstory of note. The industry has meandered a long journey to achieve its current status in the international arena, and is fighting tooth-and-nail to retain its position and to expand into new markets. Since deregulation in October 1997 – when legislation allowed other exporters and agents into the fresh fruit industry for the first time – fruit export volumes have grown signifi-cantly. And in 2001 Fruit SA was established as a joint initiative, to serve as a representative umbrella body for the various industry associ-ations. Today, it comprises the Citrus Growers’ Association of Southern Africa (CGA), SA Table Grape Industry (SATI), HORTGRO, SA Subtropical Growers Asso-ciation (Subtrop), and the Fresh Produce Exporters’ Forum (FPEF).

But with a marked increase in ex-porter numbers came the need for clear criteria.

Effective communicationDriven by effective communication, the fruit export business process hinges on a five-stage sequence that is critical to overall success.

1. Pre-season planning with producers and exporters• takes place months before the start of the season• looks at market trends• ensures adherence to regulations (especially changes) • includes gathering of intelligence around buyers’ and agents’ fruit preferences.

2. Sourcing fruit and contracting with suppliers and service providers• This is when fruit is obtained from relevant sources, for efficient market supply.

3. Marketing of fruit• The exporter has to match fruit supply with customer demand – a juggling act.

• Through effective communication, exporters relay critical information regarding fruit export consignments to relevant role-players in the chain.

4. Operations management• Effective communication is vital in the opera-tions process, which includes planning, setting standards, reporting, interpretation of analysis, decision-making and review.

5. Reflective analysis • A reflective look at performance in the previ-ous season is critical to future success.

CollaborationIf not for the continued collaboration between the associations that comprise Fruit SA, the industry would be walking a rather tenuous line in this highly competitive arena.

As for export, the FPEF maintains the industry’s competitiveness by:• ensuring SA exporters’ compe-tence, for continued international support• promoting SA effectively against competitor export countries• operating in a private-public-partnership approach between

government and industry• safeguarding a stable environment for export-ers and producers• helping to drive industry transformation.

AccountabilityThe FPEF ensures accountability on the part of exporters, who are obliged to comply with cer-tain requirements, in order to acquire and retain accredited membership status with this essential industry regulatory body.

Export and market access are mutually inclu-sive – you just can’t have the one without the other. The industry’s continued innovation, job creation and ability to contribute towards food security are all super-dependent on ongoing market access. Therefore, continued effective engagement with the dtic, the Department of Agriculture, Land Reform and Rural Develop-ment (DALRRD), and the Department of Science and Innovation (DSI) is mandatory for sustained industry success. ✤

Export and market access are mutually

inclusive – you just can’t have the one without the other.


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• The Beautiful Country, Beautiful Fruit campaign was launched in 2009 with a pilot campaign on plums. It was rolled out to peaches, nectarines, apples and pears the following year, and has since run in UK retailers, the media and on social media.

• The season begins with stone fruit from November through to May and top fruit from April through to October.

• Hortgro also runs a market develop-ment campaign in Germany, a number of other markets and a domestic promotion in SA.

• Expected total stone fruit export volumes for the 2019/20 season indi-cate an increase of 17% on nectarines, 6% on peaches and 15% on plums. More detail is available on request. ✤

SAINSBURY'S SA Retailer of the Year

Left - front: Jacques du Preez,

Hortgro General Manager: Trade

and Markets; Jessica Graham,

Sainsbury’s Stone Fruit Buyer;

Anabel Penela, Sainsbury’s Stone

Fruit Technical Manager; and

Katarina Jasicova, Supply Chain

Analyst: Stone Fruit and Avocados.

Back: André Smit, Hortgro Stone

Chairman, and Daniël Theron,

Hortgro Stone Vice Chairman.

Sainsbury’s were presented with the Stone Fruit Retailer of the Year award after a strong 2018/19 season and continued support for the South African category.

Every year SA growers’ association, Hort-gro, presents the prize to one retailer for exceptional results and collabora-tion during the campaign to promote southern hemisphere stone fruit.

Jacques du Preez, General Manager: Trade and Markets at Hortgro said, “Sainsbury’s have con-sistently supported the campaign and achieved growth, regardless of a difficult season due to the drought in SA. We are delighted to present Sainsbury’s with the award this year.”

The retailer promoted South African stone fruit on sainsburys.co.uk and sainsburysmagazine.co.uk through recipe videos, MPUs and ban-ners, and included full-page advertorials in their consumer magazine.

Stone Fruit Buyer for Sainsbury’s Jessica Graham said, “The stone fruit team and I are thrilled to receive this award.”


Despite navigating an onslaught from an army of grain chinch bugs, the 450 delegates listened for more than 10 hours to stories of success, challenge,

hope, faith, frustration and even despair. The Minister of Agriculture, Land Reform and Rural Development, Thoko Didiza was also amongst the invited guests.

It was clear that all SA farmers – regardless of race and creed – share the same common goal: to get on with farming (#ForTheLoveofAgricul-

ture, as Ivan Meyer, Western Cape Minister of Agriculture likes to say).

The more cynical among us would argue that white farmers are riding the transformation wagon out of self-interest. But the land sym-posium, which was also attended by some EFF members, reframed what is really happening at gumboots level in SA orchards: black and white farmers are transforming agriculture them-selves. When they mounted the podium to share their journeys, many delegates were seen dabbing away tears. Farming (land) is a deeply emotional issue, and it’s certainly not for the fainthearted. The message was clear: we can-not let agriculture fail. SA’s agricultural sector is pivotal in ensuring food security. The sector employs thousands and is an important cog in the economic wheel. It also brings much-need-ed rural stability.

The Ceres land summit was the follow-up of the Bela-Bela conference that was organised by Landbouweekblad last year.

Chris Burgess, the Landbouweekblad editor, said that the agricultural story was told for the first time at Bela-Bela. And instead of a litany of failures, stories were heard of extraordinary successes, great partnerships, and of South Africans finding each other and building a common future.

Vice-chairman of the Witzenberg PALS, Pieter du Toit, said that when they launched the

TRANSFORMING AGRICULTURE

togetherSuccessful partnerships between farmers – both commercialand emerging black – was the focus of the recent Landbou-weekblad-Witzenberg-PALS (Partners in Agri Land Solutions) land symposium held in the Koue Bokkeveld, outside Ceres. The event drew farmers from across SA.

Georgie Hewitt and Raymond Koopstad, another successful farming partnership

between La Vouere and Verdun, outside Ceres

ELISE-MARIE STEENKAMP AND CARMÉ NAUDÉ


initiative five years ago they dreamed of building a community that everyone could be proud of: “A community that could rec-tify the wrongs of the past, while baking a larger bread to keep food on the table.”

Du Toit said that for any land initiative to be a success, all the stakeholders – local, provincial and national, including farmers and communities – had to be involved.

The PALS framework, “represents a radical departure from past land reform initiatives and is based on sound business principals, mentor-ship and training of emerging black farmers to become successful commercial farmers.” It is also based on the National Development Plan (NDP) principles “and lessons learned from previous unsuccessful models”. While the initial focus had been on black land ownership, it currently includes other opportunities for black entrepreneurs in agricultural value chains, such as packhouses, cold storage and marketing.

Struggles with government departments that hamper trans-formation were a common thread throughout the day. Several speakers fingered corruption as an obstacle in land reform and transformation. “Roles within the government should be clearly identified. Which departments are responsible for what, and that should be communicated to the public,” says Rossouw Cillié, CEO of Laastedrif Farming. “Confusion around who is responsi-ble for what causes massive delays from the government, which plays a vital part in the progress and development of agriculture in this country. We cannot do everything ourselves, we need the government to step up their game. Food security and socio-eco-nomic stability are at stake.”

From a macro-economic perspective, SA does not look good and

President Ramaphosa should declare a national state of economic emergency, says Hendrik du Toit, Investec Group CEO, who jetted in from London for the summit. Du Toit said that as a practitioner of the “dismal science of economics”, it was wonderful to see people who change real things. “What you are doing is amazing. If we could bottle the stories we heard here today, and show them to the world, the investment will come.

“Our government has been indecisive. Since 2007, we have had a leadership structure that did not lead the country. People were more interested in their back pockets than doing their jobs. That is hopefully over. The world is a tough place when you are in a developing country that needs help and support. You don’t have a choice but to do it yourselves.”

There was a time, said Du Toit, when there were international involvement and interest in South Africa. “The one thing I have noticed is that the interest in SA is decreasing. Economic success did not come from ‘rooms of economists giving advice to presi-dents’, but from the bottom up, which is what PALS were about. Social development and not politics should be our obsession,” said Du Toit.

Agriculture needs to change the narrative, as the land debate is only driven by fear, says Pieter Prinsloo, committee member from the Eastern Cape PALS initiative. “Expropriation without compensation, land reform, and safety and security are worldwide problems that are not unique to SA. We are scared of what is going to happen, instead of being straight and honest about fear and addressing the fear. Come to the table and talk about what we fear. I don’t think the changing of the Constitution was ever intended to dispossess people who are producing off the land.

Nicholas Dicey (Hortgro Chairman), Pieter-Steph du Toit

(World Ruby Player of the Year) and Anton Smuts (VinPro

Chairman) at the Landbouweekblad-PALS symposium

Ivan Ka-Mbonane (legal advisor to Minister Didiza),

Nicholas Dicey (Hortgro Chairman), and Minister of

Agriculture, Thoko Didiza

“The message was clear: we cannot let agriculture

fail. SA’s agricultural sector is pivotal in

ensuring food security.”


"We have identified common ground. We must talk as a collective. My message is, change the narrative,” said Prinsloo.

ZZ2 Managing Director Tommie van Zyl, asserted that transparency is the name of the game. “The future is much more important than the past. We need to create a farmers’ brand that every South African can be proud of. To do that, we have to embrace diversity. There is no one-size-fits-all solution. Something may succeed in one situa-tion and for one project, but in another situation, it will fail. We have to be open-hearted and open-minded.” “Several speakers fingered

corruption as an obstacle in land reform and transformation.”

Sibongiseni Silwana joined the FFC team in early 2019 as Soil Scientist and Citrus Consultant. He is passionate about regenera-tive agriculture and has experience with cover crop selection and soil health improvement. Sibongiseni holds a Msc. Agric degree from Stellenbosch University.

Roelf Meyer from the In Transformation Initiative said that land reform should not feel like an ob-ligation. “South Africans should have a change of heart, to share our country, to implement new ways to ensure the future of our agri-business-es.” According to Meyer, farmers are now in a better position than ever before to have access to the government. This statement was validat-ed by the presence of several provincial and government officials. Meyer also indicated that the economy was moving in the right direction.

“We won’t see changes tomorrow, maybe in three to five years’ time.”Gielie Geldenhuys and Tommy Mona, partners in Bambisane Farming said all South Africans – not just commercial farmers – have a moral obligation to make land reform work. “On our farming en-tity, the next generation is already involved. That makes us excited and motivates us to succeed at all costs. Failure is not an option,” said Gelden-huys. Mona called on the government to make transformation initiatives easier for farmers. There is a lot of red tape and ignorance in government departments that do not communicate with one another. This causes frustration in an already difficult process, he said.

Minister Didiza got a chance to react to some of the critics when she concluded the proceedings. “I listened to all your stories and saw today that there is a new way of doing things that can bring all South Africans together.” Turning to Bon-nievale farmer Phillip Jonker, who told the story of how the community came together, concep-tualised and built the Jakes Gerwel Technical School in Bonnievale, she said, “Phillip, you made me cry today. What an extraordinary ex-ample you are for us all.” Didiza told the farmers that despite difficult circumstances, they “have all proved the willingness to make things work”. “We will work with you. Tough times don’t last, tough people, do.” ✤

JD Botma has recently joined Firstfruits Con-sulting as Soil Scientist and Citrus Consultant.

JD obtained his BSc Agric degree from Stellenbosch University in 2018, majoring in Soil Science and Horticulture. JD has gained intensive experience in soil classification, having classified soil in every province in South Africa and abroad since graduation.

Dirk Klaase joined our Precision Farming team in 2019 as Precision Services Technician. Dirk was previously a citrus farm manager and has gained valuable experience in citrus production practices. Dirk excels in leadership roles and will be managing the execution of infield precision services.

Nyasha Manhuru has joined the Precision Farm-ing team as assistant technician. He has an eye

for detail and assists with the training of farm pest scouts for crop protection purposes for citrus growers. Nyasha is an experienced pruner and assists with training and supervision of pruning teams after pruning demonstrations by Firstfruits’ Citriculturists.

We would like to welcome the following members to our team

[email protected] | www.1stfruits.co.za | 021 001 3134

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I don’t think I’ve ever seen Saul not knowing what to do. He works independently and is very knowledgeable, headstrong and pas-sionate,” says Danie Viljoen, Farm Manager

of Lushof about Saul Lintnaar, one of his pro-duction managers. “His go-getter attitude has caused friction in the past and sometimes still does, but all in all, his energy and savvy have earned my trust over the years. My weakness is that I procrastinate; he doesn’t …”

Saul was born in the Warm Bokkeveld on the farm Agterfontein, where he grew up and went to school. During all of Saul’s schooling years, farming was never a career option. He was going to study Law, but after matric he threw a curveball by joining the army for three years, ending up on the border at Oshakati in the then South-West Africa. After Namibia’s independ-ence in 1990, the SADF withdrew from there and Saul ended up working as a security guard in Cape Town for one year. By that stage, he had still not considered farming. But when his mother ended up alone on the farm Loxtonia, he returned to take care of her. Saul started working, but not whole-heartedly.

“One day, when we started planting potatoes, something happened. You know, when you plough the land, you get that warm smell of the soil. A very specific, wonderful smell. Suddenly I realised this is something I’ve missed for a long time. The emotion was so strong that I had to ask my mother why that was.

“She just smiled with a knowing look in her eyes, explaining that when I was born 22 years before, she was a worker on Agterfontein and could not afford not to work. Those years there wasn’t maternity leave for farmworkers, so she took me with her and put me under a tree next to the potato field. Every time, after planting a

row, she returned to breastfeed me. My nose would be full of that freshly ploughed soil!” The association with the smell and the security of a mother being there feeding him were the spark that brought Saul’s heart back to the farm. It was his homecoming.

He started working as an ordinary farm work-er for a weekly wage of R60, and had a lot of objections from the rest of the community, because he had passed his matric, completed three years of army duty and worked in Cape Town. Yet there he was, working with un-schooled labourers.

“But I had my reasons. I had to earn my keep, I couldn’t jump in ahead of anyone. That would have been unfair. I progressed to irrigation and then discovered I was a good pest scout. During the first scouting competition, I came second. In the two subsequent years, I was the cham-pion pest scouter on the farm. After earning colleagues’ respect, I responded to a recruit-ment advertisement and joined Lushof as a total outsider. I guess I love challenges.”

Saul is headstrong, but he is fair and works extremely hard. But above all, Saul is filled with gratitude. At first, he did not understand where it came from, but as he progressed through the ranks it became evident that he has always fended for the underdog; devising plans to help those who are not rooted in anything they can believe in.

It’s all about the bees and the ballsAs part of his job he had to move beehives into certain orchards, where they performed as pollina-tors. “That’s where this bee bug bit me, but I’ve also been stung a few times! Bees are big busi-ness for prune, apple and pear farmers. No bees, no crop. So I asked Danie if I could get involved in

Saul Lintnaar from the Graaff Fruit Farm Lushof, was a finalist at the Deciduous Fruit Industry Gala Awards 2019 in the category Advanced Agricultural Worker. Although he didn’t win this one, Saul has many awards under his belt. However, awards are not what makes him a winner. For him it’s all about mastering the art of paying it forward.

A whole lot of Saul


supplying bees for pollination and he said yes. It’s only my brother, a friend and me managing it in my own section on the farm. We started small and financed ourselves. Every year, I’d take my bonus and buy a few hives. Today we have 40 and need a lot of hands to move them from orchard to orchard during pollination season.”

That’s when he started involving unemployed kids from the community to help him. They’re getting good at it and it is good to be able to help them earn some money, he reckons. They’re keen and it keeps them off the streets and away from getting involved in the bad stuff.

Rugby is another example of Saul’s unique brand of involvement with the youth. His love for the game started early, as his much older brother, Sors, played the game. Every boy must have a hero. Therefore, Saul attended almost every game that his ouboet played. The arrival of the television broadened his rugby horizons to include Boland, Western Province and his ultimate heroes, the Springboks.

“I cannot understand how any born and bred South African can support the All Blacks. It doesn’t make sense. But the Young Black Ar-rows, a local farm team, is a different story. After I stopped playing myself, I became their team manager.” Managing the team was ok, but Saul was eager to coach, so, he empowered himself. Saul completed Coaching Level One and Two courses at Boland Rugby Union in Wellington. That’s when he formed The Young Eagles, Lushof’s own team. In their first two years, they ended up champions of the local league. The bigger clubs then started to take notice of the quality of players Saul turned out and would make them better offers.

“It’s ok, as long as I can help develop more kids, I’m happy, they can move on. It so amazing to

see these youngsters joining in, falling in love with the game, doing something healthy and positive with their lives. Becoming competitive for the right reasons.”

Some of his players played for Hamlet, winning the Witz Central league. The Boland Rugby Union is well aware of all these local leagues, constantly scouting for new talent. Who knows, Saul might have laid the foundation for a future Springbok or two, but the real reward for him is getting young-sters involved in something positive.

Saul’s focus is always on helping others. Often, people’s drive to help others springs from expe-riencing suffering yourself. This, however, is not the case with Saul. Although his father died when he was only two and his mother never remarried, he grew up feeling secure, never wanting for anything. The reason for that is his brother Sors – his ouboet –, who is 12 years older than Saul. Sors sacrificed his own future by leaving school to provide for the family (this he did well).

Saul now passes on the goodwill that his brother has initiated, to help other people live a bit better and have a bit more.

“Life is in a way like rugby, isn’t it? Making the right passes, passing on the good energy.” ✤

GERRIT RAUTENBACH

Saul, the honey bee farmer


It was a R2.5 million investment made by Hortgro Pome last year that spawned this industry gem. Post-harvest research is critical to the future success of new apple cultivars. Therefore, the goal with this facility is to help solve post-harvest challeng-

es within the deciduous fruit industry.

On 5 November 2019, approximately 80 people attended the CA storage research feedback held by the Hortgro Science CA Storage Group at the Department of Horticultural Sciences. This meeting is held annually in November, with a record attendance last year.

Since the industry has identified CA storage as a gap in research, it has stimulated funding, research and collaboration between all research organisations on this topic, bringing new ideas to the party and giving this research theme momentum. This also pro-vides the industry with much needed post-graduate specialists in this field. Two students, Monja Gerber (PhD) and Braam Mouton (MSc) presented their research projects on long-term storage techniques for Granny Smith apples. They worked under the supervision of Dr Elke Crouch and collaborated with Dr Pandian Thirupathi (post-doctoral fellow).

CA facility turns oneELKE CROUCH

From left to right: Prof. Wiehann Steyn (Hortgro), Dr Pandian Thirupathi (SU), Mr Gustav Lötze (SU),

Ms. Monja Gerber (SU), Braam Mouton, Ms. Anel Botes (ARC), Ms. Heleen Tayler (Experico), Dr Elke Crouch (SU),

Mr Richard Hurndall (Hortgro, CA group Chairman)

The state-of-the-art controlled atmosphere (CA) facility at Stellenbosch University’s Horticultural Sciences Department celebrated its first birthday this year.


Monja Gerber’s project is also funded by the Post-Harvest Innovation Fund, underscoring the importance of this type of research. This study is done in collaboration with the ARC (Anél Botes) and Experico (Daniël Viljoen). Braam Mouton’s study looks at differences in quality after storing fruit for nine months under low oxygen storage techniques that adjust the atmosphere ac-cording to the fruit condition. Other topics covered were Cripps’ Pink browning factors during long term CA storage presented by Heleen Bergman (Experico). This was done in collaboration with Dr Elke Crouch and an honours student, Tsepo Kholoane from SU. Long-term storage techniques of pears were covered by Anél Botes from the ARC.

An international guest from Bolzano, Italy, Hubert Wieser also presented new Isolcel CA technologies that allow for more accurate measurements of DCA-RQ (Storefresh); new intelli-gent CO2 scrubbing systems that reduce the use of electricity consumption by 50% (ECO line); and digital starch breakdown measurement (Amilon). Vega Brink from Gas at Site gave an

update on dynamic controlled atmosphere adoption in the USA.

The day proved that the foresight of Richard Hurndall (CA group chairman at Hortgro) in driving the revival of the CA was well timed. Hurndall quoted the first CA group chairman John Findlay, who liked to say: “We are here to learn from our mistakes.”

Space is currently a challenge for CA research. The equipment installed at the Department of Horticultural Sciences has the capacity to run larger units but currently, there is no more available space to add to the current airtight containers for vital long-term storage trials. This requirement is due to the fact that higher prices are earned by supplying fruit in the offseason. However, storing at a high cost also presents significant risks, which can be mitigated through research. Prof Wiehann Steyn from Hortgro has taken over the reins from Richard Hurndall and will be driving the CA research theme, as well as funding to further address these future challenges. ✤


SA’s growth rate could pick up faster than expected if the correct structural reforms are in place,” Botha said.

“Economic recovery beckons if the National Development Plan is implemented,” he continued.Botha, the economic advisor to the Optimum Financial Services Group, delivered an address at the recent annual congress of the International Prune Association (IPA). The IPA was estab-lished in 1990 and is the prune industry’s trade entity, representing the interests of prune growers and packers across the globe. The event, held in Cape Town from 28-29 October 2019, was attended by approxi-mately 50 participants from the USA, France, Argentina, Italy, Australia, Chile, and SA.Botha shared an overview of SA’s economic and market potential, given current policy directions.

Agriculture is a “vital sector”The estimated output of the agricultural sector in SA was R100 million in 2017. “It doesn’t seem much. But if you put the value of agriculture through the whole supply chain, the total linked turnover was R1,97 trillion,” Botha explained. SA’s primary agricultural trade balance has indeed grown significantly in recent years. As Botha also pointed out, the country had a R126 billion surplus since 2013.

From January to June this year, SA exported approximate-ly 20,7% of its agricultural goods (valued at R65,6 billion) to Europe. SA is also a key food exporter to countries in Southern Africa. “Agriculture is the most diversified sector in our econo-my,” Botha said. “It remains a vital sector to enable economic growth and job creation. The African continent has 170 million more people than a decade ago. And Africans are starting to eat

more fruit and more protein,” he highlights. “This opens up new opportunities for inves-tors in the value chain.”Angola is one of the countries holding huge investment potential linked to the agricultural sector, says Botha. Mauritius, Botswana, SA, Namibia and Angola are at the top of the list of countries in the region, with relatively high GDP per capita growth rates.

Dealing with land reformBotha identified the land issue as a key factor for investment and growth in the country. “The big issue is land expropriation with-out compensation or comprehension. It is a shortcut to poverty,” he said. “If we do the land reform thing in SA, we need to do it smartly. The good news is that we won’t fall off a cliff. We have the most differential economy in the world.”There are many examples around the world that underscore the

Economist Dr Roelof Botha is optimistic about investment and agricultural prospects in SA.

JORISNA BONTHUYSJORISNA BONTHUYS

SA’s prune industry relishessigns of economic growth

“Agriculture is the most diversified sector in our economy. It remains a vital sector to enable

economic growth and job creation.”


importance of policy to a country’s economic prospects, especially when it comes to land reform. “Policy ruined countries like Venezuela and Zimbabwe, turning them into failed states in no time,” Botha explains. “Luckily, the policies of President (Cyril) Ramaphosa and his predecessor Jacob Zuma differ like night and day.”Botha said there are certain enabling factors needed to develop food and agriculture value chains. He divides these factors into three categories: “essential”, “important” and “use-ful”. The “essential” enabling factors include property rights, adequate infrastructure and supportive trade policy that does not compro-mise productive land for agriculture. “Impor-tant” enabling factors are standards and reg-ulations, sufficient research and development, and access to financial services. The “useful” factors consist of, among others, ease of doing business and business development services.

“Green shoots are appearing”SA has had serious structural constraints to growth in recent years.

Opposite: Ceres Grower Raymond Koopstad

(pictured here with Maggie Jantjies) from

La Vouere, is an example of “agriculture

creating economic growth and jobs”.

Koopstad recently planted an additional

17.8 hectares of nectarine varieties.

T he International Prune Association (IPA) recently planted a young prune tree on the grounds of a farm school, Botha’s Halte Primary School, in the Breede River Valley. It’s a couple of kilometres from where the most

successful SA prune variety was first discovered in the 1960s.

The tree, a Van der Merwe prune variety, is considered to be one of the best prune varieties in the world. The IPA recently visited the region and was so im-pressed with the state-of-the-art farm school on Bosjes Farm that they decided to donate a tree to the school. The prune variety was discovered on a neighbouring farm that belonged to Koos van der Merwe.

The Van der Merwe requires less winter cold to bear a good crop and is better adapted to the main production areas of SA: fairly mild winters with plenty of sunshine. The first prune trees in SA, Prune D’Agen, were imported by Harry Pickstone in 1892. The Van der Merwe variety is a genetic mutation from the original French variety.

The IPA Chairman Chris Krone, said that the IPA hopes that the children will enjoy the fruit and the shade of the tree. “We want you to know where your food comes from, and hopefully some of you will one day make agriculture your career.”

The revamp of the Botha’s Halte Primary School was initiated by the Bosjes Trust, with the aim of creating a centre of learning excellence for the benefit of farm-workers’ children and the greater community. The “green” school boasts its own greywater system, solar and wind energy, as well as water supply.

#education #empoweringouryouth

Above: Planting a Van der Merwe for the future! With the children are

Leonard Stemmet (Bosjes Trust), Chris Krone (IPA Chairman) and

Nicholaas Pedro (Botha’s Halte Primary School principal)

Prune tree – symbol of the futureELISE-MARIE STEENKAMP

CONTINUED ON PAGE 20


Can prunes reverse bone loss?

Osteoporosis is a condition that refers to the weakening of bones outside of a normal range, to a point at which people’s risk of sustaining a bone fracture increases,

particularly in the spine, hip and wrist. Donn Zea, the executive director of the California Prune Board, presented some results and preliminary findings of the latest cutting-edge research on this topic at the annual congress of the International Prune Association (IPA) held in Cape Town from 28-29 October 2019.

Due to its prevalence worldwide, osteoporo-sis is now considered a serious public health concern. As the world’s demographic shift to an older population continues, more people will be diagnosed with osteoporosis. It is estimated that more than 200 million people suffer from the disease across the globe.

A current study funded by the IPA and the Californian Prune Board is the largest clinical trial to date. The researchers are investigating the relationship between eating prunes and the maintenance of bone health

in postmenopausal women. This study builds on the results of pre-clinical and clinical trials over the past two decades. Final results aren’t expected until the end of 2021. But already there’s promise. Zea highlighted: “There are once again indications that prunes may help prevent bone loss and preserve bone structure in postmenopausal women. This can help to reduce the risk of fractures, related to osteoporosis, happening.”

In one case, a 55-year-old woman who completed the study as part of the control group (the group that did not eat prunes) had lost bone density as measured by three different scans at the beginning and end of the period. She decided to consume 50 g of prunes per day, of her own volition. Four months later, the scientists who monitored her progress reported a marked improvement in her bone mineral density. During this period,

her spine bone mineral density increased by 7,9%, returning to levels above when she had started to participate in the study.

A growing body of research suggests that eating prunes could improve bone health in postmenopausal women who have low bone mass. In some cases, it might even reverse

bone loss caused by osteoporosis.

Botha summarised it as follows: “The recession hit us, we expe-rienced the worse drought in known history and we lost almost a decade (because of policy instability) under Zuma’s rule. Those structural constraints are, however, now behind us.”

Botha said the tide is turning in the economy. “We are seeing green shoots appearing.” More tourists have, for instance, start-ed to visit the country again. SA’s imports and exports are also

increasing. “Things are happening in this economy,” he points out. “It is difficult not to be optimistic about SA at the moment.”

He projected that SA’s economic growth will increase to 2,2% next year, saying the “Ramaphosa effect” is already improving the country’s investment prospects. Botha concluded: “The ag-ricultural sector is a crucial job creator to ensure growth and job creation. We need to invest heavily in this sector.” ✤

CONTINUED FROM PAGE 19

“There are once again indications that prunes may help

prevent bone loss and preserve bone structure in

postmenopausal women.”


“These results were so promising that the primary investigator presented them to members of the American Society for Bone and Mineral Research in September,” says Zea. Prof Mary Jane De Souza from the Department of Kinesiology and Physiology at Penn State University in the USA is leading this research project. The results suggest that a non-pharmacological (dietary) inter-vention of 50 g of prunes daily, in addition to daily supplemen-tation of calcium and vitamin D, may have a greater impact on bone mineral density than calcium and Vitamin D supplemen-tation alone in postmenopausal women with osteopenia. This condition is often a precursor of osteoporosis.

The research shows that eating prunes improves the effect of osteoblasts (the bone-building cells) and reduces the effect of osteoclasts (the cells responsible for its resorption), Zea ex-plained. Osteoblasts are needed for bone synthesis and minerali-sation, both during the initial formation of bone and during bone remodelling. Bone is a dynamic type of tissue that keeps chang-ing throughout your life — new bone is made and old bone is broken down. In postmenopausal women, the declining rates of the hormone oestrogen can increase the rate of bone resorption (when bone is broken down). The older you get, the greater your risk of developing osteoporosis.

According to Zea, exactly how prunes are improving bone health remains a mystery. “While we don’t understand the exact mecha-nism in which this occurs, it’s very likely a synergistic effect of source nutrients alongside some powerful polyphenols (plant compounds packed with antioxidants).”

Besides this study, more work is underway to explore the links between eating prunes and bone health in men as well as

younger women using steroidal contraceptives, where a loss in bone mineral density has been associated. Research is also underway to investigate the effects of eating prunes on the bone density of people with spinal injuries and those who have suffered wrist fractures. According to scientists, women are much more likely to develop osteoporosis than men. The reduction of oestrogen levels in women during menopause is considered one of the strongest risk factors for developing this condition.

Dappie Smit, Hortgro’s general manager responsible for dried fruit, says efforts are underway to understand the benefits of prunes on bone health and to address lifestyle diseases. “The people living in Agen, in southwest France, eat plenty of foie gras, drink lots of red wine, eat prunes and enjoy low levels of heart disease. This is called the ‘French paradox’ and has led to research projects on the effects of prunes on heart disease, digestive disorders, weight control and efforts to promote bone density.”

In recent years, the use of non-pharmacological interventions to reverse low bone density has gained lots of traction. These and other research efforts help ensure that producers remain competitive, Smit indicated. The bone density research is already in the clinical phase, meaning it is being tested on groups of people while their bone density and other markers are being monitored. “Seeing that most cancer treatments also affect bone density, the research could also make a positive contribution in this regard,” Smit said. “The study also helps unlock a new understanding of the health benefits of prunes and ways to com-municate about it to younger and health-conscious consumers,” he indicated. ✤

Attending the IPA Congress in Cape Town – Pedro-Pablo Diaz (Chile), Chris Krone (IPA Chairman),

Dappie Smit (Hortgro) and Donn Zea (USA)


The Hortgro Science stone fruit field day took place at the end of last year with more than 80 growers attending this popular event at Oudewagendrift, Worcester. The field days are primarily focussed on production and how growers can produce the highest quality crop. Attending growers had the opportunity to view orchards, and specialists who accompanied the tours, discussed pre- and postharvest challenges. This allowed for insightful debates between growers and researchers.

Hortgro would like to thank Wilhelm Naudé and Charl Stander for their support.

Left: Growers enjoy a chatty ride to the orchards

Top: Growers get the lowdown on the impact of

netting

Above: Charl Stander and Gielie Bester highlight-

ing the precision needed in the thinning process

CARMÉ NAUDÉ

STONE FRUIT

field day


The deciduous fruit industry had an excellent crop of winners in 2019, with several of our industry representatives winning top awards.

DECIDUOUS FRUIT WINNERS 2019

Hugh Campbell (in blue cap), Hortgro Science manager, starting the formalities

of the day

Wilhelm Naudé explaining the thinning process

of late plum variety, Angeleno

Above left: Buks Nel was named Agriculturist of the Year. Middle: Sewis van der Horst was crowned the Toyota Young Harvester 2019,

following in the footsteps of Jacky Goliath, Trevor Abrahams, Ricard Myburgh and André Cloete. Right: Ricard Myburgh clinched the

Jobs Fund Young Entrepreneur Award for 2019.


Werkers van die Bergrivier-tafeldruiwe-streek (BTPV) het drie van die kate-gorieë by die 2019 Landbouwerker

van die Jaar op ’n groot hoogtepunt op Sater-dag 2 November 2019 in Nederburg afgesluit. Daar is behoorlik uitgehang vir die 700 gaste, en die aand was blink en mooi met Vinette Ebrahim (Charmaine van 7de laan) as seremoniemeester. Heerlike kos en vermaak, asook insiggewende toesprake het gesorg dat dit ’n besonderse aand was. Die Wes-Kaapse Departement van Landbou, onder leiding van Joyene Isaacs en haar Landbouwerkers se Ondersteuning- en Ontwikkelingsdepartment, met Gertrude Jacobs aan die stuur tesame met ruim en jarelange borgskap vanaf Shoprite, verdien lof vir die genotvolle aand.

En natuurlik ook die paar trekkerdrywers wat saam met die vermaaklikheidskunstenaar Alistair Isobel op die verhoog gedans het. Dr Ivan Meyer, Wes-Kaapse Minister van Landbou, het in ’n roerende toespraak be-lowe dat veiligheid op plase asook die erge droogtegeteisterde gebiede sy onmiddellike aandag geniet. In elkeen van die 17 streke is daar uitdunne gehou en die eersteplek-wenners, sowel as die streekwenners het in 11 kategorieë teen mekaar meegeding. Die streke was Breede-riviervallei, Durbanville, Swartland, Overberg, Stellenbosch, Franschhoek, Tuinroete, Witzen-berg, Klein-Karoo, Langeberg, Sentraal-Karoo, Hexriviervallei, Bergrivier, Olifantsrivier, EGVV (Villiersdorp-omgewing) en Piket-Bo-Berg.

BERGRIVIER-WERKERS Blink uitEurica Scholtz, voorsitter van die Bergrivier tafeldruif streek is baie trots op hul landbouwerkers wat drie wenners by die 2019 Wes-Kaapse Prestige Landboutoekennings opgelewer het.

BAIE GELUK AAN HIERDIE DRIE BERGRIVIER-STREEKDEELNEMERS WAT IN HUL KATEGORIE TEEN DIE 16 ANDER STREKE GEWEN HET:

Middelbestuur Jerid-Lee Warries CemadarVoorvrou/man Audrey September UitkykTegniese spesialis (boordmoniteerder) Althrine Meyer Ferland

EN HIERDIE BERGRIVIER-WENNERS HET AAN DIE FINAAL DEELGENEEM:

Algemene Werker Christolene Lewis NancyAdministratief Racheline Mc Carthey LelienfonteinSosiale ontwikkeling Janine Baron Die KruisBesproeiingspesialis Dawid du Toit WynkeldershoekTegniese spesialis Althrine Meyer FerlandTrekkerdrywer Nicadow Saroon CemadarVoorvrou/man Audrey September UitkykJunior bestuur Tumiza Nkanunu SteenebrugMiddelbestuur Jerid-Lee Warries CemadarBeste potensiaal Usokarl Lof Môrester BoerderyBergrivier-streekwenner Jerid-Lee Warries Cemadar


BTPV, die eenheidsbestuurders en die ander landbouwerkers in die streek is trots op hierdie span. In hierdie gesogte kompetisie met meer as 1 000 inskrywings, het hulle die Bergrivier-streek met soveel waardigheid verteenwoordig.

’n Baie groot dankie aan Liezl Jonker, bestuurder van die Bergrivierstreek, wat jaarliks die kompetisies in hul streek reël. Die reëlings was puik!

En aan al ons sterre, sterkte met die pad vorentoe en hou aan blink.

Minister Dr Ivan Meyer, Wes-Kaapse Minister

van Landbou, Middelbestuurwenner Jerid-Lee

Warries, Cemadar, Broodkraal Landgoed en

Isaac Ntoto, wenner: 2018 Wes-Kaapse Prestige

Landboutoekennings.


The South African Table Grape Industry (SATI) released the second crop estimate for the 2019/2020 season with a lower estimate of between 59,55 million and 66,3 million cartons (4,5 kg equivalents), exclusively caused by significantly lower volumes from the Northern Provinces region.

Second crop estimate:2019/2020 season

SOUTH AFRICAN TABLE GRAPE INDUSTRY

2nd Crop Estimate for 2019/2020 season (4.5 kg equivalent cartons)

L-R: SATI CEO Willem Bestbier, Western Cape

Minister of Economic Opportunities David Maynier,

and Head of the Department of Economic

Development Solly Fourie. They received grapes

from Willem, from the 2019/2020 season.

The estimate for all other regions remains unchanged.The Northern Provinces, Orange River Valley and Olifants River Valley started their respective seasons on time, but the Berg River and Hex River Valleys seem to be at least 1 week earlier than usual. Throughout the regions berry size is good and to date night temperatures have been lower than normal, which is conducive to good colour development of red and black varieties.

With water resources well replenished it seems that the Olifants River Valley has finally recovered from an extended drought. The industry as a whole will, however continue to manage water most responsibly.

According to Willem Bestbier, CEO of SATI, the 2nd crop estimate reflects a normal crop. He reiterated a strong focus is on quality and service.

This summer rainfall region was hit with unusual continuous rains during its peak harvesting period, and a crop volume reduction of 1,5 million cartons is estimated for the region (see below).

(18 December 2019) (18 October 2019) REGION LOW HIGH LOW HIGH 2018/2019 2017/2018 2016/2017

Northern Provinces 5,65 6,30 7,15 7,80 7,121 6,829 5,538

Orange River 18,50 19,90 18,50 19,90 19,207 19,016 20,533

Olifants River 2,10 2,50 2,10 2,50 2,367 2,802 3,968

Berg River 13,50 15,30 13,50 15,30 13,789 13,053 15,426

Hex River 19,80 22,30 19,80 22,30 18,649 20,365 22,111

Total 59,55 66,30 61,05 67,80 61,133 62,065 67,575

ACTUAL PACKED VOLUMES2nd ESTIMATE 1st ESTIMATE

28 PROMOSIE | FEB/MAART 2020

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Fumigation is an effective method for treating diseased soils, but requires specialised skills and application methods in order to deliver the desired outcome. Establishment of a new crop is a large investment and for that reason, disinfection should be thorough.Previously, soil was fumigated with methyl bromide, which delivered excellent results. However, methyl bromide had to be phased out in terms of the Montreal Protocol, because of its detrimental effect on the ozone layer.

This led to the search for appropriate alternatives. International research eventually proved that fumi-gants containing a combination of 1,3 dichloropro-pene and chloropicrin are the best alternative to methyl bromide in terms of efficacy, but it doesn’t have the same potential in terms of distribution through the soil from point of application. Fortunately, NexusAG and AQL developed an integrated service model to address this challenge. Agrocelone NE, distributed by NexusAG, contains the optimal combination of 1,3 D and chloropicrin and NexusAG invested in skilled personnel and advanced application equipment, in

order to ensure proper distribution through the soil. NexusAG uses unique application equipment with three shanks that enables wider diffusion and in so doing, delivering homogenous penetration of the soil for optimum results. Producers are also guaranteed accurate application due to GPS-driven tractors and AQL-automatic dosing system (DAS) technology, ensuring that the required dosage of the product is applied precisely where the crops will be planted.

This technology makes use of a closed system which combines GPS, tractor speed and electronically regulated application equipment. It improves the distribution of the product and work safety and guarantees dosing accuracy.

Soil fumigation is only intended for the control of damaging micro-organisms that are present in the soil. Fumigation may in some cases have a negative impact on populations of beneficial micro-organisms. Therefore, it becomes necessary, as per specific needs, to supplement these beneficial organism populations or to stimulate their establishment in the fumigated soil. Soil disinfection, therefore, begins weeks before treatment with identifying specific problems in the soil, and comprehensive planning in collaboration with the producer to define the specific requirements. An appropriate treatment program and different integrated options for follow-up treatment are created.

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Fig. 1. Free-hand (left) and GPS technology (right) that ensure the treated

strip runs exactly where the crops must be planted. This ensures that the

entire bank is treated effectively, with improved homogeneity.

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VEGETABLES

FRUIT &NUTSGRAPES

BERRIES


Eric is a committed farmer who has made a considerable contribution to the citrus industry, as well as to local organ-ised agriculture. He has been farming on Konzi Farm, north

of Fort Beaufort, since 1993. Eric serves on the Citrus Growers Association (CGA) Board of Directors, representing previously disadvantaged growers in the South. He is also a member of the Citrus Growers Development Chamber, and represents his region’s navel growers in the CGA Navel Focus Group. At a local level Eric is also Chairman of the Alice Kat Farmers’ Trust.

After completing a Diploma in Farm Business Management at Fort Cox Agricultural College, Eric applied for a farm under the Ciskei government agricultural land privatisation programme in 1989, and was delighted when this was successful. However, some tough years followed when in 1997 the Ciskei Agricul-tural Corporation and other parastatal organisations were shut down without any structures in place to continue the financial arrangements.

Fortunately, Capespan purchased the fruit from Konzi Farm and provided Eric with production loans. “Without this assistance at that time, we would not have been able to continue farming.” After many years of struggling, Eric has been receiving some government assistance in recent years. “I have managed to keep going through all these challenges,” says Eric. “My fruit is packed by Eden Agri Services pack-house, which is close to us and I am very hap-py with my relationship with them. SAFPRO is the company that exports my fruit.”

Eric and his wife Josephine have four children. “My wife and children love to be involved with the farm and I must thank them for their help and understanding,” says Eric. Their eldest son Sinovuyo Nohamba is 27 years old and has taken control of daily activities at Konzi Farm since 2014.

Sinovuyo explains: “I grew up in Alice in Amavuso Township with my parents, and attended high school in Alice. Subsequently, I attended the University of Fort Hare from 2009 to 2012. I did a

B.Ed. degree in Human Resource Management.” For his studies at Fort Hare, he received a Citrus Academy bursary. He also completed the highly successful Citrus Academy Citrus Business Management course in 2014 offered at the Mpofu Training Centre, and more recently he also completed the Citrus Academy short course in enterprise management in Pretoria.

“I was keen to start farming and chose to assist my father with our family farming operation, so I joined the farm in 2014. As the family home is in Alice, 50 km away, I moved to the farm to keep an eye on activities and progress. Initially it was very chal-lenging for me to live there but as time went by I became used to living the quiet, rural lifestyle. I enjoy what I do and consider

myself very lucky to be part of the family business,” says Sinovuyo.

“I am really grateful that Sinovuyo has chosen to get involved in our family farm. He is really doing well and having someone living permanently on the farm to keep an eye on things has made a big difference to production. The opportunities to learn about

citrus production through the Citrus Academy have been really beneficial for him, and I have peace of mind knowing that he is taking care of things on the farm,” says Eric.

“Our twins (a boy and a girl) are in their early 20s and they are both studying at the University of Fort Hare. Our son has com-pleted a Bachelor of Agriculture degree, majoring in Economics, as well as completing his honours degree in Economics and is currently studying to complete his Master’s degree. Our daugh-ter is in her third year of a B. Agric. degree.”

The Nohambas’ youngest son Sanele Nohamba is a serious

Eric NohambaLOUISE BRODIE

“My wife and children love to be involved with

the farm and I must thank them for their help

and understanding,”

SUCCESSION

Eric Nohamba above and

Sinovuyo Nohamba left


The Foundation was formed to promote the development of historically disadvantaged farmers and small suppliers of inputs in the CCBSA value chain, through the funding

of sustainable businesses. The training programme is designed to empower growers with the requisite skills to run their enter-prises efficiently. It covers a wide range of aspects, from produc-tion systems, handling and control of stock, human resources, basic finances and marketing.

The target group for the programme was new entrants into the industry, including young peo-ple from enterprises that are already operational to participate, as well as growers who had been identified as requiring skills in this area. Lack of business management skills has been identified as one of the leading limiting factors among most black citrus growers, hence the need to broaden access to this course. In an ideal world, growers are supposed to enrol in a programme of this nature as soon as they acquire their farms. However, in practice this is not possible, due to the lengthy pro-cesses of the land transfer system.

The plan was to train two people per farm across 50 farms. This would then encourage these enterprises to include young people for the purposes of succession which is at the heart of the industry and earlier this year the industry released a publication

entitled Stories of succession in the citrus industry. Further-more, empowering the youth is seen as a vehicle to ensure that new technologies are adopted at farm level. Scholastic articles indicate that older people are less likely to adopt new sustain-able practices and often rely on their indigenous knowledge to manage their farms.

The training was rolled out across five provinces and 91 people from 57 farming enterprises from Limpopo (34), Eastern

Cape (26), KwaZulu Natal (13), North West (10) and Mpumalanga (10). The group comprised 60 men, 31 women and 33 youth. The number of youth involved in the citrus industry is quite encouraging, which can also be attributed to the capacity development programmes that are run by the Citrus Academy. The increase in women’s

participation indicates a shift in cultural ideologies whereby women cannot own land or be involved in decision making on farms. The heterogeneous nature of the group brought a lot of benefit during the training, as it allowed for mutual knowledge transfer. The attendance of a representative from the CCBSA at some of the venues was also encouraging, since the farmers were inquisitive about the work of the Foundation.

As the CGA GDC, we look forward to more partnerships of this nature unlocking the potential of the industry and the sector at large. ✤

Economic growthTRANSFORMATION

Effective transformation requires partnerships with like-minded private sector stakeholders. The CGA Grower Development Company (GDC) has partnered with Coca Cola Beverages SA (CCBSA) Mintirho Foundation to fund training targeted at 100 black citrus growers who will attend an “Introduction to Citrus Business Management” course.

Effective transformation requires partnerships

with like-minded private sector stakeholders.

sportsman. Although now in his second year at University studying for his B. Comm. degree, he currently plays rugby for the Sharks under 19’s as well as the Curry Cup squad. “Our children make us proud,” says Eric. ”Our farm has created a platform from which they can become involved in agriculture on several levels, however one must be passionate and dedicat-ed in order to be successful at farming, as it is not easy.

“Looking into the future I would encourage them to look at ag-riculture as a sector with opportunities for them to develop their careers. It is my dream to expand my farming operation, so there are more farming opportunities for them in the future. If they are not interested in the production part of agriculture, the export supply chain also offers many good career options that they could consider.” ✤

YOLANDA NTLAKAZAManager: Business Support


The Citrus Academy's short courses are aimed at provid-ing insight into the essential components of the citrus production system. They give a good induction into the subject matter, and help with understanding how these

components fit into the broader system. The courses are also a good starting point and guide in terms of choosing a suited career in the citrus production system.

The three main components of the system are covered through short courses in Citrus Production, Citrus Packing and the Citrus Export Supply Chain. These are supported by the widely applica-ble Citrus Business Administration short course.

Citrus productionSince the rollout of the Citrus Production short course in Fort Beaufort in October 2018, over 340 learners have been enrolled to attend the course across various citrus growing regions coun-trywide. Learners have mentioned, in particular, how they bene-fitted from the site visit held on the third day of the course, as it gave them insight and practical application in terms of what they had learnt over the first two days spent in the classroom. While

this particular short course focusses on various aspects of citrus production, it is aimed at those who are looking to obtain a high level of understanding of all aspects of citrus production within a short period of time. The feedback from learners has been very positive to date, with most commenting on the knowledge attained and skills acquired, which they feel will translate into practical knowledge about the day-to-day production practices on their farms.

The Citrus Academy secured funding that allowed for the spon-sorship of approximately 60 learners from developing farms to attend this course. These learners, in turn, expressed their sincere appreciation and gratitude for the opportunity to utilise their new-ly acquired skills in the ongoing development of their farms.

Citrus Business AdministrationCitrus Academy followed on the Citrus Production short course with the implementation of the Citrus Business Administration short course. This course was also held over various citrus growing regions across the country, and was deemed highly in-formative by all who attended. Facilitated by Scientific Roets, this

CITRUS ACADEMY - DRIVING SKILLS DEVELOPMENT

One short course at a timeSIVE SILO

Citrus Export Supply Chain learners from Somerset West, with Citrus Academy staff


Citrus Production short course learners in Stellenbosch, with facilitator Clive Pountney (centre), and

Citrus Academy staff member, Nonhle Mbhele, front row, far left

Citrus Business Administration learners in

Sunday’s River Valley, with facilitator,

Mpho Mazubane (centre), from Scientific

Roets

course is ideal for anyone involved in the citrus production system who is looking to improve their skills in financial accounting (including budgeting), stock management, human resource management, production management and marketing. The course is aimed at giving attendees a solid understanding of all of these aspects. Learners attested to benefiting from the well-organised course, and were particu-larly pleased with the course resource pack, specifically the course learner guide, which can be used as a future reference guide.


E-learning is here to stay. Internationally, there is an upward trend in the use of electronic technologies to supplement traditional teaching methods and to provide access to learning outside of the classroom. As computer ownership grows and internet connectivity speeds are becoming faster, e-learning is becoming increasingly viable and accessible. Due to its convenience and flexibility, the resources are available from anywhere and at any time. Everyone, whether part-time students or full-time employees, can take advantage of web-based learning.

The Citrus Academy is committed to both keeping up with the latest developments in skills delivery, as well as enabling the provision of training programmes to remote rural areas by supply-ing mobile learning resources. In keeping with these objectives, the Academy has been refining and expanding its e-learning platform. The aim is to provide an interactive multimedia learning experience to everyone in the industry.

Currently, learners who attend the Citrus Academy short courses, such as the Citrus Production and Citrus Export Excellence, are given access to the e-learning platform, which includes all the learning material as well as audio-visual clips and links to external resources. Learners also complete the competence assessment activities online.

The initial response has been so positive that the Academy intends to make more e-learning programmes available this year, starting with the Citrus Business Management Programme. This programme is based on the New Venture Creation NQF4 qualification (US66249) registered with Services SETA, and will be delivered as 10 modules over a period of 10 months.

Learners will study the modules and complete the portfolio of evidence entirely online. The Academy will provide user support and learners will be assessed by a qualified and ex-

perienced assessor. On successful comple-tion of the programme learners will be awarded the Further Education and Training Certificate: New Venture Creation (NQF4). ✤

CITRUS ACADEMY

Entrenching e-learningDESIREE SCHONKEN

Citrus Export Supply Chain Being the latest of the short courses to be implemented, this is an exciting course that offers an understanding of each aspect of the citrus value chain. Every person in the citrus production system should have an understanding of what happens to export fruit after it leaves their hands, and this short course is the ideal induction to the export supply chain.

Enthusiastic learners attending the course gained much in terms of learning about the export supply value chain, and especially from attending the site visit to the port. They were able to meet with terminal staff and even see the vessels – a rare opportunity. Thank you to Andy Connell, industry expert and facilitator of the short course, who provided valu-able insight into the entire value chain and its links.

Course dates:Date Course Location

22-24/01/2020 Citrus Export Supply Chain Coega

29-31/01/2020 Citrus Export Supply Chain Addo

29-31/01/2020 Citrus Production Pietermaritzburg

12-14/02/2020 Citrus Production Stellenbosch

20-21/02/2020 Citrus Export Supply Chain Limpopo

19-21/02/2020 Citrus Packing Fort Beaufort

26-28/02/2020 Citrus Production Hoedspruit

04-06/03/2020 Citrus Export Supply Chain Durban 1

Course information and registration: www.citrusacademy.org.za

Enquiries: Sive Silo at 031 765 3410 or [email protected]

For further information regarding costs and schedules of courses, please contact Desiree at [email protected]

or 031 765 3410.


The Citrus Growers Association holds its Citrus Sum-mit bi-annually, with the first one having been held in 2015. By 2017 the Summit had reached sufficient financial stability to be able to donate its profits to

local communities.

Charitable associations or ventures are requested to submit a list of their needs, up to the value of R50 000. The CGA then choses two that it feels are the most deserving of the donation, and after the Summit in March, the CGA director of the region where the charity is based visits the establish-ment and presents the cheque to the management or owner.

One of the two winning charities for 2019 was Quacha Klouter Kabouter, a pre-school for the children of employees at Quacha Farm in the Gamtoos Valley situated in Patensie, Eastern Cape.

This school opened in 2014 with 12 farm children, and has since grown to 30 children enrolled, with two trained teachers, one of whom used to be a general farm worker on the farm.

Quacha Klouter Kabouter is vibrant, multi-racial and multi-cultural, and the kids receive opportunities to develop aca-demically, socially, physically and emotionally.

Martina and Kobus Odendaal, the owners of the farm, along with their son and daughter Dirk and Marelise, welcomed CGA Director Phillip Dempsey when he arrived for a walkabout and to take some photos. He was shown what had been purchased with the Orange Heart donation: the new jungle gym, photo-copier, laptop computer, fridge and stove have made a huge difference to the comfort and pleasure of the children and their teachers.

CGA alms add zest to Klouter Kabouter GLORIA WEARE

GEBRUIK PLANTBESKERMINGSPRODUKTE MET VEILIGHEID EN VERANTWOORDELIKE SORG.VOLG AANWYSINGS OP ETIKET TEN ALLE TYE MET TOEDIENING VAN PLANTBESKERMINGSPRODUKTE.

TD 18/142R

Kry meer as net gewasbeskerming

Coragen® bevat chlorantraniliprool (antraniliese diamied) (Rynaxypyr®) Reg. Nr. L8529 Wet Nr. 36 van 1947, versigtig.FMC Chemicals (Edms) Bpk, Posbus 44, Postnet Menlyn, Waterkloof Glen, 0081, Republiek van Suid-Afrika. Tel: +27 12 003 2938.Coragen® en Rynaxypyr® is handelsmerke van FMC Korporasie of sy affiliate. Datum: 08/2018.

Coragen®

i n s e k b e h e e r

aangedryf deur

aktiewe bestanddeel

STAATMAKER VALSKODLINGMOTBEHEER WAT SO SLIM SOOS JY WERK. Vir die boer kom elke seisoen met ’n lys van uitdagings. Gewasbeskerming moet egter nie een van die bekommernisse wees nie. Dit is hoekom ons Coragen® insekbeheer ontwikkel het; een van die mees gevorderde produkte vir insekbeheer in die wêreld. Om slim te werk het nou baie makliker geword danksy die vinnige en lang nawerkende Valskodlingmotbeheer in sitrus. Coragen® insekbeheer bied ’n unieke metode van werking met ’n uitstekende toksikologiese- en omgewingsprofiel. Die nuwe wapen in die geïntegreerde beheer arsenaal teen Valskodlingmot en beter vrugkwaliteit verlaag die risiko van afkeurings vir uitvoervrugte na die meeste uitvoermarkte. Beter gewasbeskerming en bewaring van voordelige insekte – dit is mos wat elke sitrusboer wil hê.

Kontak jou naaste FMC-handelaar om meer uit te vind oor Coragen® insekbeheer.

From top to bottom: And what would a pre-school be

without a brand-new set of swings? | The children enjoying

their newly bought jungle gym. | Phillip Dempsey (middle) is

flanked by Klouter Kabouter pre-school teachers Hannadene

Stuurman, Marelise Poggi and Kobus Odendaal; and on

the right: Martina Odendaal, Dirk Odendaal and Shirley

Stuurman, CGA Director for Patensie, Phillip Dempsey,

surrounded by happy pre-schoolers at Klouter Kabouter.

37FEB/MARCH 2020 | INDUSTRY NEWSGEBRUIK PLANTBESKERMINGSPRODUKTE MET VEILIGHEID EN VERANTWOORDELIKE SORG.VOLG AANWYSINGS OP ETIKET TEN ALLE TYE MET TOEDIENING VAN PLANTBESKERMINGSPRODUKTE.

TD 18/142R

Kry meer as net gewasbeskerming

Coragen® bevat chlorantraniliprool (antraniliese diamied) (Rynaxypyr®) Reg. Nr. L8529 Wet Nr. 36 van 1947, versigtig.FMC Chemicals (Edms) Bpk, Posbus 44, Postnet Menlyn, Waterkloof Glen, 0081, Republiek van Suid-Afrika. Tel: +27 12 003 2938.Coragen® en Rynaxypyr® is handelsmerke van FMC Korporasie of sy affiliate. Datum: 08/2018.

Coragen®

i n s e k b e h e e r

aangedryf deur

aktiewe bestanddeel

STAATMAKER VALSKODLINGMOTBEHEER WAT SO SLIM SOOS JY WERK. Vir die boer kom elke seisoen met ’n lys van uitdagings. Gewasbeskerming moet egter nie een van die bekommernisse wees nie. Dit is hoekom ons Coragen® insekbeheer ontwikkel het; een van die mees gevorderde produkte vir insekbeheer in die wêreld. Om slim te werk het nou baie makliker geword danksy die vinnige en lang nawerkende Valskodlingmotbeheer in sitrus. Coragen® insekbeheer bied ’n unieke metode van werking met ’n uitstekende toksikologiese- en omgewingsprofiel. Die nuwe wapen in die geïntegreerde beheer arsenaal teen Valskodlingmot en beter vrugkwaliteit verlaag die risiko van afkeurings vir uitvoervrugte na die meeste uitvoermarkte. Beter gewasbeskerming en bewaring van voordelige insekte – dit is mos wat elke sitrusboer wil hê.

Kontak jou naaste FMC-handelaar om meer uit te vind oor Coragen® insekbeheer.


During the 2019 season, the Soft Citrus Focus Group did an investigation on satsumas, clementines and late mandarin types to identify threats and opportunities to allow better

decision-making opportunities. To this end Dr Graham Barry, in his role as advisor to the variety focus groups, prepared a present-ation on the particular characteristics of the satsuma season. Some of his research is summarised in this article. Similar investi-gations will follow on clementines and late mandarin types.

South African satsuma exports are relatively stagnant and can be seen in the graph right.

The Citrus Growers’ Association (CGA) of Southern Africa growing regions of Boland and Patensie account for over 50% of SA’s total satsuma volumes. The Boland and Cape Midlands have the highest production per hectare. The Western and Eastern Cape areas lying within latitude 32°S to 34°S, account for 84% of area planted and 89% of volumes exported. (See chart right).

Indicative of the relatively stagnant growth of satsuma production is that 256 ha (23%) of the satsuma orchards is older than 25 years of age; 556 ha (49%) is 16 years and older; and 581 ha (51%) were planted between 2004 and 2018.

The satsuma harvest starts in mid- to late-February in the "earliest" regions in Burgersfort and Zimbabwean High-veld and ends mid- to late-May in the Eastern Cape Mid-lands. Thus, southern Africa has a 13-week supply window with a seven-week peak, as illustrated in the chart below:

Satsuma production in SAJOHN EDMONDS

Earlier this year I wrote an article highlighting the pressure bearing on navels and satsumas from various forces. In the case of satsumas, Northern and Southern Hemisphere producers have to navigate increasing pressure from the counter seasonal export offering of the other hemispheres’ high quality late mandarin types.

PRODUCTION SUB-REGION AREA EXPORT VOLUMEREGION PLANTED (Ave. 2004-2018) (ha; 2018) (15 kg cartons)

Western Cape Boland 295 (25,9%) 590 025 (32.3%) Citrusdal 174 (15.3%) 211 511 (11.6%)

Eastern Cape Patensie 238 (20.9%) 401 898 (22.0%) East Cape Midlands 179 (15.7%) 320 093 (17.5%) Sunday's River Valley 68 (6.0%) 107 697 (5.9%)

Mpumalanga Nelspruit 128 (11.2%) 165 868 (9.1%) (Burgersfort Ohrigstad) 21 260 (1.2%)

Limpopo Marble Hall 45 (4%) 21 260 (1.2%)

Northern Cape Vaalharts 6 (0.5%)

Zimbabwe Mvurwi 6 (0.5%)

Total 1 138 ha 1 827 115 (100%)


The early-maturing (mid-February to early-March) satsumas from SA compete head-on with Spanish nadorcott and oth-er late-maturing mandarins from the Mediterranean basin. The late-maturing (mid-June to late-July) – either late-ma-turing cultivars such as aoshima, bela late, satsuma hybrids or late region – will compete with clementines and other mandarins.

Satsumas have some significant advantages over other varieties of mandarin, in that they have generally good production and cartons per hectare, are relatively easy to produce and give typically good per hectare returns. However, the product ma-tures in autumn, prior to onset of cold for natural colour development and pale rinds are sensitive to chilling injury under low-temperature shipping conditions. Degreening is often required due to delayed colour development and they are more prone to chilling injury due to long periods of low-temperature shipping than other varieties. They are also sensitive to sunburn, zebra skin, FCM, sucking and piercing moths, and sour rot.

Soft citrus weekly shipmentsSatsuma harvesting is characterised by a narrow harvest period and minimal overlap with other mandarin varieties in the country. Whilst this is advantageous, any delays in harvesting pushes the window into that of clementines and novas, potentially shortening the satsuma season.

As can be seen in the first graph, satsuma-mandarin supply volumes are stable at around 1.8 m cartons and a long-term projection to 2030 seems optimistic at 2.3 million cartons, i.e. +2.4% per annum growth.

Analysing three years’ average data for 2016-2018 reveals that three principle markets buy 97% of the South Africa satsuma export volume, namely the UK/Ireland 44-50% 800 000-890 000 cartons; Netherlands 24-27% 440 000-480 000 cartons and Russia 19-29% 340 000-570 000 cartons.

The satsuma supply period typically peaks from weeks 12 to 18, i.e. late-March to end-April, with over 90% of volumes shipped (300 000 to 450 000 cartons per week). The early period from week eight to week 11, i.e. late-February to late-March accounts for only 3%, whilst the later period from weeks 19 to 22 (i.e. May) accounts for the remaining 5%.

southern Africa has a 13-week supply window with a 7-week peak, as illustrated in the chart below:

The satsuma supply period typically peaks from weeks 12 to 18, i.e. late-March to end-April, with over 90% of volumes shipped (300 000 to 450 000 cartons per week). The early period from week 8 to week 11, i.e. late-February to late-March accounts for only 3%, whilst the later period from weeks 19 to 22 (i.e. May) accounts for the remaining 5%.

Soft citrus weekly shipments

Satsuma harvesting is characterised by a narrow harvest period and minimal overlap with other mandarin varieties in the country. Whilst this is advantageous, any delays in harvesting

-

500

1 000

1 500

2 000

2 500

-

50 000

100 000

150 000

200 000

250 000

300 000

350 000

400 000

450 000

500 000

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Cumulative 15 kg equivalent cartons (thousands)Cu

rren

t wee

k 15

kg

equi

vale

nt c

arto

ns

Satsumas Passed for Export: Current vs Previous Seasons

2017 Curr Wk Eq. Ctns 2018 Curr Wk Eq. Ctns 2019 Curr Wk Eq. Ctns2017 Cumul. Eq. Ctns 2018 Cumul. Eq. Ctns 2019 Cumul. Eq. Ctns

Satsumas are figuratively caught between a rock (in the Northern Hemisphere late mandarins) and a hard place (in the local clementines and novas following hard on their heels). The key is to be aware of this challenge and to focus on optimising pro-ductivity and pack-outs during the limited time frame. ✤

The chart below illustrates the global satsuma supply periods into the main market of the UK.

Asia/USANew ZealandSouth America Southern AfricaMediterranean

FEB MAR APRIL MAY JUNE JULY AUG SEPT OCT NOV DEC JAN FEB Argentinia - Early Okitsu

Argentinia - Okitsu

Peru - Okitsu

Uruguay - Okitsu Uruguay - Owari

Peru - Owari

NZ - Silverhill/Kiwano

NZ - Aoshima

Spain - Iwasaki Spain - Primosol

Spain - Okitsu Spain - Owari

Israel - Okitsu Turkey - Owari

Stored Spain - Owari

China/Japan Calif Satsumas

Zimbabwe - Miho Wase

Marble Hall - Miho Wase

Escape - Miho Wase Escape - Owari

WCape - Miho Wase WCape - Owari

Satsumas passed for export: current vs previous seasons


Up to the mid 18th century citrus trees were mainly grown from seedlings. With the spread of Phytophthora in sweet oranges began the budding of a scion onto sour orange

as a rootstock. Then, in the early 20th century, Citrus Tristeza Virus (CTV) began devastating many regions where the sweet on sour orange rootstock combination was used. This led to the use of various Trifoliate rootstocks, and at present varieties such as Carrizo and Swingle have gradually become the most popular rootstocks as they ticked most of the boxes, including tolerance to Nematodes. More recently, as citrus development expanded into areas with climates, soil types, water qualities not previously recommended for citrus, the requirements have increased to rootstocks showing tolerance to PH, salinity, drought and tem-perature. Cultivars such as X639 and Sunki Benecke have shown promise in recent years. We now know that rootstocks also bring other advantages to the scion, such as improved yield, quality and size, and some cause earlier or later ripening.

After the devastating arrival of HLB in Florida, rootstocks again came into focus due to their apparent ability to assist scions, as they did with Phytophthora and CTV. The search has been on

in Florida for rootstocks which might help enhance the strength

and disease resistance of HLB-sensitive varieties, as one of a

multi-systems approach to manage the disease.

I visited Florida in January 2014, just after HLB had taken a

firm hold of their orchards. I had been invited by Profs Fred

Gmitter and Jude Grosser to visit and attend a fruit tasting

display at the University of Florida, CREC. After the fruit

tasting we visited the Indian River area. The devastation was

depressing, as Vaughan Hattingh had warned me: “It looks

like aerial sprayed Round Up.” My assessment was that it now

looked like Molopo had been added to the mix. One of the

orchards we visited was on the farm of one of the top local

farmers. The orchard was on 7 ha of five-year-old Star Ruby.

Many trees had already died.

The farm owner showed us a tree that had him confused. We

rounded a bend in the orchard and there it was, an “Escape

Tree”! For whatever reason, the tree was completely asympto-

matic, with excellent colour and crop that would be expected for

an orchard such as this in its early prime.

CGA CULTIVAR BRIEF Rootstocks from Florida

River Bioscience (RB) is a fully owned commercial subsidi-ary of the Citrus Growers Association (CGA) of Southern Africa. Its main objectives are to commercialise innova-

tion, developments and detections arising from Citrus Research International (CRI) research, and to provide the southern Afri-can citrus industry with innovative and useful products aimed at improving global competitiveness. The insect culture estab-lishment facility of RB, in Addo, was recently expanded. The expansion includes a dedicated research laboratory, quality control office, canteen and an additional production area which will allow for advanced research into commercial production systems. These systems will benefit our current development projects including four new viruses. The space is also critical to ensure that the commercial production of our new NPV virus is of the highest quality.

The skilled RB team has grown to make the best use of the development, with five new appointments made in the last two months. Miss Lumka Modonda recently joined RB from XSit, to fulfil a quality control co-ordinator role and Mathew Goddard, who has joined as our production researcher, heads up the team. The expansion will allow for continuous improvement in all areas of production and quality control, which is what we continually strive for and will help secure the future for our business.

XSit monitors on the move XSit, which is wholly owned by RB, aims to provide a solution to the False Codling Moth (FCM) challenge in the citrus industry, through the application of the sterile insect technique (SIT). The distribution of sterile moths in the citrus orchards disrupts the

RIVER BIOSCIENCE BRIEFInvesting in the future ROB ELFICK

JON ROBERTS


Jude muttered, “I still don’t think this is a ‘silver bullet’.” I asked Fred what their thoughts were. He said that the often-repeated dogma regarding HLB and commercial citrus germplasm is that adequate tolerance or resistance does not exist. However, he described other similar incidents of “Escape Trees” that they had discovered in their trial sites. As a result of understandable pressure from the farming community for answers to this devas-tating disease, the UF/CREC Citrus Improvement has undertaken a massive natural HLB screening for potentially tolerant/resistant scions and rootstocks and some field observations suggest that HLB incidence is less common in some citrus cultivars when grown on specific rootstocks. Since then UF CREC has been test-ing these under controlled conditions, to confirm their tolerance to HLB.

On a recent overseas visit, I met with Prof Gmitter again where we discussed the possibility of importing some of these root-stocks that show potential. My argument was that SA needs to trial the rootstock now for commercial viability and also to satisfy the criteria discussed above, i.e. production, resistance to soil borne pathogens and abiotic stresses such as high PH, salinity,

drought etc. In this way we can screen varieties that meet the require-ments for commercial production before HLB arrives in SA, even while their ability/potential for HLB resistance/tolerance is being determined.

Thankfully, Prof Gmitter was open to my suggestion and from there I made contact with CRI’s Paul Cronjé. CRI’s Cultivar and Rootstock Research Committee agreed to prioritise the screening of these rootstocks under SA conditions. Under the leadership of Paul Cronjé, CRI and UF CREC reached agreement in 2019. We are happy to hear that CRI have received import permits for the first rootstocks and the first batch of seed will arrive early this year. The first trees budded with Midknight will be planted out in 2021. We will await the results of these trials with interest in the coming years. ✤

C G A C C

mating process of the wild moths, thus eradicating the pest.

The two main operational functions in the orchards serviced by X-SIT are the releasing of sterile moths and the weekly monitor-ing of both sterile and wild moths captured in the traps. Releases are mostly done by helicopter, but some areas – mostly those under nets –require manual releases which are done by hand and facilitated by using quadbikes for transportation.

Monitoring was also always conducted by quadbike, which add-ed up to 17 monitors. These would require transport by a bakkie-and-trailer configuration to specific areas from where it would be safe to operate the quadbikes, which cannot drive freely on main roads. The movement of quadbikes between farms connected by public roads had always been a logistical challenge. Therefore, it was decided to roll out a plan to replace the quadbikes used

for monitoring with motorcycles. The roll-out started with citrus orchards not covered by nets.

Monitors are in the process of high-level training to facilitate obtaining their licenses, and will be receiving accredited profes-sional driving training, specific to rough terrain. The motorcycles are fully licensed and road legal for use on all national roads in SA. The motorcycles are also specifically designed for low speed farm related operations and the maximum traveling speed on open roads is mechanically limited.

We are very pleased to identify and mitigate risks and reduce complexity in the monitoring process, as well as to provide high quality training and skills development. This will ensure that the services we provide can be more effective and efficient and most importantly, conducted in a safe and responsible manner. ✤

Jon Roberts

44 TEGNOLOGIE HORTGRO | FEB/MAART 2020

This initiative arose from mistakes made by producers in the past,” said André Smit, director of Hortgro Stone, speaking at

the launch. “A mistake in cultivar selection can cost a producer anywhere from R450 000 to as much as R1.6 million per hectare. We at Hortgro Stone realised that our producers can’t continue making mistakes like these — it’s simply too expensive.”

The solution was to establish a programme for the independent evaluation of cultivars. In 2015 Hortgro partnered with Paarl-based compa-ny Provar to develop the capacity needed for large-scale cultivar evaluation. What started as a three-year project culminated in the founding of the Pro-Hort programme.

“The objective of Provar is to generate inde-pendent data that producers can use to reduce the risk associated with planting new cultivars,” said Iwan Labuschagne while addressing attend-ees at the launch. Labuschagne is a geneticist and former apple breeder who founded Provar in 2013. “That’s our goal and of course the goal of the Pro-Hort programme.”

The Hortgro-Provar partnershipThe site at Klipboschlaagte is one of nine that already has trees. Another two sites will be planted in the 2020 season. “Most of our sites are in the Western Cape. There is one in the Langkloof and another in Limpopo,” said Smit. A site is also planned for Tulbagh. During the past season, 3 500 trees were established in the various Pro-Hort orchards.

“The trees we want at these sites are usually phase three selections from the Agricultural Re-search Council’s breeding programme, or culti-vars that are already established abroad that are imported to SA by intellectual property group-ings,” explained Smit. He invited all intellectual property owners to participate in the evaluation programmes at Pro-Hort sites. “Even if a cultivar is not open to everyone, it can still be planted on these sites, but then the cultivar owners just carry the cost of the evaluation, since it’s in a closed group.”

Hortgro supports the Pro-Hort programme by providing capital for the initial development of the trial sites, as well as remunerating the site owners for routine management of the orchards. The site at Klipboschlaagte is part of Smuts Brothers Agri.

“Those of you who have had experimental sites on your farms will know that at best it’s a com-plex matter,” said Smit. “It might seem glamor-ous initially but it can quickly become a burden. So we are very grateful for the sites we have and the willingness of people like Grant Smuts to assist us.”

Hortgro selects three stone and two pome fruit cultivars every year and funds their full semi-commercial evaluation. The evaluation of additional cultivars is funded by other parties. At the end of the process, the cultivars are awarded a certificate by Provar that details all the results of the evaluation. Producers can use this information to decide whether a cultivar is likely to be suited to their farm.

Pro-Hort drives cultivar evaluation

A new programme for the evaluation of pome and stone fruit cultivars was recently launched at Klipboschlaagte near Ashton. The Pro-Hort programme is the result of a collaboration between Hortgro and Provar. Pro-Hort aims to empower producers by generating accurate informa-tion on which to base cultivar selection.

ANNA MOUTON

45FEB/MARCH 2020 | HORTGRO SCIENCE

“This system will only work if producers ask for this evaluation certificate when they are offered a new cultivar,” stressed Smit. “The certificate will empower you with information to decide whether, within your microclimate and your marketing channels, the cultivar offers value.”

Evaluation from the ground upWerner Truter is Provar’s horticulturalist and he described the process of developing the trial orchards. “The trees weren’t just delivered and planted. We worked closely with the site owners and managers to choose the land. The soil was surveyed and an-alysed. We designed the orchards according to this information and corrected and cultivated the soil as indicated.”Each orchard has temperature loggers to precisely measure cold and heat units as well as to register any anomalies that may im-pact tree performance. Orchards also have soil probes to ensure optimal irrigation. Traps are in place to monitor pests such as fruit flies and false codling moth. The sites are securely fenced and access strictly controlled.

Truter has been working closely with technical advisers to ensure the best possible orchard management. This includes seeking guidance on the latest training systems. “We want to train the trees so that we can evaluate them in the way that they are likely to be planted in the future,” he explained.

“Evaluation is the collection of data,” elaborated Carl Hörst-mann, stone fruit evaluator at Provar, “but data is meaningless

without a frame of reference. So what we’ve done with these sites is to create a frame of reference by choosing sites that represent our pome and stone fruit production areas and the variation in climate among those.”

Control cultivars have been planted at each site and new culti-vars are compared against these. Cultivars are trialled on stand-ard rootstocks, as well as preferred rootstocks that have been chosen for their suitability to the specific site and cultivar.

Hörstmann listed the exhaustive criteria by which cultivars are assessed, starting at blossom and taking in everything up to the quality of fruit after an extended storage period. “We generate masses of data which we process using Culteva — our software package — so that it’s useful for both intellectual property own-ers and producers.” Culteva was developed in-house at Provar and is available as a mobile app.

Evaluation is a long game. “It takes six to nine years to estab-lish the cultivars on different rootstocks in different areas,” said Hörstmann. “We at Provar begin to look at production and fruit quality after two to three years and we try to determine as soon as possible whether a cultivar should undergo a full evaluation, or whether it should rather be given a serious iron application in the shape of a chainsaw.”

“This isn’t a quick fix,” confirmed Smit. “It’s a long-term invest-ment but that’s in line with how you as producers live your lives in the context of long-term crops.” ✤

From left at back: Grant Smuts (Smuts Brothers), Iwan Labuschagne (Provar), Anton Rabe (Hortgro CEO), Charl Stander (Hortgro),

André Smit (Hortgro Stone Chairman), Chad van Wyk (Provar). Middle from left: Chantel Adams (Provar), Wilmé van Zyl (Provar).

Front from left: Carl Hörstmann (Provar), Louis van Zyl (Hortgro), Werner Truter (Provar).


IntroductionMoisture loss and shrivel can be a problem with cer-tain SA plum cultivars that are packed and stored for export by sea, or long-term storage. Plastic wrappers, currently used to reduce moisture loss from fruit, were commercialised many years ago. Handling and shipping systems, as well as cultivars and products to control decay, have changed over the years and there are frequent complaints about the occurrence of shrivel. Just 5% mass loss from perishable prod-ucts may cause shrivel (Wills et al., 2007). According to them, produce characteristics influencing moisture loss include aspects such as surface area to volume ratio, with smaller fruit losing water faster. Plant sur-faces also affect water loss, dependant on structure and composition of the waxy cuticle, surface cells and underlying tissues, as well as presence of hairs and lenticels on fruit surfaces. Increasing the relative humidity (RH) of the air around produce reduces vapour pressure difference between products and their surrounds, and hence, less moisture loss occurs. Air movement over produce has a desiccating effect, because it disturbs the boundary air layer. In this layer the vapour pressure is in equilibrium with that of the produce itself, so movement of water out of the produce is slow. With increased air movement, such as during forced-air cooling (FAC), the boundary layer decreases and the rate of moisture loss increas-es. The degree to which moisture loss is reduced by packaging, either by reduction of air movement or increase in RH, depends on the permeability of the package to water vapour transfer, as well as close-ness of containment. Polyethylene (PE) films are good vapour barriers. Wills et al., 2007 emphasises that an increase in RH is associated with increased risk of decay. In the context of long-term fruit storage, this risk must also be taken into consideration when seeking moisture loss solutions.

H W VILJOENExperiCo (Agri-Research Solutions), Stellenbosch, South Africa | [email protected]

This article explores the impact of carton liners and relative humidity in cold stores during accumulation for export on post-storage shrivel levels on Laetitia and African Delight® plums.

Impact of carton liners

AbstractMoisture loss and shrivel can be a problem with certain plum cultivars packed and stored for sea export, or long-term storage. Objectives of this study were to evaluate plastic packaging liner types and relative humidity levels in cold stores during forced-air cooling and accumulation of fruit prior to export, on moisture loss and shrivel for Laetitia and African Delight® plums. Plums were packed in different polyethylene plastic perforated and non-perforated wrapper and perforated bag treatments, and forced-air cooled and accumulated for seven days in cold rooms with and without humidity control. The impact of these treatments on fruit quality after applica-tion of simulated export shipping regimes and subsequent shelf life was determined. The results were quite variable over the three years of study, which is to be expected, since shrivel develop-ment is highly complex and seemingly influenced by multiple factors. As far as mass loss and shrivel control were concerned, humidity control in cold stores that delivered approximately 95% relative humidity during forced-air cooling and accu-mulation, helped maintain plum quality for 35 days’ cold storage. Hence, this is recommended. The impact of liner type on mass loss of plums appeared to be minimised with higher humidity in cold stores. It is suggested to concentrate on further evaluating the 36 x 4 mm perforated bags for plum cultivar prone to shrivel. In the case of African Delight®, further research is required to compare 54 x 2 mm perforated bags to 36 x 4 mm perforated bags for efficacy to control shrivel. The risk of skin cracking on Laetitia plums stored at high relative humidity must be carefully monitored, as should be the development of internal browning as influenced by liners.



1Evaluate different plastic packaging liner types for efficacy to control moisture loss and shrivel on plums, without causing any other negative fruit quality effects. 2

Determine the effect of RH in cold stores used for FAC and accumulation of pallets of plums prior to loading into shipping containers for export, on moisture loss and shrivel on plums.

RESEARCH OBJECTIVES

Materials and methodsThis research was conducted on Laetitia and African Delight® plums in 2017, 2018 and 2019. The fruit were sourced from commer-cial cold stores in Franschhoek, located in the Western Cape, SA. The plums intended for export were harvested by growers, accord-ing to the statutory maturity standards, using flesh firmness and total soluble solids (TSS) as primary indices. Fruit was warm-packed into the various packaging liner treatments on the day of harvest and subjected to FAC as per individual cold store practice. The five liner treatments tested on Laetitia were: no-liner, standard perforated plum wrapper (48 x 6 mm), non-perforated wrapper and perforated bags with 36 x 4 mm and 72 x 4 mm hole config-urations. In the case of African Delight®, the four treatments applied were: no-liner and perforated bags with 18 x 4 mm, 36 x 4 mm and 72 x 4 mm configurations. The wrappers and bags were manufactured in high density polyethylene (HDPE) format with thickness of 20 and 15 microns, respectively. The plums were packed on pulp trays in standard double layered 5 kg D051 cartons with a 300 x 400 mm box footprint.

Split samples, each comprising five replicate cartons of all the packaging liner treatments were subjected to low and high RH cold stores immediately after packing. The fruit was held under these conditions for the first seven days of cold storage during which FAC was con-ducted, and a simulated accumulation period implemented. In total, the plums were cold stored for 35 days. The accumulation period simulated the “holding” stage of pallets of fruit prior to sea export. For each population

of fruit tested, the same low and high humi-dity cold store was used for both FAC and accumulation. The “low” RH cold rooms had no humidity control equipment and an air temperature set point of -1.0°C.

The “high” RH cold rooms were fitted with humidifiers and also set at -1.0°C. After the seven-day accumulation, fruit was transferred to cold stores without specialised humidity control (± 92.5% RH) for the remainder of the cold storage period. A PD7 dual-temperature regime was used in the case of Laetitia (10 d @ -0.5°C, 7 d @ 7.5°C, 18 d @ -0.5°C) and a PD1 single-temperature regime (35 d @ -0.5°C) was used for African Delight®. A subsequent shelf life comprising five days at 10°C was applied for both cultivars.

Fruit maturity at packing was assessed by measuring flesh firmness (11.0 mm plunger - kg), TSS (%) and titratable malic acid (%). Fruit quality after cold storage, both at the start and end of shelf life, was ascertained by mea-suring mass loss (fruit mass at harvest com-pared to after storage), shrivel stretching over the shoulders of fruit, flesh firmness, decay and internal quality. The internal disorders gel breakdown [GB], internal browning [IB]) and over-ripeness [OR] were classified as defined by Taylor (1996). Five single carton replicates were used per treatment. The start and end of shelf life data were analysed separate-ly, using Two-way ANOVA’s with Factor (A) liner packaging type and Factor (B) humidity control. Wrappers and/or bags were opened at the start of shelf life to simulate commercial practice. Half of the fruit in each carton were examined before shelf life and the remainder after shelf life.


Results and discussionThis research was conducted in commercial cold stores. In retrospect, it may have been better to do preliminary testing under laborato-ry conditions, to guarantee the desired exper-imental humidity and temperature conditions in cold stores during FAC and accumulation. In

some instances, the target high RH conditions in cold stores fitted with humidifiers were com-promised because warm fruit was frequently transferred into the room for purposes of FAC. This necessitated frequent opening of the cold store doors rendering it impossible to achieve high RH levels and compromising temperature control. In one instance the temperature was

Table 1: Quality of Laetitia plums packed in different liner treatments, held without (N) and with (Y) relative humidity control (74.2% vs

94.9% RH) in the cold rooms for seven days’ accumulation at the start of storage, as determined after 35 days’ dual-temperature cold storage

1 Mass loss for 36 fruit is shown and GB = Gel Breakdown, IB = Internal browning and OR = Over-ripeness2 Values in same row followed by different letters indicate significant differences (P<0.05) according to the LSD test3 Humidity control for seven days’ simulating accumulation period: N = average of 74.2% RH, Y = average of 94.9% RH

Table 2: Quality of Laetitia plums packed in different liner treatments and held without (N) and with (Y) relative humidity control

(74.2% vs 94.9% RH) in the cold rooms for seven days’ accumulation at the start of storage, as determined after 35 days’

dual-temperature cold storage, plus a shelf life of five days at 10°C

1 Mass loss for 36 fruit is shown and GB = Gel Breakdown, IB = Internal browning and OR = Over-ripeness2 Values in same row followed by different letters indicate significant differences (P<0.05) according to the LSD test3 Humidity control for seven days’ simulating accumulation period: N = average of 74.2% RH, Y = average of 94.9% RH

Parameters1 Humidity Liner packaging type (A) Humidity control3 Prob.>F2

control3 (7 days) (B) (7 days) No liner 48 x 6 mm Non- 36 x 4 mm 72 x 4 mm Perforated perforated Perforated Perforated N Y A B A x B wrapper wrapper bag bag

Mass loss (g) N 67.6f 51.0e 44.7de 21.0ab 25.8abc - - 0.0000 0.0020 0.0395

Y 39.5cde 33.8bcd 32.1abcd 16.8a 31.4abcd

Flesh firmness (kg) N+Y 3.2a 2.8bc 2.8c 3.0ab 2.8c 2.8b 3.1a 0.0011 0.0000 0.0655

Decay (%) N+Y 0.0 0.5 0.3 0.5 0.3 0.2 0.4 0.7775 0.4766 0.5284

Shrivel (%) N+Y 18.4 18.7 17.2 15.8 11.6 19.1b 13.6a 0.3221 0.0235 0.751

IB (%) N+Y 3.0b 0.0a 0.5a 1.0ab 0.0a 0.6 1.2 0.0443 0.3816 0.1802

GB (%) N+Y 1.0 9.0 2.0 7.0 4.0 5.8 3.4 0.3354 0.3916 0.2598

OR (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NS NS NS


control3 (7 days) (B) (7 days) No liner 48 x 6 mm Non- 36 x 4 mm 72 x 4 mm Perforated perforated Perforated Perforated N Y A B A x B wrapper wrapper bag bag

Mass loss (g) N 59.3d 60.8d 53.9d 28.1ab 35.1b - - 0.0000 0.0000 0.0166

Y 44.5c 36.3bc 30.7ab 23.4a 23.7a

Flesh firmness (kg) N+Y 2.7 2.3 2.7 2.5 2.7 2.4b 2.8a 0.2901 0.0069 0.5087

Decay (%) N+Y 0.0 0.0 0.3 0.0 0.3 0.0 0.2 0.5638 0.1650 0.5638

Shrivel (%) N 31.4ef 34.0f 31.2ef 28.7def 17.3bcd 0.1710 0.0000 0.0054

Y 12.5abc 8.9ab 20.6bcde 0.5a 21.9cdef

IB (%) N+Y 1.5ab 12.0bc 1.0a 13.5c 1.5ab 7.2 4.6 0.0438 0.4208 0.1337

GB (%) N+Y 0.0 1.0 0.0 3.5 1.5 1.8 0.6 0.1783 0.2371 0.2091

OR (%) N+Y 0.0 0.5 0.5 0.0 0.0 0.4 0.0 0.5639 0.1650 0.5638


Table 3: Quality of African Delight® plums packed in different liner treatments and held without (N) and with (Y) relative humidity

control (89.9% vs 95.6% RH) in the cold rooms for seven days’ accumulation at the start of storage, as determined after 35 days’

single-temperature cold storage at -0.5°C

1 Mass loss for 36 fruit is shown and GB = Gel Breakdown, IB = Internal browning and OR = Over-ripeness 2 Values in same row followed by different letters indicate significant differences (P<0.05) according to the LSD test3 Humidity control for seven days after packing, simulating accumulation period: N = average of 89.9% RH, Y = average of 95.6% RH

Table 4: Quality of African Delight® plums packed in different liner treatments and held without (N) and with (Y) relative humidity

control (89.9% vs 95.6% RH) in the cold rooms for seven days’ accumulation at the start of storage, as determined after 35 days’

single-temperature cold storage at -0.5°C plus a shelf life of 5 days at 10°C

1 Mass loss for 36 fruit is shown and GB = Gel Breakdown, IB = Internal browning and OR = Over-ripeness2 Values in same row followed by different letters indicate significant differences (P<0.05) according to the LSD test3 Humidity control for seven days after packing, simulating accumulation period: N = average of 89.9% RH, Y = average of 95.6% RH

approximately 3°C higher than the -1°C set point.

While this research was conducted over three years, only the 2018 seasons data for Laetitia (Tables 1 and 2) and African Delight® plums (Tables 3 and 4) will be shown to illustrate the observed cold store RH and packaging liner impact on post-storage plum quality. The full

research report is available from Hortgo Science (Viljoen, 2019).

At intake, the Laetitia plums exhibited a flesh firmness of 6.3 kg, TSS of 10.4% and a malic acid of 1.49% (data not shown). While the flesh firmness complied with the export standard, the TSS was below the 11% minimum. In the case of African Delight®, the plum maturity was within


control3 (7 days) (B) (7 days) No liner 18 x 4 mm 36 x 4 mm 72 x 4 mm Perforated Perforated Perforated N Y A B A x B bag bag bag

Mass loss (g) N+Y 42.2b 12.0a 13.4a 17.4a 24.7b 17.9a 0.0000 0.0013 0.0724

Flesh firmness (kg) N+Y 7.8 8.0 7.9 7.9 8.0 7.8 0.9878 0.4741 0.1238

Decay (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 NS NS NS

Shrivel (%) N+Y 8.3 7.8 6.9 8.3 8.6 7.1 0.9677 0.5021 0.0972

IB (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 NS NS NS

GB (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 NS NS NS

OR (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 NS NS NS


control3 (7 days) (B) (7 days) No liner 18 x 4 mm 36 x 4 mm 72 x 4 mm Perforated Perforated Perforated N Y A B A x B bag bag bag

Mass loss (g) N+Y 48.9b 19.4a 22.1a 25.0a 31.8b 25.9a 0.0000 0.0222 0.2616

Flesh firmness (kg) N+Y 7.0 7.5 7.0 7.4 7.4 7.1 0.6411 0.3877 0.5719

Decay (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 .NS .NS .NS

Shrivel (%) N 13.3b 8.9ab 11.1b 11.1b - - 0.0516 0.0500 0.0395

Y 12.2b 13.9b 0.0a 0.0a

IB (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 .NS .NS .NS

GB (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 .NS .NS .NS

OR (%) N+Y 0.0 0.0 0.0 0.0 0.0 0.0 .NS .NS .NS


the optimum range, with a flesh firmness of 9.6 kg, TSS of 19.2% and malic acid content of 0.91% (data not shown).

After 35 days’ cold storage, at the start of shelf life, clear trends relating to mass loss which are indicative of moisture loss, were evident with Laetitia plums (Table 1). At 67.6 g, the mass loss from plums in the no-liner treatment was significantly higher where no humidity control was applied in the cold store (74.2% RH), com-pared to 39.5 g mass loss in the cold store with humidity control (94.9% RH). The liner packag-ing type had a more profound effect on mass loss when the plums were cooled and accumu-lated at the lower RH, in the cold store without humidity control, compared to the higher RH. At low humidity, the perforated bags limited moisture loss significantly better than wrap-pers, and both these liner formats gave better control of moisture loss than the no-liner treat-ment. In this comparison across treatments accumulated in the cold store without humidity control, differences in bag perforation config-uration had no significant effect on mass loss. The liner format, namely: whether wrapper or bag, was a more dominant influence. With humidity control in the cold store that result-ed in higher RH, the liner packaging type had less impact on moisture loss. This suggested that under conditions of high humidity in cold rooms (and probably shipping containers), the impact of liner type on moisture loss may be reduced. The non-pooled mass loss results showed a somewhat clearer picture of the influence of humidity control and liner pack-aging type, than the shrivel data that were pooled due to a non-significant interaction. With shrivel, the liner type had no significant impact on incidence. However, shrivel levels were significantly lower (13.6%) under condi-tions of high RH in the cold store during FAC and accumulation, compared to where the RH was lower (19.1% shrivel). Flesh firmness was significantly higher, albeit a negligible 0.3 kg, for fruit accumulated under higher humidity conditions. Small differences were also record-ed across liner treatments. IB was significantly higher, albeit at low levels, in the Laetitia plums packed without a liner. It is postulated that this may have been a consequence of fast-er cooling without the air barrier effect created

by liners. It is well known that fast cooling of Laetitia may exacerbate internal fruit quality disorders (de Kock et al., 2006). This effect was lost over shelf life (Table 2). Decay and GB were recorded at relatively low levels, with no significant differences across treatments, while no OR was detected (Table 1).

After 35 days’ cold storage, plus five days’ shelf life, the mass loss from Laetitia plums packed in perforated bags was lower compared to the no-liner and wrapper treatments, irrespective of whether humidity control was applied or not (Table 2). In most cases this difference was significant. Similar to the start of shelf life, best overall control of mass loss occurred for fruit packed in the 36 x 4 mm perforated bags. The shrivel levels across treatments were lower in the plums stored with humidity control (94.9% RH), compared to those accumulated without humid-ity control (74.2% RH). Once again, this showed the importance of maintaining a high RH during FAC and accumulation to limit shrivel in Laeti-tia plums after shipping to overseas markets. Overall, the best shrivel control was achieved for plums accumulated at high RH using 36 x 4 mm perforated bags. Flesh firmness was significantly higher for the plums stored under high RH conditions, compared to low RH, with no differences across liner types. Decay, GB and OR levels remained low across treatments at the end of shelf life. For some inexplicable reason, IB was higher in plums stored in the standard perforated wrapper (12.0%) and the 36 x 4 mm perforated bags (13.5%) compared to the other treatments. This aspect should be carefully mo-nitored in semi-commercial trials.

At the end of 35 days’ cold storage, the mass loss from African Delight® plums packed in perforated bags was significantly less than with the no-liner treatment (Table 3). No significant differences in mass loss occurred across the different bag perforation treatments. However, there was an increase in moisture loss with an increase in the number of perforations per bag. Pooled data revealed that mass loss from plums held in the accumulation cold store without humidity control (89.9% RH), was significantly higher than where humidifiers were used (95.6% RH). Despite differences in mass loss across liner packaging type and humidity control treatments, shrivel levels across treatments were low (<9%)

50


with no significant differences between treat-ments. Flesh firmness did not differ between treatments, and no decay, GB and IB were recorded at the start of shelf life.

After 35 days’ cold storage plus five days’ shelf life, the mass loss from African Delight® plums followed the same profile as at the start of shelf life. The mass loss from plums in the perforated bag treatments was significantly lower than with fruit packed with no liner (Table 4). Fruit stored under humidity control (95.6% RH) lost signif-icantly less moisture than those accumulated in a store without humidity control (89.5% RH). Shrivel was significantly lower for fruit packed in the 36 x 4 mm and 72 x 4 mm perforated bags and accumulated in the cold room with higher humidity, compared to all the other treatments, except fruit packed in 18 x 4 mm perforated bags and accumulated at the lower RH. One would expect that the plums packed in the 18 x 4 mm perforated bags and accumulated in the cold store with humidity control would exhibit the lowest shrivel due to less perforations and higher RH, but this was not the case. The reason for this is unclear. Commercially, 54 x 2 mm perforated 20 micron LDPE bags with a total vent area of 170 mm2 per bag (5 kg carton) are sometimes used for African Delight®. Further research is required to compare efficacy of this bag type to the 36 x 4 mm bags tested in this study, which have a vent area of 452 mm2. Flesh firmness did not differ significantly between treatments, and no decay, GB, IB and OR were detected.

While decay development is known to be a higher risk on stored fruit at high humidity (>95%), decay levels on plums in this study were low. It is presumed that this is due to good post-harvest decay control that is achieved through use of effective products and applications.

Consequently, decay control efficacy must be taken into consideration when any changes are made to fruit packaging liners or RH levels in the air, surrounding the produce.

ConclusionsFor Laetitia plums, as far as mass loss and shrivel control were concerned, 95% RH during FAC and accumulation at the start of storage helped optimise plum quality after 35 days’ cold storage. Regarding optimal liner packaging to control shrivel specifically, the variable results recorded over the three years of study, made it difficult to identify the single best option. The impact of liner type packaging on mass loss appeared to be minimised at higher humid-ity in cold stores. It is suggested to expand commercial testing of 36 x 4 mm perforated bags, used in combination with good humidity control during FAC and accumulation. The risk of skin cracking on Laetitia plums stored at high RH must be carefully monitored, and so should development of internal browning as influenced by liners.

In the case of African Delight® plums, the 36 x 4 mm perforated bags showed promise in combi-nation with good humidity control during FAC and accumulation. Further research is required to compare the efficacy of 36 x 4 mm perforated bags to 54 x 2 mm perforated bags.

Overall, it is likely that different plum cultivars react differently to moisture loss prevention technologies such as humidity control in cold stores and application of liners. Hence, culti-var-specific testing is recommended. This is es-pecially important from an environmental point of view, where plastic – even if it is recycled – should be avoided, unless absolutely necessary for fruit quality maintenance. ✤

ReferencesDe KocK, V.A., KhumAlo, P., DAViDs, J. AnD Jooste, m. 2006. Forced-air cooling recommendations for plums. SA Fruit Journal 5(3): 17.

tAylor, m.A. 1996. Internal disorders in South African plums: A research review, revision of internal disor-der definitions and advice on how to prevent internal disorders in export plums. Deciduous Fruit Grower 46(9): 328-335.

VilJoen, h. 2019. Final Report – Identify and test improved packaging systems as well as humidity control in cold stores to reduce moisture loss and shrivel in plums. Hort-gro PL 03-17.

Wills, r.B.h., mcGlAsson, W.B., GrAhAm, D. AnD Joyce, D.c. 2007. Water Loss and Humidity. In: Postharvest – An intro-duction to the physiology and handling of fruit, vegeta-bles and ornamentals (5th Edition), CABI, UK, pp.67 – 82.

AcknowledgementsThanks to the SA Stone Fruit Producers Associa-tion (SASPA) for financing this research, HORTGO for placing the research at ExperiCo, and Dr Martin Taylor for assistance with the preparation of this publication.


The orchard may not be breaking records, but on less than substandard soil and in seasons with poor winter chill and sum-mers with very little water, it delivered

above average harvests,” says Bestuis producer Gys van der Westhuizen.

Since its first harvest in 2016, this plum orchard has delivered more than 5000 cartons/ha, annually. From its third leaf up to its fifth leaf, a cumulative yield of 119 tonnes/ha has been harvested, delivering an average of 38.7 tonnes/ha over the three seasons. For the next season, they want to improve these numbers even fur-ther, with an aim of 40 tonnes/ha.

“We try to take care of this orchard as best as possible to ensure consistently good harvests for as long as possible.” Van der Westhuizen and the team have learnt valuable lessons so far.

Handling the heatAlong with the rest of the industry, Bestuis Farm’s orchards also experienced challenging climate and drought conditions. Luckily, their choice of cultivar is genetically more resistant to the difficult climatic conditions thrown their way in recent years. According to Van der Westhui-zen, this is the single biggest factor that contrib-utes to the orchards’ success.

In general, Bestuis Farm uses micro-irrigation, with the added advantage that it slightly cools down the environment in extreme heat. They also use pulse irrigation in heat wave conditions.

“In a situation where there was very little water

available, we had to adjust our irrigation sched-ule,” says Van der Westhuizen. “We applied two or three short one-hour irrigations week-ly, followed by a single three-and-a-half hour irrigation.”

Organic materials like off-cuts and wood chips on their tree row ridges help keep soil temper-atures cool during severe heat. A large number of wooden off-cuts were also placed under the trees right before the drought. Van der West-huizen believes the placement of these off-cuts made a huge difference in recent drought years.

Strategies for success “With delicate and correct techniques, he achieved much more than many of his co-pro-ducers on better sites,” says technical advisor Petru du Plessis about Van der Westhuizen’s efforts. “His success lies in the fact that he produces large harvests by producing large fruit, and not by producing as many fruit.”

According to Van der Westhuizen, it was a “lucky accident” that led to this successful approach. Poor cross-pollination occurred, since flowering of the cross pollinator and the main cultivar do not always overlap very well. While one might think that there is hopelessly too few fruit, fruit size was great – an average of 75% AAs and greater.

“A light set is certainly a risk,” Van der Westhui-zen admits. “But I believe if you want to reap big fruits, you have to start thinning very early or have a light set from the start.” ✤

BAKGATBOORD SERIES

BESTUISFARM

Faced with a challenging

environment and difficult

climate conditions, the

team on Bestuis Farm in

Klapmuts had their work

cut out. Despite difficult

circumstances such as

limited water and subpar

soil compared to the rest

of the valley, this plum

orchard continued to

deliver a consistently

good tonnage over the

past three seasons.

GRETHE BESTBIER

1. Tree volume:The team tries to maintain a three-dimensional tree shape. Side branches are bent into the tractor row to intercept maximum sunlight. Even with very short side shoots, which will accom-modate a picking platform, they still try to beat a two-dimensional flat training system in terms of volume. There are simply more bearing posi-tions for fruit, says Van der Westhuizen.

2. Irrigation and fertilisation The farm fertilises through its irrigation water. They keep a close eye on the orchard and adapts irrigation and fertilisation according to conditions. Van der Westhuizen believes that no fertiliser recommendation is cast in stone. He also asks for advice and constantly consults with his technical adviser and other farmers and experts.


BAKGAT QUICK FACTS:FARM: BESTUIS FARM, KLAPMUTS

Producer: Gys van der Westhuizen

Technical Advisor: Petru du Plessis

Rootstocks: Maridon

Cultivar: For licensing reasons, the cultivar cannot be named. What can be said is that it is a well-adapted Israeli cultivar, imported and managed in SA, on behalf of the cultivar developer in Israel.

Plant date: 2013

Plant spacing: 1.5 x 3.5 m, 1 905 trees/ha0.75 x 4 m (V-system), 3 333 trees/ha

Production figures: 3rd leaf (2016) – 42.5 t/ha with 84% pack-out 4th leaf (2017) – 40.5 t/ha with 78% pack-out5th leaf (2018) – 36 t /ha with 86% pack-out

3. Rest breaking Van der Westhuizen gives his technical advisor “all the credit” for rest breaking decisions. “[Petru] is a rest breaking expert on plums. We follow his advice as far as rest breaking is concerned.” A tree that is not properly awake does not have enough leaves or breaks and cannot produce enough photosynthetic prod-ucts to yield optimum fruit size.

54 TEGNOLOGIE SATI | FEB/MAART 2020

CONTROL OF MALES WITH DIFFERENT INSECTICIDES UNDER SEMI-LABORATORY CONDITIONSAs Margarodes males are very small-winged insects, already registered insecticides to control similar small-winged pests like fruitfly, pumpkin fly, leafhoppers, etc. were evaluated. Seven insecticides were evaluat-ed in total. Information on these products are listed in Table 1. Males were collected with small brushes in an infested vineyard at Klein Pella near Pofadder in the Northern Cape, and 6 - 10 individuals were placed in a plastic container (24 x 19 cm and 11 cm deep) and the bottom was covered with a 2 cm layer of soil. Each insecticide was sprayed onto the males with small 1L hand spray guns at five presses per repli-cate, to standardise the volume of spray mixture per product. Directly after treatment, the container was covered with a plastic lid perforated with very small holes and placed in a shady area in the vineyard. After three hours it was investigated if the males were still alive, according to any movement. The whole process was repeated four times for each insecticide.

Table 1: Information on insecticides evaluated for

control of adult males and females of M. prieskaensis

Active Trade- Formulation Dosage ingredient name per 1 L water

Alpha- Cypermethrin Ultra Kill 60 g/l ec 4 ml Deltamethrin Decis 25 g/l ec 1 ml Dichlorvos Divos 1000 g/l ec 1 ml Chlorpyrifos Dursban 480 g/l ec 1 ml Indoxacarb Steward 300 g/kg wg 1 g Spinetoram Delegate 250 g/kg wg 1 g Acetamiprid Mospilan 222 g/l wg 1 g

RESULTSThe percentage control obtained with each insecti-cide is shown in Table 2. Fantastic control of 100% was obtained with Ultra Kill, as well as Divos. Mospilan also obtained almost 100% control.

Chemical control of male Margarodes prieskaensis

The aim of this study was therefore to evaluate different contact pesticides to control the males before mating. Applications were made directly to the males at the soil surface during June/July, when no leaves are present and no irrigation is applied.

Dr André de Klerk: Private Consultant, CA Science, Stellenbosch | Email: [email protected]

INTRODUCTIONMargarodes are subterranean scale insect pests that attack plant roots. Of the 10 species known in SA, five attack grapevines while the rest mainly occur on grasses. Margarodes prieskaensis is widespread within the Orange River irrigation area in the Northern Cape around Pella, Blouputs, Kakamas, Kei-moes, Upington, Groblershoop, Prieska, Douglas and Hopetown. The specie was recently also recorded on table grapes in Mpumalanga [Lephalale (Ellis-ras), Mokopane (Potgietersrus) and Groblersdal], and Southern Namibia near Noordoewer. Serious damage is being caused in table, raisin and wine grape vineyards on a variety of rootstocks. The feeding on the roots causes retarded growth and low yields, resulting in uneconomic production and eventual death of the vines. Young vines planted in infested soil can be killed within four years. As no pesticide is presently registered for the control of Margarodes and no biological control methods or resistant rootstocks are known, infested soils become unsuitable for economic grape production in the Northern Cape.

M. prieskaensis is the only SA Margarodes specie that reproduces sexually with females and winged males, emerging once a year to the soil surface to facilitate mating. This opens the possibility to control this specie by using contact insecticides to kill the males. Without mating, no fertile eggs can be produced and as each female can lay up to 1 000 eggs per season, the population could decrease very rapidly. If the males could be killed with con-tact insecticides before mating, unfertile eggs would reduce the population significantly. All residue problems will also be solved because no leaves are present when males occur (June/July). A further positive action will be if the same product could also kill the females.

55FEB/MARCH 2020 | SATI TECHNOLOGY

Males are strongly attracted by females for mating on the soil

surface. Female (right) males (left).

Dursban and Decis gave good control of 80% and more. However, poor control was obtained with Delegate and Steward.

Table 2: Percentage control of males with different

insecticides, under semi-laboratory conditions

Treatment Replicates Average I II III IV % control Untreated 0 0 17 0 4.3 control Ultra Kill 100 100 100 100 100 Divos 100 100 100 100 100 Mospilan 100 83 100 100 95.8 Dursban 100 100 50 100 87.5 Decis 100 60 100 67 81.7 Steward 50 0 66 67 45.8 Delegate 67 17 33 33 37.5

CONTROL OF FEMALES WITH DIFFERENT INSECTICIDES UNDER SEMI-LABORATORY CONDITIONS To determine the effect of each of the seven different insecticides on the control of females, the same technique with the plastic containers was applied as for males. Five replicates per treatment were evaluated. The soil in each plastic container was sieved after treatment, to ensure that females did not move underground.

RESULTSThe percentage control obtained with the same sev-en insecticides is shown in Table 3. As in the case of males Ultra Kill as well as Divos also gave 100% control of females. Dursban and Decis gave good control of 84% to 88%. Mospilan gave average con-trol of 72% while Delegate and Steward performed badly with only 25% control.

Table 3: Percentage control of females with differ-

ent insecticides under semi-laboratory conditions

Treatment Replicates Average I II III IV V % control

Untreated Control 0 0 0 0 0 0 Ultra Kill 100 100 100 100 100 100 Divos 100 100 100 100 100 100 Dursban 100 100 90 50 100 88.0 Decis 80 70 70 100 100 84.0 Mospilan 20 70 70 100 100 72.0 Delegate 17 50 0 33 33 26.6 Steward 30 20 20 17 33 24.0

SIMULTANEOUS CONTROL OF MALES AND FEMALESThe average control of males as well as females per insecticide of five of the most successful products evaluated is shown in Table 4.

Table 4: Percentage control of males and

females with different insecticides under

semi-laboratory conditions

Insecticides Males Females Average % control of both stadia

Ultra Kill 100 100 100 Divos 100 100 100 Dursban 87.5 88.0 87.7 Mospilan 95.8 72.0 83.9 Decis 81.7 84.0 82.8

Excellent control of 100% was obtained with Ultra Kill, as well as Divos. Good control was also obtained with Dursban (88%), Mospilan (84%) and Decis (83%). Anyone of these insecticides could thus be used to kill males and females simultane-ously during the mating process (Figure below).

CONTROL OF MALES UNDER SEMI-COMMERCIAL CONDITIONSMales were collected in a vineyard at the farm Raap en Skraap, situated 180 km from Klein Pella. Methods were the same as mentioned before, except that the plastic containers were not covered with a lid after treatment of the males.


The open containers were kept in the vineyard to maintain the weather conditions. After only 30 min-utes the males were evaluated for any sign of life.

Two of the insecticides that gave 100% control under semi-laboratory conditions viz Ultra Kill and Divos, were evaluated and the results are shown in Table 5. Both products gave excellent control of 100% each.

Table 5: Percentage control of males with two

different insecticides under semi-commercial

conditions

Treatment Replicates Average I II III IV % control

Untreated Control 0 0 0 0 0 Ultra Kill 100 100 100 100 100 Divos 100 100 100 100 100

CONTROL OF MALES UNDER COMMERCIAL CONDITIONS WITH TRACTOR APPLICATIONTwo wooden frames were built with 5 cm wide strips, each comprising two squares of 20 x 30 cm. These frames were placed in the vineyard on top of areas where females occur on the soil surface. The two frames were placed in line and 2-3 metres apart from each other in the middle of the row.

A tractor mounted with a herbicide spray applicator with eight spray heads was used to apply Divos insecticide at a dosage of 100 ml per 100 L water. The spray applicator was mounted at the back of the spray tank pulled by the tractor. The spray appli-cator covered the whole area between two rows, including half of each “bankie”. The tractor’s speed was very slow, driving over the wooden frames. This action was repeated for a second application.

RESULTSTwo hours after treatment all males in each square in the two wooden frames were collected to decide if they were dead or alive. The results are shown in Table 6. Although the number of males was rather low, all males were dead and 100% control of males was obtained with this commercial method of appli-cation. When the spray applicator is connected at the back of the spray tank the possibility exists that the movement and noise of the tractor could be the reason for males to be disturbed and to fly away before the insecticide could contact them.

Table 6: Number of live males before and after

treatment, and percentage control with Divos under

commercial conditions with tractor application

Treatment Replicates Average I II III IV

Untreated Control 9 5 6 8 7 Divos 0 0 0 0 0 % Control 100 100 100 100 100

CONTROL OF FEMALES UNDER SEMI-COMMERCIAL CONDITIONSTwo wooden frames were built, each consisting of two squares 20 x 30 cm. The wooden strips were only 5 cm wide. These frames were placed in the vineyard on top of areas where females occur on the soil surface. The two frames were placed in line and 2 - 3 meters apart from each other. Ultra Kill insecticide was sprayed with small 1 L hand sprays on top of the females in each square of the frames. (No males were present at the time of treatment.) The four squares represented four replicates per treatment.

All females present in each square were counted at 10h00 in the morning and the whole population was alive. At 11h00 all females were treated as mentioned above. Three hours after treatment no females were present on the soil surface, indicat-ing that they had burrowed downwards. Females usually do this daily, returning to the soil surface the next day for mating.

However, the following day again between 10h00 and 11h00, no females were present on the soil surface, indicating that all had died underground. The soil underneath one of the squares, originally with 131 females on the surface before treatment, was dug out to a depth of 15 cm and all the fe-males were found dead.

RESULTSAs shown in Table 7 the female population was exceptionally high, with an average of 103 females present per square of 660 cm2, with a maximum of 152. With only one spray treatment, 100% control was obtained in all four replicates.

57FEB/MARCH 2020 | SATI TECHNOLOGY

Table 7: Number of live females before and after

treatment with Ultra Kill, and percentage control

under semi-commercial conditions


Untreated Control 130 152 78 52 103 Ultra Kill 0 0 0 0 0 % Control 100 100 100 100 100

CONTROL OF FEMALES UNDER COMMERCIAL CONDITIONS WITH TRACTOR APPLICATIONThe same actions were applied with a herbicide spray applicator, as described for the commercial control of males. The same insecticide, Divos, at the same dosage and wooden frames were also used. The herbicide spray applicator also covered the whole area between rows, but was mounted in front of the tractor. This will solve the problem that males could fly away and females may move down into the soil before the chemical could reach them. The experiment was conducted at the farm Raap en Skraap, while the control of males with tractor application was done at the farm Klein Pella, 180 km from Raap en Skraap.

RESULTSThe females per square in the wooden frames were collected two hours after treatment to determine if they were alive. (There were no males present at that stage.) The results are shown in Table 8.

Table 8: Number of live females before and after

treatment with Divos and percentage control under

commercial conditions with tractor application


Untreated Control 20 42 26 34 31 Divos 0 0 0 0 0 % Control 100 100 100 100 100

A high and even number of females were present in each square (replicate). All of these were dead after treatment and 100% control of females was obtained with this commercial method.

CONTROL OF FEMALES WITH BODY NOT TOTALLY ON SOIL SURFACEAt the time of emergence of females to the soil surface for mating, a relatively high percentage of the population turnaround protruding only about 30% of the body length above the soil surface (Figure below). The success of control by spraying

Females with only part

of their body above

the soil surface during

mating


only such a small body area was evaluated under semi-commercial conditions. A small area of the soil surface with both kinds of protrusion was sprayed with Ultra Kill and small hand sprays, as mentioned previously. Directly after treatment 20 individuals of each position were collected in four different glass containers. After four hours the females in each container were evaluated for any sign of life, and to determine the percentage control.

RESULTSAs shown in Table 9, the total dorsal body con-tact treatment produced 100% control at all four replicates. The same results were obtained, where only about 30% of the body length was treated. Chemical control of females with contact insecti-cides will thus not be negatively affected if females protrude only part of their abdomen above the soil for mating.

Table 9: Percentage control of females with

Ultra Kill at different body contact coverage during

treatment, under semi-commercial conditions

Body Replicates Average % contact I II III IV control coverage

Full dorsal body 100 100 100 100 100 30% of body length 100 100 100 100 100

ACKNOWLEDGEMENTSMr Wollie Wolmarans, Manager Klein Pella Farm, Karsten Group,

Northern Cape.

Mr Hawie Moller, Manager Raap en Skraap and Karsten Group, Northern Cape for using their vineyards, machinery and regular provi-

sion of labourers over a period of three seasons.

The funders of the research:

Department Agriculture, Land Reform and Rural Development, Northern Cape

South African Table Grape Industry

Dried Fruit Technical Services

Contact: Dr André de Klerk: [email protected]

SUMMARYMargarodes is an underground insect pest that attacks the roots and causes tremendous damage to especially grape vines. Underground chemical control and leaf coversprays usually cause residues in the grapes that are unacceptable for the export market of table grapes. No insecti-cide is presently registered for control and many hectares are presently taken out and replaced with other fruit cultivars.

Margarodes prieskaensis occurs wide-ly in the Northern Cape area and is the only margarodes specie that reproduces sexually with males and females that move from the roots to the soil surface for mat-ing. If males could be killed with contact insecticides before mating, unfertile eggs would reduce the population significantly. All residue problems will also be solved, because no leaves are present when males occur (June/July). A further positive action will be if the same product could also kill the females.

Because of the urgency of the problem seven contact insecticides were evaluated over three seasons for the control of males, as well as females with four evaluation methods. Five of these pesticides gave very good control of 80% to 100% of males, as well as females.

Two of these chemicals that gave 100% control were also evaluated by commercial tractor application and 100% control was again obtained of males and females.

The results show clearly that excellent control of Margarodes males and females could be obtained by various contact pesticides. Also, that both stages could be killed by a single application. Further-more, with this method of control only one annual application of the chemical is required during June/July, when they are present on the soil surface. The time of application will also solve the problem of residues, because the chemical will not be taken up by the plant during this time of application. ✤

59FEB/MARCH 2020 | CRI TECHNOLOGY

CITRUS FCM MANAGEMENT SYSTEM

Update for 2020

For more information on the FMS: Elma [email protected]. | PhytClean questions: [email protected].

The Citrus FCM Management System (FMS) for export of citrus (excluding lemons) to the EU has now been applied for two years. Although the FMS has been scientifically proven to be an effective alternative to a stand-

alone postharvest cold treatment, intercep-tions of live FCM larvae were reported by the EU in 2018 and 2019. This highlights a critical need to implement the FMS more effectively.

In October 2019 representatives from all stakeholder groups in the citrus industry ana-lysed and deliberated where improvements to the FMS should be introduced to ensure it is implemented better. These proposed changes were shared with the Department of Agricul-ture, Land Reform and Rural Development (DALRRD). After consideration, amendments to the FMS applicable for 2020 were then formally communicated to the industry at the annual Citrus Export Coordinating Meeting held in Nelspruit on 13 November 2019. At that time DALRRD issued a strong warning to the industry to urgently ensure full and effective implementation of the FMS to avoid serious consequences in the future.

In that light, and as the 2020 citrus season gets underway, it is prudent to again point out to the citrus industry some key areas of the revised FMS. All stakeholders are strongly advised to ensure they have a full understand-ing of the entire FMS and to be aware of communication relating to the implementation for 2020, such as Cutting Edge 284 and the requirement for compulsory training. CRI is preparing training material in collaboration with the Citrus Academy, which should be available to the industry early in 2020. However, growers and packhouses may use other credible training material if they so choose.

PAUL HARDMAN, VAUGHAN HATTINGH, ELMA CARSTENS2, SEAN MOORE2 AND PAUL CRONJÉ2

1Citrus Growers Association of Southern Africa | 2 Citrus Research

The following key changes to the FMS apply and stakeholders should be aware of them and the implications for their operations:

• Orchard Sanitation: Better orchard sanitation is required with the FMS becoming more prescriptive in terms of how orchard sanitation is undertaken.

• Pre-harvest fruit infestation monitoring: Key personnel need to be trained (i.e. be able to demonstrate proper training) to ensure effective fruit infestation monitoring is implemented, including how to set up monitoring points within the orchards.

• Packhouse verification: Only packhouses that have applied and been verified by DALRRD may export citrus to the EU.

• Packhouse staff training: Compulsory training for key packhouse staff is now an aspect of registration for the EU market.

• Shipment temperature monitoring: Exporters are required to share temperature mon-itoring data to ensure the prerequisite time-temperature parameters are being met.

• Packhouse grading: Changes to the FMS make it clear that training is required for packhouse graders, and specifications are laid down for the conditions under which grading must take place.

• PPECB oversight: Provision is made for PPECB to provide greater oversight relating to FMS activities at the packhouse.

• PhytClean Update: Enhancements to PhytClean have been introduced to allow for orchards to be placed “on-hold”, and growers and packhouse managers can also withdraw orchards that are no longer suitable for the EU market.

• Corrective actions and data analysis: Greater use of available PhytClean data will take place in 2020, specifically around monitoring FCM interceptions and how this may trigger an orchard going “on-hold”. The performance of exported product will

have a direct and immediate impact on the current status of an orchard under the FMS.

• Compliance Auditing System: Compliance monitoring will be enhanced through audits. Growers will be audited for 2019 and 2020 during farm visits.

• Automated pre-verification: The mechanism by which pre-verification is to take place at the packhouse will change in 2020 as automation is introduced via the eLOT NOTICE process. Packhouses will need to adapt to this new approach where the status of a particular pallet is also tracked.

Failure to ensure compliance with all of the above places the industry’s continued access to this critical market in serious jeopardy. All stakeholders are strongly advised to ensure they are familiar with what is required from them well before packing takes place.

60 TEGNOLOGIE CRI | FEB/MAART 2020

Extension briefs forFebruary and MarchINTEGRATED PEST MANAGEMENTMealybug S.D. MooreGrowers should be scouting for mealybug regularly, by inspect-ing underneath calyces and thereby determining percentage of fruit infested. Where mealybug is under good biocontrol, infestation should peak during December in the northern pro-duction areas and during January in the Cape production areas. If mealybug infestation does not decline during January and February, respectively, suppression with a chemical treatment is advisable on early maturing cultivars. Unfortunately, buprofezin (Applaud), which was the most effective corrective option for mealybug control, may no longer be used at this time. Therefore, the available corrective options are sulfoxaflor (Closer), fenpy-roximate (Lesson) and spirotetramat (Tivoli). These products may not have a specific corrective registration, but their withholding periods do permit late season use. Although registered, meth-omyl is not a preferred option, as it is not effective at the dose generally registered for mealybug. And methomyl is the only registered corrective option for red scale. It would therefore be wise to restrict corrective usage to red scale alone, in order not to expedite the onset of resistance. Ensure that the pre-harvest interval of any product used is complied with.

The species of mealybug present should also be determined, as it appears that the biocontrol complexes of mealybug spe-cies other than citrus mealybug, might not be as effective as that of citrus mealybug. Therefore, treatments can be applied more readily when other species are identified as the dominant species. The phytosanitary status of certain species must also be borne in mind.

Finally, a mealybug infestation can also attract a carob moth infestation. Therefore, if the fruit is to be exported to a market that is sensitive to carob moth, mealybug must be effectively controlled well before harvest.

False codling moth S.D. MooreAll growers intending to export to Europe should be fully compli-ant with the False Codling Moth Risk Management System (FMS) for Export of Citrus to the European Union, and consequently the Good Agricultural Practices (GAP) described in CRI’s Production Guidelines for the Control of FCM on Citrus. For phytosanitary reasons, FCM must be controlled throughout the season to as close to a non-detectable level as possible, using a combination

of orchard sanitation and various effective registered control measures. Weekly monitoring of fruit infestation, as described in the FMS, will provide an accurate indication of how effective the control programme has been and what level of compliance there is with the export (shipping) options described in the FMS.

The following sprayable insecticides are registered and available for use against FCM: the granulovirus products (Cryptogran, Cryptex and Gratham), Methoxyfenozide (Runner, Walker, Sprint-er, Chaser, Marksman), Delegate, Coragen, Warlock, Broadband and Eco-Bb (both entomopathogenic fungi (EPF)), ensuring com-pliance with market-specific restrictions. The granuloviruses and EPF can be used up until the day of harvesting. However, note that according to label recommendations, the EPF are not suit-able corrective options for FCM and are thus not listed as such by PhytClean. A virus application should be applied shortly after a peak in FCM activity, determined by the use of a pheromone trap. However, this may be difficult to determine late in the sea-son, when FCM levels are low and generations are overlapping.

Methoxyfenozide (Runner or Walker), Delegate and Coragen are all registered to be applied once or twice per season and all have withholding periods of 30 days or less for most markets. Warlock is recommended to be reapplied 7-10 days after the first application. Therefore, these products are suitable for a final application against FCM before harvest, which ideally should not be applied later than 3-5 weeks before harvesting begins. Such a practice is strongly recommended.

Other chemical options are triflumuron (Alsystin), teflubenzuron (Nomolt), fenpropathrin (Meothrin) and Cypermethrin. Howev-er, there are some difficulties associated with these products, such as prohibitive MRLs for certain markets, development of resistance by FCM, or secondary pest repercussions. They are therefore not preferred as options for FCM.

In addition to the insecticides, there are now four mating disrup-tion products – Isomate, Checkmate, Splat and X-Mate – and an attract and kill product, namely Last-Call FCM. However, all of these products are most effective when their use is initiated early in the season, while FCM levels are still low. If this has not been done, initiation of their use late in the season is not recommend-ed. Additionally, as the weather cools towards autumn, these pheromone-based products may become less effective due to a reduction in release rate. In such a case it may be necessary to follow up these treatments with a spray for FCM.


Bud mite T.G. GroutThe period February to May is the optimal time for bud mite sprays and fenpyroximate (Mitigate or Lesson) can be used during this period at 150 ml per 100 L water. The pre-harvest intervals for most markets are 28 days. The only exception to this is for citrus types other than mandarins going to South Korea, for which the pre-harvest interval currently remains 150 days, or no applications after the end of October. In trials with fenpyroxi-mate, this product was found to have similar effi-cacy to Acarol against bud mite. Fenpyroximate will also suppress citrus red mite when sprayed during autumn for bud mite and the Lesson prod-uct is registered against all other citrus mites as well, and most recently, also mealybug.

Fruit fly A. ManrakhanFruit flies are pests of phytosanitary concern. There is a zero tolerance of fruit fly eggs and larvae in fruit consignments for export. The fruit fly pests affecting citrus are: Ceratitis capitata (Mediterranean fruit fly or Medfly), Ceratitis rosa (Natal fly) and Bactrocera dorsalis (Oriental fruit fly). The latter is present in the provinces of Lim-popo, Mpumalanga, North West, Gauteng and KwaZulu-Natal (excluding magisterial districts of Amajuba, uMgungundlovu, uMzinyathi, uThuke-la and Zululand). Ceratitis rosa was recently split into two species: Ceratitis rosa and Ceratitis quilicii (Cape fly). Both species are present in SA. The status of citrus for C. quilicii must still be confirmed.

For export of citrus to EU, growers must imple-ment the Citrus Fruit Fly Management System (Citrus FFMS), which consists of two Fruit Fly Systems Approaches (FF SA): one for lemons and limes (FF-SAL), and one for other citrus types (FF-SAO). For both FF-SAL and FF-SAO, Phytclean registration is as prescribed by the False Codling Moth Management System (FMS). In FF-SAL, there are two independent measures

that mitigate the risk of fruit flies: (1) non-host status of commercial export grade lemons and limes for fruit fly pests of citrus and (2) PPECB phytosanitary inspections of fruit packed for export. In FF-SAO, there are three independent measures that mitigate the risk of fruit flies: (1) Fruit Fly Good Agricultural Practices (FF GAP) with Packhouse Delivery Inspections as the end point, (2) packhouse grading and PPECB phyto-sanitary inspections of fruit packed for export and (3) postharvest shipping conditions as deter-mined by FMS.

FF GAP consists of two components: mo-nitoring and pre-harvest control. Monitoring of Medfly and Natal fly should be carried out using Capilure and Questlure baited Sensus traps. Monitoring of Oriental fruit fly should be conducted using bucket type traps such as Chempac Bucket trap, McPhail type trap and Lynfield trap baited with Methyl Eugenol (ME). Thresholds exist for the Sensus trapping systems and the ME trapping systems and these should be adhered to, particularly when fruit are susceptible to attack (at and after colour break). For Medfly, the threshold in a Capilure baited trap is four males per week. For Natal fly, the threshold in a Capilure baited trap is two males per week. When using Questlure in a Sensus trap, the threshold is one female fly per trap per week for all fruit fly pests of citrus. For the Ori-ental fruit fly, the threshold in a methyl eugenol baited trap set by Department of Agriculture Land Reform and Rural Development (DALRRD) is three flies per trap per week. There are other registered monitoring systems for fruit fly pests of citrus: (1) The Biolure fruit fly containing am-monium acetate, trimethylamine hydrochloride and putrescine in Chempac Bucket trap AND (2) The Chempac FF lure (Trimedlure) in Chempac Delta trap. There are, however no thresholds with the Biolure and Chempac FF lure trapping systems. Monitoring of Oriental fruit fly per Production Unit Code (PUC) is a requirement for

J.J. BESTER

W. MOMMSEN

M.C. PRETORIUS


phytosanitary registration of citrus, deciduous and subtropical fruit for export to the special markets (USA, Japan, South Korea, China and the European Union - EU). Each PUC should have at least one ME baited trap for monitoring of Oriental fruit fly. Monitoring of Oriental fruit fly should be carried out throughout the year. Trapping guidelines for surveillance of Oriental fruit fly in fruit production areas should be followed. Guidelines are avail-able at http://www.daff.gov.za under Plant Health/Exporting from SA/Phytosanitary registrations for special export markets or at http://www.citrusres.com/downloads/market-access. Trap details and trap servicing should be recorded as per trapping guidelines. All trapping results should be supplied to Early Warn-ing Systems (e-mail: [email protected]) at the end of each export season. The recommended densities for registered fruit fly trapping systems are provided in the fruit fly chapter of the Integrated pest and disease management volume of the citrus production guidelines (http://www.citrusres.com/downloads/production-guidelines). All fruit fly traps must be checked weekly

and trapping records should be documented. Lures and insecti-

cides inside traps must be replaced every 6-8 weeks. Detection

of suspect Oriental fruit fly specimens in areas considered free of

this pest should be reported immediately to the relevant surveil-

lance co-ordinator (Citrus - Aruna Manrakhan: 013 759 8000) or

to DAFF (Jan Hendrik Venter: 012 319 6384).

Fruit fly control should be initiated in middle to late summer

(either January or February, depending on regions). However, for

farms either with mixed fruit crops (such as mangoes or deciduous

fruit) or near fruit types prone to high fruit fly infestation, fruit fly

control should be implemented by December. Fruit fly baiting and

good orchard sanitation form the core of fruit fly control practic-

es. For fruit fly baiting, the use of either one or a combination of

the following registered methods is recommended: bait sprays

(either mixture of protein hydrolysate and malathion/trichlorfon

or mixture of HymLure and cyantraniliprole or GF-120 or FF 240),

M3 fruit fly bait station, Magnet MED and Cera Trap. For the use

of malathion in bait sprays, the pre-harvest interval is seven days

for citrus to all markets (including EU) except Canada (14 days),

Switzerland (28 days) and Korea (grapefruit and lemon - 28 days).

The pre-harvest interval when using either GF-120 (spinosad) or FF

240 (spinosad) is one day for all markets. The pre-harvest interval

with cyantraniliprole (ExirelTM 100SE) is one day for all markets,

except for Taiwan. When using either bait stations such as M3 fruit

fly bait station and Magnet MED, or mass trapping such as Cera

Trap, there is no pre-harvest interval. Precautions must be taken

when using bait sprays on specific citrus cultivars when fruit is at

certain maturity stages. Ground-based spray application of GF-120

should be avoided on Nadorcott at the green and colour break

stages, due to possible phytotoxicity on fruit. Ground-based spray

application of GF-120 is, however safe to use when Nadorcott fruit

is at the fully coloured ripe stage. In areas affected by the Oriental

fruit fly, the Male Annihilation Technique (MAT) must be used. A

number of male annihilation methods such as wooden fibre blocks

impregnated with ME and malathion (e.g. ready to use Invad-

er-b-Lok, Chempac ME liquid for combination with malathion 500

EC with the mixture impregnated into wooden blocks), as well as

SPLAT technology containing ME and spinosad such as STATIC

Spinosad ME have been registered for B. dorsalis control in SA. All

fruit fly control products should be applied correctly. Instructions

provided in labels of control products must be followed strictly.

Fruit fly control must always be combined with proper manage-

ment of insect pests such as FCM, which also damage mature fruit.

All records of fruit fly control practices including MAT application

need to be kept.

In all B. dorsalis infested areas, a removal permit is required

for movement of fruit outside those areas. For applications of

removal permits, either contact the relevant officials at DALRRD:

012 309 8735/8791/8763, or send an e-mail to [email protected].


GRONDGEDRAAGDE SIEKTES J. van Niekerk and M.C. PretoriusGrond en wortelmonsters behoort elke drie jaar geneem te word om sodoende die sitrusaal-wurm en Phytophthora status in sitrusboorde te bepaal. Resultate sal dien as `n bestuurshulpmid-del wat gebruik kan word om grondpatogene effektief te beheer.

Phytophthora bruinvrot/wortelvrotWeens die gevaar van fitotoksisiteit op gevoe-lige sitruskultivars tydens hoë temperature, wat gedurende Februarie/Maart kan voorkom, moet die gebruik van fosfonaatblaarbespuiting streng volgens die etiket geskied (GEEN SAGTESITRUS KULTIVARS behoort weens hul gevoelige skille gedurende hierdie tyd van die jaar met hierdie produkte gespuit te word nie). Hoë dagtempera-ture, tydelike vogstremmings en warm bergwinde kan veroorsaak dat fosfonate swart stippeltjies soortgelyk aan koperskade op vrugte veroorsaak. Bome moet daarom nie gespuit word as toestande nie optimaal is nie. ’n Wortelvrot-beheerprogram (blaarbespuiting) sal bruinvrot ook effektief kan beheer.

Bruinvrot ontwikkel slegs wanneer die klimaats-toestande gunstig is vir die patogeen (Phytoph-thora) om te infekteer en te ontwikkel. Indien dit dus ŉ droë najaar is en geen of slegs ligte reënbuie voorkom, is voorkomende fosfonaat-blaarbespuitings nie nodig nie. Indien dit egter ŉ nat najaar is kan bome met kontakmiddels soos koper of mancozeb (let op beperkings na markte) asook sistemiese produkte soos fos-fonate (let op etiket-aanbevelings vir weerhou-dingstydperk en waarskuwings), gespuit word om bruinvrot te beheer. Bo en behalwe droogte en hitte kan ŉ oormaat vogtige toestande (baie reën) ook bome onder tydelike verwelkte toe-stande plaas, wat ŉ gevaar inhou vir blaar-bespuitings. Bome moet dus nie tydens of kort na sulke toestande gespuit word nie. Laastens beïnvloed drag ook ŉ boom se gevoeligheid vir droogtespanning. Hoe hoër die drag, hoe gevoeliger is die boom vir uitdroging en hoe groter is die risiko vir fitotoksisiteit.

SitrusaalwurmWortelmonsters kan enige tyd van die jaar getrek word om die status van die sitrus-

aalwurmpopulasies in boorde te bepaal. Wyfietellings word gebruik om te bepaal of die toediening van ŉ aalwurmdoder gereg-verdig is. Die drempelwaarde voordat ŉ aalwurmdoder oorweeg word is 1000 wyfies/10 g wortels. Daar word aanbeveel dat aal-wurmdodertoedienings ’n aanvang neem tydens die begin van die reënseisoen. Dit sou daarom die regte tyd wees vir produsente in die Wes-Kaap om hulle aalwurmmonsters in Maart te trek, sodat hulle weet watter boorde om te behandel wanneer winterreëns begin. Residu-weerhoudingstydperke moet in ag geneem word. Dit is belangrik om ŉ aalwurm-beheerprogram te volg aangesien ŉ enkele aalwurmdodertoediening nie effektief genoeg is nie, en het geen noemenswaardige onder-drukking van die aalwurmpopulasies op die lange duur nie. Meermalige toedienings twee maande uit mekaar verseker dat die larwes wat uitbroei gedood word voordat hulle volwasse wyfies kan raak wat weer eiertjies kan lê.

Tydens die toediening van aalwurmdoders is dit uiters belangrik dat ten minste 40 mm besproei-ing toegedien word nadat produkte toegedien is, om te verseker dat die middels in die grond-profiel ingewas word. Die meeste aalwurmdoders loog baie stadig. Die effektiwiteit van die doders word dus belemmer, indien hulle nie behoorlik deur die wortelsone versprei word nie. Geen aalwurmdoder behoort deur drupbesproeiing-stelsels toegedien te word nie. Indien toedien-ings in boorde met druptoediening gedoen moet word, behoort die middels as ŉ bandplasing (half meter aan beide kante van die drupperlyn) oor die drupperlyn gedoen te word. Dit kan wel deur mikro-besproeiingstelsels toegedien word.

Indien dit beplan word om ŉ boord te verwyder behoort ŉ aalwurmmonster geneem te word voordat die boord verwyder word, sodat dit bepaal kan word of sitrusaalwurms teenwoordig is. Dit dien as ŉ bestuursriglyn om ’n geskikte onderstam te kies in gevalle waar ŉ herplant-strategie uitgewerk moet word.

CITRICULTURE Fruit production and qualityP.J.R. CronjéInternal quality: If properly timed, regulated deficit irrigation can result in increased total


soluble solids (TSS) and an increase, or no response in titrata-ble acidity. Deficit irrigation retards the breakdown of acid and can influence the solids:acid ratio at harvest for better or worse, depending on cultivar characteristics. It is mainly aimed at early cultivars like Satsuma, but other early maturing cultivars with low internal quality could benefit. Less water is applied, and at longer intervals. Therefore, irrigation is continued but at a reduced level. Trees should be irrigated lightly two weeks prior to harvest. No water stress should be imposed during the initial growth phase of the fruit, i.e. during and after flowering, but only during the final maturation phase, i.e. the last two months prior to harvest (January for Satsuma). Any water stress earlier than the end of January could lead to reduced fruit size and loss of rind integrity. In high rainfall areas, regulated deficit irrigation may not be successful. The deficit should be imposed slowly, so that the trees can adjust without symptoms of drought. Severe water stress can have adverse effects on tree health, fruit size and fruit quality. High nitrogen is antagonistic to the effect of deficit irri-gation. Management of this technique is much easier when trees are planted on ridges, and when the right scheduling equipment is used. Additionally, regulated deficit irrigation imposed the last two months prior to harvest also enhances the rate of colour de-velopment. Selective harvest of outside fruit and delaying harvest of inside fruit will result in a higher proportion of fruit with higher TSS and better colour.

Maturity indexing on early cultivars like Satsuma should com-mence. Maturity indexing is done to predict the rate of change in fruit maturity in order to harvest fruit at optimal maturity, to main-tain acceptable commercial shelf life. The aim is to define changes

or rate of change in acids and sugars and to build up a data base over a number of years for comparison. Random sampling of fruit every week from each of 10 representative trees should start 4-6 weeks before the expected harvest date. Titratable acidity is determined by titration with sodium hydroxide. Sugar content (Brix) is determined using a refractometer, and the sugar:acid ratio calculated and fruit colour should be read from a colour chart. All the parameters mentioned above should be plotted on a graph over time. Once plotted, trends will become apparent, harvest dates can be estimated, and problem areas in internal and external quality parameters can be identified and manipulated.

Fruit growth and size: Fruit growth during this time is important to achieve optimum size at harvest. Fruit growth is in the peak of phase II, in which the majority of fruit size increase takes place for most cultivars (Figs. 1 and 2). Ensure optimal irrigation and try to avoid stress conditions, as this might have an adverse effect on fruit size. Fruit thinning plays a critical role in fruit size (see Cutting Edge no. 32: Fruit size improvement). Correct pruning practices are the most effective way to manipulate the number of fruit per canopy volume and the eventual fruit size. For more information, refer to SA Fruit Journal Oct/Nov 2015: The reproductive phenol-ogy of Citrus III: Morphogenesis from flower to fruit.

Regrowth control should be done, especially after heavy pruning earlier in the season. A lot of regrowth adversely affects fruit size and is antagonistic to fruit colour development, especially for early maturing cultivars.

Oleocellosis: Late summer vegetative growth of bearing trees should be kept to a minimum as excessive vegetative vigour duringthis period is associated with high incidence of oleo at harvest.

Figure 1. Historical fruit

growth rates (mm per day)

of different citrus

cultivars in the Western

Cape region


Rind colour development: Late nitrogen appli-cation and the use of heavy summer oil sprays should be avoided, as these treatments are antagonistic to rind colour development.

GEÏNTEGREERDE BEMESTING/INTEGRATED FERTILISATION P. RaathNeem van blaar- en grondmonstersDie periode van Februarie tot Junie moet ge-bruik word vir jaarlikse blaar- en grondontle-dings. Blaarmonsters behoort jaarliks geneem te word, terwyl grond elke drie jaar gemonster kan word. Omdat die waarde van die ontleding ge-heel en al afhang van die mate wat die monster die blok se voedingstatus verteenwoordig, moet baie moeite gedoen word met die monster-nemingsproses. Standaardiseer die monster-nemingsprosedure. Monsterblare elke jaar: 1) Rondom dieselfde datum - pluk blaarmonsters elke jaar vir elke spesifieke blok gedurende ’n bepaalde week vanaf Februarie tot einde April.

2) Vanaf dieselfde groep bome (sogenaamde “indeksbome”) - verdeel boorde in monster-nemingseenhede wat nie groter as 5 ha is nie - kies dan drie tot vier indeksrye wat verteenwoor-digend van die hele eenheid is - merk die rye

en gebruik elke jaar dieselfde rye vir monsterne-ming. Swak of geil kolle moet egter afsonderlik gemonster en gemerk word.

3) Op dieselfde posisie in die bome - slegs blare agter ’n vrug, wat in die lente op dieselfde takkie as die vrug ontwikkel het, word gemon-ster - d.w.s. blare wat tussen vyf en agt maande oud is (Figuur 3) – monsterblare tussen heup- en skouerhoogte.

Pluk tussen 50 en 70 blare, plaas dit in ’n skoon plastieksakkie, druk die lug uit en knoop die sakkie toe. Merk die monster deeglik – moet nie direk op die sakkie skryf nie, aangesien selfs permanente ink geneig is om af te kom.

Sample soil at least every three years:

1) When fertilisation has stopped or application rates are low - e.g. late summer to autumn (Feb-ruary to June).

2) From the same position (e.g. the index trees): use the same three to four index rows that are used for leaf sampling – they must be represent-ative of the whole unit. Take samples according to the fertiliser application pattern/wetted zone – micro-irrigated blocks must be sampled under the tree canopy, while drip-irrigated blocks are sampled either between the dripper and the perimeter of the wetted zone. Or if the wetted zones of adjacent drippers overlap, take it

Figure 2. Historical fruit

growth rates (mm per day)

of different citrus cultivars

in Limpopo

Pumeloes


halfway between two drippers. Ten to 15 sub-samples must be taken and mixed in a bucket, from which a 500 g representative sample is then sent to the laboratory. Poor or vigorous areas must be sampled separately.

3) At the same depth: remove organic debris from the soil’s sur-face and take the sample from the top to 30 cm depth. If occur-rence of soil acidity or salinity is suspected, an additional sample must also be taken from the 30-60 cm layer.

Use either an auger or spade to take the samples over the full top 30 cm. Put the sample in a plastic bag that can be thoroughly sealed and mark it properly (do not write directly on the plastic bag).

Interpretation of leaf analysesLeaf analyses are an indicator of the nutritional status of the trees. There is an established relationship between the concentration of the nutrient elements in the leaves and tree performance. The goal should be to achieve a plant nutrient status that falls within the optimal range for each nutrient.

Interpretasie van grondmonstersGrondontledings verskaf inligting wat help om te besluit watter stappe geneem kan word om tekorte, wanbalanse en oormate in die voedingstatus van die bome reg te stel. Ongelukkig word in-terpretasie van die chemiese resultate dikwels gekompliseer deur die verskeidenheid ekstraksie-metodes en maniere waarop resul-tate uitgedruk word. Interpretasie van grondontledings moet dus met inbegrip van die ekstraksie-metodes gedoen word.

POST HARVEST PATHOLOGY – PRE-PACKING POINTERS C. Savage, W. du Plooy & K.H. LesarOrchard sanitation: Just before the picking season starts, san-itation is of crucial importance. For reducing fungal spore load,

as well as keeping FCM and fruit fly under control, remove all fallen and decayed fruit (including in the trees) from the orchard. Bury or macerate fruit and allow to dry in the sun away from the orchards and packhouses.

Skirt trees for sour rot and brown rot control: Ensure that trees are adequately skirted, preventing low hanging fruit, especially in heavily laden trees, thereby reducing the risk of Phytophtho-ra brown rot infection during the rainfall season. Remove dead wood from all citrus trees to reduce the spore load of the latent citrus pathogens.

Prevent injuries: Ensure that picking teams are trained to focus on the prevention of injuries. Avoid snap picking, unless pickers have mastered the technique. Injuries are the number one cause of postharvest decay.

Packhouse sanitation: Before any fruit is brought to the pack-house in the 2020 season, the entire building and line need to be thoroughly cleaned. Use an appropriate sanitiser to clean everywhere from the roof to the floor. Include walls and hard to reach nooks and crannies.

• Never allow any fruit, and more importantly, any fungi-cide-treated fruit, to lie around in the packhouse.

• Spray the packhouse with sanitisers regularly and immediately after finding a single rotten fruit.

• Constantly monitor concentrations of sanitisers in dump tanks, sprays, rinses, etc. Ensure that these sanitisers are being used according to the correct specifications (e.g. pH).

• Wash trailers/harvesting bins with a suitable sanitiser before they leave for the orchard.

• Ensure that packed cartons are cooled as soon as possible to prevent decay development.

• Store retention samples for each consignment and check them regularly for waste and other developing factors.

Selection of fungicides: In many packhouses the chemicals that will be used during the 2020 season are being sourced and ne-gotiated. Decide on a chemical program for the coming season that is in line with decay control and export market regulations. Make use of the CRI Postharvest Factsheets that are provided at the Postharvest Workshops during January and February every year. If using a new product, ensure that it is safe to do so (possible phytotoxixity; MRL restrictions) and that it is applied correctly.

In light of the increased cold-temperature shipping and FMS protocols, it is important that packhouses use thiabendazole (TBZ) for all fruit being exported. TBZ applied in the wax pro-vides protection against chilling injury and is also very important to help control latent pathogen infections. ✤

Figuur 3. Voorstelling van die posisie van die blare wat vir

blaarontleding geneem moet word | Figure 3. Illustration of

the position of the leaves that must be sampled for analysis


The effect of non-permanent netting on mandarin fruitOCKERT P.J. STANDER1, J. NORTH1, J.M. VAN NIEKERK2,3, T. VAN WYK3, C. LOVE4, AND M.J. GILBERT4

In Citrus spp., non-permanent netting (NPN) is used during a particular stage in the sea-son to protect trees and fruit from damage that could be caused by hail (Wachsmann

et al., 2014). It is used in some cultivars dur-ing flowering, to exclude bees, preventing cross-pollination and seed development (Gam-betta et al., 2013; Gravina et al., 2016; Otero and Rivas, 2017). However, it is unclear how the covering of trees with NPN before, during and after flowering impacts on the deposition of foliar sprays applied, insect pest prevalence and fruit production. The objectives of this study were to evaluate the effects of NPN on these aspects in the production of "Nadorcott" mandarin fruit.

Materials and methodsThe study was conducted in a commercial orchard of six-year old "Nadorcott" manda-rin trees, with "Carrizo" citrange rootstock at Citrusdal in the Western Cape province. Trees were planted at a spacing of 5.5 × 2.5 m.

The following NPN treatments were applied prior to flowering in August 2017: 1) trees covered with NPN from August 2017 to No-vember 2017 (NPN August to November.), 2) trees covered from August 2017 to March 2018 (NPN August to March), and 3) trees covered from August 2017 until harvest in July 2018 (NPN August to July). Trees were covered to the ground with a white (18% shade) AHN-55 (55 g·m-2) mesh type NPN.

Data collection:Foliar spray deposition To evaluate the effects of NPN on foliar spray deposition in the tree canopy, control and NPN treatments were sprayed in January 2018 and in June 2018 at different water volumes, with a 2 000 L oscillating Nieuwoudt spray machine. The January sprays were applied at volumes of 3 500 and 15 000 L·ha-1. The June sprays were applied at volumes of 3 500, 7000 and 15 000 L·ha-1. Each foliar spray contained fluorescent pigment allowing for visualisation of the spray deposition on the leaf and fruit surfaces. Leaves and fruit were sampled from three uniform trees within the respective treatment replicates. For the January evaluation, only leaves were sampled; whereas fruit and leaves were sampled for the June evaluation. Samples were collect-ed from different tree canopy positions: three vertical positions, viz. top, middle and bottom; and two horizontal positions, viz. inner canopy (leaves 30 to 50 cm inside the tree canopy) and outer canopy (leaves or fruit on the outside of the tree canopy). Deposition quantity was measured as the percentage of leaf or fruit area covered by pigment particles, i.e. the percent-age fluorescent particle coverage (FPC%). De-position uniformity between leaves or fruit was calculated as the uniformity in pigment deposi-tion in a batch of 12 leaves or five fruit (standard deviation × 100/mean) and referred to as CV%.

Insect pest prevalenceFalse codling moth (FCM) was monitored using a yellow Delta trap containing a sticky floor and

AcknowledgementsWe thank CP Mouton and Conrad Vorster for allowing access to their orchard at Houtkaprug in Citrusdal, and Citrus Research International (Pty) Ltd and the Department of Science and Technology (SIF-RCE) for financial support. We also express our appreciation to Drape Net SA (Pty) Ltd for providing the nets.

1Citrus Research International, Department of Horticultural Science, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa. 2Citrus Research International, Department of Plant Pathology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.3Department of Plant Pathology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.4Citrus Research International, Department of Conservation Ecology & Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.


a pheromone lure to attract males. Mediterra-nean fruit fly was monitored using a Sensus trap containing a Capilure (trimedlure) capsule and a small dichlorvos-impregnated block, to attract and kill male fruit flies. Traps were placed in the tree canopy in one control, one NPN August to March, and one NPN August to July replicate. The farm was included in the commercial area-wide Xsit Sterile Insect Release programme. Both wild and sterile FCM males were therefore monitored by traps.

Leaf mineral nutrient concentration Leaves were sampled according to the South African citrus industry standard (Du Plessis 1977; Du Plessis et al., 1992; Du Plessis and Koen, 1992). Mineral nutrient analyses in leaf samples were conducted by an accredited commercial analytical laboratory. The concentrations of the mineral nutrients in the leaf were expressed as mg·g-1 leaf dry weight (DW) for macronutrients, or mg·kg-1 leaf DW for micronutrients.

Fruit yield Commercial fruit harvest commenced at the end of July 2018 and was completed by end August. To determine the total fruit yield of the respec-tive treatments, fruit from two trees within each treatment replicate row were harvested and total fruit yield was determined for each replicate in kg fruit per tree. A sample of 150 fruit from each treatment was measured using an electronic calliper. This allowed determination of the aver-age fruit weight and fruit size distribution from each treatment.

Fruit qualityFruit quality attributes, i.e. fruit size (diameter), total soluble solids (Brix°), titratable acidity (TA), and fruit juice content (%), were determined from 36 fruit within each treatment.

Fruit surface damage Fruit surface damage evaluations were done at the time of commercial harvest in July 2018, on the same fruit that was used for fruit quality eval-uations. All the fruit was examined for sunburn damage, light or severe wind damage, and any evidence of pest damage or chemical burn.

Statistical analysis All collected data were statistically analysed, using appropriate statistical methods.

ResultsFoliar spray depositionFor the January foliar spray deposition analysis, greater FPC% was observed on control leaves compared with the NPN treatment (8.8 and 6.1 FPC%, respectively), regardless of foliar spray volume (Table 1). Similarly, foliar spray volume had no influence on CV%, although it was significantly better on leaves in control trees, compared to trees covered with NPN (64.9 and 75.2 CV%, respectively) (Table 1).

The NPN treatment effect results on leaves in June showed that, irrespective of the foliar spray volume, significantly more fluorescent pigment was deposited on leaves of control trees com-pared to leaves of NPN trees (4.8 and 3.1 FPC%, respectively) (Table 2). Comparison of the CV% in trees from the different NPN (covered vs. open) treatments showed that CV% on leaves of control trees was better compared to leaves of NPN trees (59.6 vs. 80.5 CV%), irrespective of foliar spray volume (Table 2).

Table 1. Effects of non-permanent netting

(NPN) on deposition quantity (FPC%) and depo-

sition uniformity (CV%) of foliar sprays on leaves

of "Nadorcott" mandarin trees in January 2018

Treatments FPC% CV%

Control 8.8az 64.9b

NPN 6.1b 75.2a

P value 0.0055 0.0062

z Different letters in the same column denote significant differences between values at the 95% confidence level

Table 2. Effects of non-permanent netting

(NPN) on deposition quantity (FPC%) and depo-

sition uniformity (CV%) of foliar sprays on the

leaves of "Nadorcott" mandarin in June 2018

Treatments FPC% CV%

Control 4.8az 59.6a

NPN 3.1b 80.5b

P value 0.0035 0.0014



The results obtained from fruit collected in June indicated that the 15 000 L.ha-1 foliar spray volume resulted in the best FPC% on fruit at both horizontal canopy positions (inside = 16.9 FPC% vs. outside = 17.9 FPC%), irrespec-tive of NPN treatment (covered or open) (Table 3). The 7 500 L.ha-1 foliar spray volume resulted in an FPC% of 15.26 on fruit on the outside of the tree canopy, which was similar to the FPC% on fruit for the 15 000 L.ha-1 foliar spray volume. However, on fruit on the inside of the tree canopy, the 7 500 L.ha-1 foliar spray volume resulted in significantly poorer FPC% (10.14). The poorest FPC% on fruit resulted from the 3 500 L.ha-1 foliar spray volume (in-side = 9.3 FPC% and outside = 6.9 FPC%) (Table 3). The FPC% in the 3 500 L.ha-1 foliar spray volume was similar on fruit in the control (8.8 FPC%) and NPN treatments (7.4 FPC%) (Table 3). For the 7 500 L.ha-1 foliar spray volume, the FPC% values on fruit differed significantly between the control and NPN treatments. On the fruit from control trees, the FPC% was 19.3 and 6.1 on fruit from NPN treat-ments (Table 3). At the 15 000 L.ha-1 foliar spray volume the FPC% on fruit was similar for NPN and control trees (15.3 vs. 19.5 FPC%). Results from the spray volume and NPN treatment interaction showed that the 15 000 L.ha-1 foliar spray volume resulted in similar CV% on fruit from NPN and control trees (43.1 and 44.3 CV%) (Table 3). On fruit from control trees, the 7 500 L.ha-1 foliar spray volume resulted in similar CV % compared to that obtained for the 15 000 L.ha-1 foliar spray volume. However, in the NPN treatment, the 7 500 L.ha-1 foliar spray volume re-sulted in the poorest (70.3 CV%) (Table 3). The 3500 L.ha-1 foliar spray volume performed similarly to the 15 000 L.ha-1 foliar spray volume in terms of CV%, for both NPN and control treatments (47.8 and 40.9 CV%) (Table 3).

Insect pest prevalence

Fig. 1. The average number of a) released (sterile), male false cod-

ling moth (FCM) (Thaumatotibia leucotreta), b) wild, male FCM, and

c) fruit flies (Ceratitis capitata) catches per trap per week for control

and non-permanent netting (NPN) treatments from December 2017

to July 2018

Table 3. Mean deposition quantity (FPC%) and deposi-

tion uniformity (CV%) values for the significant foliar spray

water volume × treatment interaction on the fruit from

non-permanent netting (NPN), or control trees sprayed at

either 15 000, 7 500 or 3 500 L·ha-1 in June 2018

Foliar spray water Treatments FPC% CV% volume (L·ha-1) 15 000 Control 19.5az 44.3b NPN 15.3a 43.1b

7 500 Control 19.3a 50.9b NPN 6.1b 70.3a

3 500 Control 8.8b 40.9b NPN 7.4b 47.8b

P value 0.0262 0.0484

z Different letters in the same column denote significant differences between values at the 95% confidence level.

The average number of weekly sterile FCM male catches in the control traps relative to the NPN treatments, was considerably high (Fig. 1A). A few sterile moths were caught in traps that were under the NPN (Fig. 1A). Trap catches of wild FCM were very low for the duration of the experiment. No wild FCM males were caught in the NPN treatments during the times when the netting was in place (Fig 1B). Wild FCM males were only caught in the control treatment and in one of the NPN treatments after the netting had been removed. Regarding fruit flies, the same pattern was repeated as for FCM with catches greatly reduced beneath the NPN (Fig. 1C).


Table 4. Effects of non-permanent netting (NPN) on leaf mineral nutrient

concentration in March 2018

Treatments (n=8) Leaf macronutrients concentration (mg·g-1 leaf DW)

N P K Ca Mg

Control 31.1 2.0 12.3 37.1 3.1

NPN 32.9 1.9 12.9 38.1 3.3

P value 0.0516 0.7873 0.6653 0.7413 0.6545

Leaf micronutrients concentration (mg·kg-1 leaf DW)

Na Mn Zn Fe Cu B

Control 387 132 40az 277a 3.5 60

NPN 401 107 22b 156b 3.5 73

P value 0.7884 0.3623 0.0317 0.0041 1.0000 0.2109


Table 5. Effects of different non-permanent netting

(NPN) treatments on fruit yield of "Nadorcott" mandarin

Treatments (n=8) Fruit yield

kg per tree No per tree

Control 95az 1112a

NPN August to November 72b 782b

PN August to March 69b 765b

NPN August to July 102a 1157a

P value 0.0008 0.0002


Fruit surface damageAcross all treatments, light wind damage was most common (42%), followed by undamaged or clean fruit (36%), and fruit showing severe wind damage (19%) (Fig. 3). When comparing the wind damage on fruit from inside the canopy, the percentage of light wind damage was greater for fruit from the control treatment compared to NPN treatments (Fig. 3). Inner canopy fruit in the NPN August to November treatment had the highest percentage of clean fruit and the lowest percentage of light wind damage, but also had the greatest percent-age of severe wind damaged fruit (Fig. 3A). For the outer canopy fruit, the amount of fruit suffer-ing wind damage, particularly in the severe wind damage category, was significantly greater than that of the inner canopy. The NPN August to July treatment showed an equal percentage of clean fruit to the NPN Aug. to Mar. treatment, but the percentage of severe wind damage was lower (Fig. 3B). The NPN August to November (22%) and the NPN August to March (21%) treatments resulted in similar fruit sunburn damage, compared to the control (27%) (Fig. 4). The longer NPN treat-ment (NPN August to July) resulted in significantly lower percentage of sunburned fruit compared to the control (9 vs. 27), but a similar percentage of sunburned fruit compared to the NPN Aug. to Mar. treatment (Fig. 4).

ConclusionIn general, the use of NPN in the production of "Nadorcott" mandarin reduced foliar spray deposi-tion on leaves and fruit, resulting in lower concen-trations of certain micronutrients in leaves. In trees where NPN was removed before July, yield was

Leaf mineral nutrient concentrationsThere were no differences between the concent-rations of any of the macronutrients N, phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg) in leaves of the control and the NPN treatment in March (Table 4). For micronutrients, the concentra-tions of zinc (Zn) and iron (Fe) were significantly greater (by 81 and 78%, respectively) in leaves of the control treatment compared with leaves of the NPN treatment (Table 4).

Fruit yieldIn the NPN August to November and NPN August to March treatments, fruit yield (kg fruit per tree) and number of fruit per tree were significantly lower compared to the control and the NPN August to July treatments (Table 5). The NPN August to March treat-ment resulted in the lowest fruit yield (69 kg and 765 fruit per tree), but it did not differ significantly from fruit yield of the NPN August to November treatment (72 kg and 782 fruit per tree) (Table 5). The NPN August to July treatment resulted in the greatest fruit yield (102 kg and 1157 fruit per tree), but it did not differ significantly from fruit yield of the control (95 kg and 1112 fruit per tree) (Table 5). Fruit of the NPN treatments consisted of a greater amount of larger sized fruit (SC1 to SC1XX), whereas fruit in the control consisted of more smaller sized fruit (SC4 to SC 5) (Fig. 2).

Fruit quality

The NPN treatments had no significant effect on fruit rind colour, juice content and juice Brix°, compared to the control.


Literature citedDu Plessis, s.F. 1977. Soil analysis as a necessary complement to leaf analysis for fertilizer advisory purposes. Proc. Intl. Soc. Citricult. 1:15–19.

Du Plessis, s.F. AnD t.J. Koen. 1992. Leaf analysis norms for lemons [Citrus limon (L.) Burm.]. Proc. Intl. Soc. Citricult. 2:551-552.

Du Plessis, s.F., t.J. Koen, AnD W.J. oDenDAAl. 1992. Interpretation of Valencia leaf analysis by means of the N/K ratio approach. Proc. Intl. Soc. Citricult. 2:553-555.

GAmBettA, G., A. GrAVinA, c. FAsiolo, c. Fornero, s. GAliGer, c. inzAurrAlDe, AnD F. rey. 2013. Self-incompatibility, parthenocarpy and reduction of seed presence in ‘Afourer’ mandarin. Scientia Hortic. 164:183–188.

GrAVinA, A., G. GAmBettA, F. rey, AnD n. GuimArAes. 2016. Mejora de la product-ividad en mandarina ‘Afourer’ en aislamiento de polinizacion cruzada. Agrociencia Uruguay. 20:22–28.

otero, A. AnD F. riVAs. 2017. Field spatial pattern of seedy fruit and techniques to improve yield on ‘Afourer’ mandarin. Scientia Hort. 225:264–270.

WAchsmAnn, y., n. zur, y. shAhAK, K. rAtner, y. Giler, l. schlizermAn, A. sADKA, s. cohen, V. GArBinshiKoF, B. GilADi, AnD m. FAintzAK. 2014. Photoselective anti-hail netting for improved citrus productivity and quality. Acta Hortic. 1015:169-176.

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Fig. 2. Effects of different non-permanent netting (NPN) treat-

ments on the distribution of different commercial fruit size calibres

(SC) in the yield of "Nadorcott" mandarin

Fig. 4. Effects of different non-permanent netting (NPN)

treatments on sunburn of "Nadorcott" mandarin fruit

Fig. 3. Wind damage of fruit from all treatments a) inside and

a) outside tree canopies of control and non-permanent netting

(NPN) treatments at time of commercial harvest in July 2018

reduced by up to 37%, but a longer NPN treatment resulted in similar fruit yield compared to the control. The lower fruit yield in short NPN treatments was probably caused by fruit drop exacerbated by the physical removal of NPN. The use of NPN had no effect on commercial fruit quality attributes and where the NPN treatment was applied until fruit harvest, sun-burn damage of fruit was reduced by 17%; outer canopy fruit suffered increased wind damage or scarring. Citrus growers in very windy areas should, therefore bear this in mind if consid-ering making use of NPN. ✤

Commercial fruit size calibre

Commercial fruit size calibre

Frui

t per

tree

(%)

Sunb

urne

d fru

it (%

)

Treatments


IRRIGATION OF CITRUS TREESA practical approach

To secure high yields of good quality fruit, producers sometimes think it is necessary to adjust their irrigation practices in accordance with the availability of water. Although significant changes in irrigation practices

might be required in desperate water-limiting situations, accurate irrigation scheduling usually leads to less water being used than is available, even in low rainfall seasons. This is achieved by pursuing some age-old principles to establish when, and how much, one must irrigate. In this paper, we explain the approach to generate accurate irrigation schedules for individual orchards. New research data were incorporated for more accuracy in the calculations.

Tree water requirements can be estimated (i) from soil water measurements, (ii) by studying tree reaction/performance or (iii) by measuring climatic variables. Last mentioned is the simplest and most commonly used method to schedule orchard irrigation.

Irrigation terminology and concepts explainedIt is helpful to understand some important concepts to schedule orchard irrigation accurately.

1. Water holding capacity: This is the amount of plant available water (PAW) that a given soil can hold within the plant’s root zone, e.g. water that is accessible to the trees. It is expressed

as millimetre per meter soil (mm/m) and can be determined in a soil laboratory where the difference between field capacity water content and wilting water content is measured by applying a specific amount of pressure to wet soil. The readily PAW, for example, is the water held by the soil between -10 kPa and -100 kPa. Soil texture class can also be used to estimate it, with Table 1 as guideline.

2. Allowable depletion: This is the maximum amount of readily PAW allowed to be depleted from the soil profile by tree water use (expressed as a percentage of the readily PAW in Table 1) before the next irrigation. Allowable depletion is usually 40% or

PIETER RAATH (CRI), CHRIS MALAN (Netafim) & TEUNIS VAHRMEIJER (Villa Crop) (Photos page 78)

Table 1. Estimated readily plant available water (PAW) of soils

with different textures (Myburgh, 1993)

Texture class Water holding capacity (mm/m)

Very coarse sand 50

Coarse sand, fine sand, loamy sand 80

Sandy loam, fine sandy loam 125

Very fine sand, loam, silty loam 160

Clayey loam, silty clayey loam, sandy clayey loam 180

Sandy clay, silty clay, clay 170

Effective and accurate irrigation of citrus trees has become critical due to rising electricity costs and an unreliable supply of fresh water.


Figure 1: (Opposite) Availability of irrigation water for citrus production is at increasing risk of becoming insufficient

to sustain the rate of expansion of the industry

Figure 2 (Above): Drip irrigation is becoming more popular due to more efficient use of water since evaporation

from the soil surface is less

less for citrus trees; for sandy soils, however, this should be reduced to 30% of readily PAW.

Due to citrus trees’ susceptibility to Phyto-phthora, and the growing pressure on fresh-water resources, there is a need to increase the water use efficiency (e.g. less water used per kilogram fruit produced) of citrus. This can be done by increasing the allowable deple-tion of readily PAW during each phenological stage to the maximum without affecting fruit quality or tree performance (Table 2).

During periods of severe water shortages, controlled stress can be applied from May onwards with little effect on yield and fruit quality. By allowing 50% depletion of readily PAW during this period, irrigation intervals will be longer, resulting in less water being used.

3. Total tree water use or ET (evaporation and transpiration) is the term used to describe water use by the trees. Transpiration (T) refers to the water that moves through the tree/plant and is lost to the atmosphere by evapora-tion from the surface of the leaves and other

Table 2. Maximum depletion of readily plant available water (PAW) allowed with-

out having an impact on fruit quality (adapted from Falivene et al., 2006)

Phenological stage

Flower bud induction and initiation

(Apr-May)

Flowering & fruit set(Sep-Oct)

Stage 1 of fruit growth: cell division

(Oct-Nov)

Stage 2 of fruit growth: cell expansion

(Nov-April)

Stage 3: Fruit maturation

(May onwards)

Max. % depletion of readily PAW

40%

30%

30%

40%

40%-50%

Comments

Flowering can be increased by short periods of moderate drought.

Any water stress will impact on fruit set and cause an excessive drop of fruitlets - especially in navels.

An important stage to ensure fruit size since the number of cells in the fruit are determined - this

directly affects fruit size. Any impact on cell division has an irreversible effect on fruit size.

This is the period of maximum growth due to cell enlargement. Any form of stress causes

the fruit to stop growing, but the effect is reversible.

This is the fruit maturation phase during which the rate of fruit growth levels off. Any further fruit

growth can still be reduced due to stress. It however is reversible, and if excessive stress is avoided, a higher extraction of PAW will not affect fruit size.


Region in South Africa Month

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun

Messina 2.2 2.8 3.6 4.1 4.6 4.8 4.8 4.5 4.2 3.3 2.5 2.0

Letsitele 2.0 2.5 3.2 3.8 4.0 4.2 4.3 4.1 3.6 2.9 2.3 1.9

Nelspruit 2.6 3.3 4.1 4.3 4.5 4.7 4.9 4.7 4.0 3.3 2.9 2.5

Marble Hall 1.9 2.6 3.5 4.1 4.5 4.7 4.9 4.6 3.9 3.0 2.2 1.8

Rustenburg 2.0 2.7 3.7 4.3 4.7 4.9 4.9 4.6 3.9 3.0 2.4 1.9

Addo 2.3 3.9 3.7 4.5 5.2 5.7 5.7 5.1 4.2 3.2 2.5 2.2

Patensie 2.3 2.7 3.5 4.2 4.8 5.4 5.5 4.9 3.9 3.1 2.4 2.1

Robertson 1.6 2.2 2.6 3.5 4.5 4.7 5.3 5.1 3.7 2.7 1.7 1.8

Citrusdal 1.4 2.2 3.1 4.6 5.9 6.6 7.0 6.3 4.9 3.1 1.8 1.3

Kakamas 3.2 4.2 5.5 7.1 8.5 9.4 9.5 8.3 6.7 5.0 3.6 2.8

Table 3. Long-term monthly reference evapotranspiration (ETo) values (mm/day), generated from SAPWAT,

for different citrus producing regions

aerial parts of the plant. The amount of water transpired is determined by light intensity, leaf canopy, wind, temperature and relative humid-ity. If the water applied is not a limiting factor, the type of irrigation system does not influence the transpiration rate of crops.

Evaporation (E) happens when a liquid turns into gas and is removed from the evaporating surface. As trees grow, the ratio between T and E from the soil surface (Es) changes. The amount of water lost through Es is determined by the size of the wetted soil surface area, irrigation in-tensity (how often the soil surface is wetted), soil type, mulching practices and energy available to evaporate the water from the soil surface. Water that is lost to the atmosphere through evapora-tion during the application process, e.g. water released from the micro-sprayer or drip emitter that does not reach the soil, is discussed later since it forms part of the application efficiency of an irrigation system.

Automatic weather stations provide accurate information with regard to radiation, relative humidity, temperature and wind speed. These measured weather elements are used in the modified Penman Monteith equation to calcu-late the reference evapotranspiration (ETo). Last mentioned gives an indication of the intensity of the present climatic conditions (atmospheric de-mand) and is used to calculate total tree water use (ET). Often long-term ETo values, as indicat-ed in Table 3, are used for planning

purposes, such as calculation of the annual water budget for each orchard, water avail-ability for expansion, or for irrigation scheduling (calendar method). These, however, do not take seasonal weather patterns (like sudden heat waves or unexpected rain) into consideration.

4. Crop coefficient (Kc): There is a direct relation-ship between ETo for a specified period and the amount of water an orchard needs during the same period. This relationship is described by the Kc. Crop coefficient values also account for tree characteristics, such as canopy size, plant density and effective canopy cover (fc eff) and will change according to the season and as the phenological stage of the trees progresses. Typical Kc values for citrus trees in the main climatic regions of production in SA are listed in Tables 4 and 5. These values were adapted from transpiration coefficients (Kt), determined by Vahrmeijer & Tay-lor (2019) for trees of different ages and canopy sizes, and also incorporate Es in micro-irrigated and drip irrigated orchards, respectively.

The impact of canopy cover is evident – from there the suggestion that trees should be heavily pruned under conditions of restricted water availability. These trees usually recover faster than water-stressed trees without any canopy reduc-tion.

5. Application efficiency: This is the percent-age of the irrigation water that reaches the soil and roots after it is released from the irrigation system, i.e. that actually replaces the volume of


Table 4. Crop coefficients (Kc) for citrus trees under micro-irrigation (adapted from Vahrmeijer & Taylor (2019)

Canopy Month cover


a70% 1.82 1.50 1.22 1.06 0.97 0.93 0.93 0.95 1.10 1.35 1.54 1.71

b50% 0.80 0.70 0.63 0.57 0.51 0.46 0.48 0.48 0.49 0.68 0.87 0.95

c30% 0.38 0.36 0.38 0.32 0.27 0.29 0.29 0.30 0.30 0.32 0.40 0.40

Table 5. Crop coefficients (Kc) for citrus trees under drip-irrigation (adapted from Vahrmeijer & Taylor (2019)

Canopy Month cover


a70% 1.10 0.91 0.74 0.64 0.59 0.56 0.56 0.58 0.67 0.82 0.93 1.04

b50% 0.48 0.43 0.38 0.35 0.31 0.28 0.29 0.29 0.30 0.41 0.53 0.58

c30% 0.23 0.22 0.23 0.20 0.16 0.17 0.17 0.18 0.18 0.20 0.24 0.24

aTypical of mature trees >15 years old | bTypical of mature trees 10-15 years old | cTypical of trees <10 years old

Figure 4: When a proper profile hole is made, the distribution of both the

roots and the wetting zone can be established – it also allows one to verify that

proper distribution of water by the irrigation system is obtained

Figure 3: Maintenance of drip irrigation systems is

crucial - especially in areas where water quality is

poor, clogging of drippers must to be prevented

water depleted from the root zone. A decrease in the application efficiency is mainly caused by conditions that favour evaporation and decrease infiltration of irrigation water. Consequently, it is generally accepted that drip irrigation systems are more efficient compared to other irrigation systems, because less water is lost due to evap-oration and run-off. The efficiency of the most common irrigation systems is listed in Table 6.

6. Spacing of sprinklers/drippers: This is the distance (in meters) between the sprinklers or

drippers in the irrigation line. If the spacing of the sprinklers is uneven, or where double row drip lines are used, it is more practical to use the num-ber of emitters per hectare in the calculations.

7. Delivery rate: This is the volume of water that passes through the opening of the sprinkler or dripper per time unit, at a given pressure. It is expressed in litre per hour, and should be meas-ured in the orchard because pressure variation can affect the delivery rate of micro-sprinklers dramatically.

Table 6. Application efficiency of

different irrigation systems

Irrigation System Efficiency (%)

Flood irrigation 60

Micro irrigation 80

Drip irrigation 90


8. Width of the wetted area: In the case of micro-irrigation, the wetted zone is clearly identifiable on the soil surface and therefore easily measured. In the case of drip irrigation, a profile pit must preferably be made under-neath the dripper-line to accurately establish the wetting zone width. Last mentioned is de-termined by a combination of the soil texture as well as irrigation cycle lengths.

Steps for irrigation schedule plan-ning, using weather data as well as orchard and soil characteristics (adapted from Myburgh, 1993).With the above-mentioned information in mind, a few steps can be followed to deter-mine:

• How much water needs to be applied per irrigation cycle;• How long the cycle must be to apply the correct amount of water; and• When irrigation is required, in other words, how often must the irrigation cycle be repeated.

To illustrate the process, an example of a micro-sprinkler irrigated mature orchard in Letsitele is used. The following applies to the orchard:

Canopy cover 70%

Soil texture loamy sand

Tree spacing 7.0 m x 3.0 m

Effective root depth 40 cm

Area of soil surface that is wetted 40% of the surface

Month for which irrigation requirement is calculated January

From this the ensuing information, required to draw up an irrigation schedule, can be established:

1. Calculate how much water needs to be applied?

2. Calculate the delivery rate of the irrigation system.

In case of uneven distribution of emitters, or double row drip lines, use the following calculation for this step:

3. Calculate the length of the irrigation cycle needed to apply the required amount of water.

4. Calculate how regularly (after how many days) an irrigation cycle is required.

Water Root depth % extraction % of wetted The amount of water holding (40 cm = of PAW area that must be appliedcapacity 0.4m) (40% = 40/100) (40% = 40/100) per irrigation cycle 80 mm/m 0.40 m 40/100 40/100 5.12 mm = 51 m3/hax x x =

Sprinkler/ Row Sprinkler/ % of wetted Delivery rate of the Dripper Spacing Dripper area irrigation systemdelivery Spacing (40% = 40/100) on the wetted arearate 30 L/hour 7.0 m 3.0 m 40/100 3.57 mm/hour÷ ÷ ÷ =

Sprinkler/ No of emitters % of wetted Delivery rate of the Dripper per hectare, area irrigation systemdelivery divided by 10 000 (40% = 40/100) on the wetted rate area 30 L/hour 477/10 000 40/100 3.57 mm/hourx ÷ =

Amount of water Sprinkler/Dripper delivery The length of theneeded per cycle rate on the wetted area irrigation cycle 5.12 mm 3.57 mm/hour 1.43 hrs = 1.½ hrs÷ =

Amount of Reference Crop System Time water needed evapotranspira- coefficient efficiency betweenper cycle tion (ETo) (Kc) 90% =.9 cycles 5.12 mm 4.3 mm/day 0.93 0.8 1.60 days = 2 days÷ =÷ ÷

These values are now used in the steps below:

Soil’s water holding capacity (readily PAW) 80 mm/m (from Table 1)

Extraction % of readily PAW in this phenological stage 40% (from Table 2)

Crop coefficient (Kc) 0.93 (from Table 4)

Long-term reference evapo-transpiration (ETo) for January 4.3 mm/day (from Table 3)

Application efficiency 80% (from Table 6)

Delivery rate of micro-sprinklers/drippers 30 L/hour (from the manufacturer)

Micro-sprinkler/dripper spacing 3.0 meters spacing (from orchard)


The above example shows that during Janu-ary in Letsitele, an irrigation cycle of 5.12 mm is needed every second day to replenish the water in the root zone, to field water capacity. When the delivery rate of the irrigation system is taken into account, the length of the irrigation cycles can be calculated, which is 1.5 hours for our example.

From a practical point of view, these calculations should be done monthly due to variations in ETo and Kc values. Separate calculations are also required where there are differences between irrigation management zones, e.g. soil type, canopy cover, tree age, or any aspect that might influence ET.

The above-mentioned method for determining the irrigation requirement serves as a theoretical schedule, but makes provision for differences in tree canopy cover, type of irrigation system and soil type. These factors are generally constant for the duration of a season, except for the short-term variation in atmospheric demand (ETo) and rainfall. The correct amount of water required for irrigation may, however, differ from these calculated values, due to inaccurate estimations of soil water holding capacities and/or diversions in the current weather condi-tions from the long-term weather patterns. As mentioned, the above calculations are used for setting a theoretical irrigation schedule or irrigation plan and serve as a starting point. Irri-gators should then be fine-tuning the proposed irrigation schedule by doing on-farm monitoring of the soil water content with a soil auger or physical profile inspections. In this way, trends of over- and under-irrigation will be avoided. Different technologies are available to measure or estimate the soil water content, but are not discussed in this article.

One of the simplest ways to determine soil water content, or calibrate readings from any apparatus, is still by means of in-situ soil inves-tigations, i.e. feeling the soil water content with one’s hand. From an irrigator’s perspective, the use of long-term weather data (to develop a ba-sic irrigation schedule), combined with measure-ments of soil water content (to ensure that they do not tend to over- or under-irrigate over time), facilitates the accuracy of when and how much water to apply.

The value of soil profile examinationsIn Table 7 criteria are listed for using the “feel-test”, to determine soil water content. This is done after removing soil with a soil auger, or from the side/bottom of a profile pit. Soil profile pits are the preferred choice for farmers or irrigators, because more insights are gained of important elements that may influence the decision making process on when and how much to irrigate, such as: plant root develop-ment, soil-root system health and the soil water distribution.

Soil profiles are investigated for various reasons, but when the purpose is for irrigation scheduling, the following need to be considered:

1. Soil water content – as described above (Table 7).

2. Soil water distribution – the presence of soil layers that are water saturated for long periods, or compacted layers/rock that obstruct effective drainage, need consideration in the irrigation plan. The wetting depth of irrigation cycles also needs to line up with root distribution.

3. Soil texture – ensure that the correct soil texture class is used for estimating the soil water holding capacity.

4. Root distribution – the correct soil volume should be used to calculate the soil’s water holding capacity.

5. Root health – establish if the root system is healthy and effective in utilising the applied water, or if over-irrigation occurs that negatively affects the roots.

Soil water content Characteristics of soil (% of plant available (a handful of soil pressed in the palm of the hand)soil water that is left)

0-25 Soil is too dry to squeeze in a ball – it crumbles

25-50 Soil can be squeezed into a poorly bound ball

50-75 Soil can be squeezed into a well-shaped, stable ball

75-100 Water is left behind on hand, after pressure was applied – no free water

FWC* Free water is visible – soil flows through fingers when squeezed

*FWC = Field water capacity

Table 7. Criteria used to determine the soil water content


Choice of irrigation systemBoth drip and micro-sprinkler irrigation systems are popular in SA. Traditionally, micro-sprinkler irrigation systems were pre-ferred, due to the ability of these systems to irrigate a larger soil volume. This led to the belief that orchards are better protected against heat waves and a micro-climate is created that benefits the orchard. The emphasis on Integrated Pest Management (IPM)

also requires a cover crop between tree rows, which necessitates an irrigation system that can supply water to the work row. Many people also have difficulty managing drip irrigation systems properly, especially in the hot areas, where sudden heat waves often result in yield and quality losses.

A steady increase in the number of orchards established with drip irrigation has occurred over recent years. This is mainly due

to improved drip and fertigation technol-ogy and products, agronomic support, on-farm managerial skills and increased pressure on water resources. Another factor that contributed to the popularity of drip irrigation is the concept of fertigation, or rather precision farming, where con-cepts of open hydroponics are utilised to promote more efficient utilisation of water and fertilisers. Growers in SA are world leaders when it comes to the use of low delivery rate drippers, and implementing the concept of a “centralised control con-tinuous irrigation system”.

In most respects, the choice of an irriga-tion system depends on the producer’s preference, and to a certain extent, the reliability of fresh water supply. A prerequi-site for successful drip irrigation, however, is a well-established deep root system that can only be obtained with proper soil preparation.

Some interesting irrigation facts to bear in mindAverage annual total water use by citrus (Mostert, 1999). 900 -1010 mm 9000 - 10100 m3/ha

Phenological stage when water stress has an irreversible effect on fruit quality (Mostert, 1999).

Phase 1: cell division

Phenological stage when irrigation can be withdrawn with the least effect on the trees or the crop (Mostert, 1999).

Postharvest (July)

Daily water use of Valencias (Mostert, 1999). Winter: 2 mm/day Summer: 5.2 mm/day

Cultivar with the highest average daily transpiration Nadorcott Mandarin(Vahrmeijer & Taylor, 2019). 4.5 mm/day

The percentage that transpiration is reduced when the leaf area index of trees is reduced from 6.9 m2/m2 to 4.8 m2/m2 (30%), through aggressive pruning (Vahrmeijer & Taylor, 2019).

52%

Percentage of ET that is made up by evaporation from Citrusdal: 65-91%the soil surface (Es) (Vahrmeijer & Taylor, 2019). Lesitele: 19-45%

Maximum daily atmospheric evaporative demand (ETo) at which no further increase in transpiration occurs (Vahrmeijer & Taylor, 2019).

5 to 6 mm/day

Pieter Raath, CRITeunis Vahrmeijer, Villa Crop Chris Malan, Netafim


SummaryIn a country where water for irrigation of orchards is becoming less available, producers are forced to invest more financial resources in strategic planning and technology to improve their irrigation practices. The principles set out in this article help to achieve the most efficient use of water, as well as application of accurate irrigation volumes, for optimal tree performance. The four aspects that need to be attended to are:

• Establish the soil’s water holding capacity, as well as the opti-mal percentage extraction of the readily plant available water for

each phenological stage, so that the amount of water that needs to be applied per irrigation cycle can be established.

• Using the calculated delivery rate in mm/hour, calculate the length of the irrigation cycle.

• Using the ETo, Kc and amount of water needed per cycle, calcu-late how long the period between irrigation cycles must be.• Finally, check the soil water content regularly to avoid grad-ual trends of under- or over-irrigation and make the necessary adjustments if required. ✤

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Anagyrus pseudococci - 'n baie effektiewe witluisparasiet.

Literature citedmostert, P.G., 1999. Die invloed van watertoedieningsopsies op die produksie van sitrus (Citrus sinensis Var. Valencia). MScAgric Thesis, Department of Soil Science, University of the Orange Free State, 80pp.

FAliVene, s., GiDDinGs, J., hArDy. s. & sAnDerson, G., 2006. Managing citrus orchards with less water. NSW Dept. of Primary Industries.

myBurGh, P.A., 1993. ŉ Vloeidiagram vir die berekening van besproeiingskedule vir wingerd. Wynboer, Sep., 10-11.

VAhrmeiJer, J.t. & tAylor, n.J., 2019. Quantifying citrus water use and water stress at orchard level. Volume 2: Measurement and modelling of seasonal citrus water use for different growth stages and canopy sizes. WRC Report No YY 772/2/18, 175pp.

PROMOSIE


IntroductionLarge navel-end openings can provide a refuge for insect pests, such as mealybugs, which protect them against control measures (Ber-linger and Goldberg, 1978; Hattingh et al., 1995; Moore et al., 1997). Foliar application of the plant growth regulator and synthetic auxin, 2,4-dichlorophenoxy acetic acid (2,4-D), during flowering reduces the size of the navel-end opening and the proportion of navel-ends that are open (Mupambi et al., 2015; Stander et al., 2017). The ideal timing for optimal results for such an application is during full bloom (Mupambi et al., 2015). Consequently, 2,4-D is registered for such use on Navel oranges as a medium cover diffuse spray (in combination with tebuconazole) (Stander, 2018). This inhibits the premature development of micro-cracks on the fruit style, caused by ethylene, which results in its eventual abscission (Stander et al., 2014). In addition, 2,4-D stimulates growth of the rind tissues at the stylar-end of the fruit which results in a stronger rind and reduced susceptibility to stylar-end fruit splitting (Cronjé et al., 2013; Stander et al., 2014). Here we report on some trials that investigated the role that the reduc-tion in open navel-ends played in infestation lev-els of mealybug and false codling moth (FCM).

Materials and methodsOver a three-season period, 2008 to 2011, 2,4-D was applied to citrus trees in spring in several trials conducted in Navel orange orchards in the Western and Eastern Cape. Either 2,4-D Ester or 2,4-D Amine was used at rates ranging from 5 to 25 ppm at full bloom or at petal drop. The adjuvant, Break-Thru (polyether-polym-ethylsiloxane-copolymer) was added to each spray mixture at a rate of 5 ml per 100 L water. Medium cover diffuse sprays were applied using a hand gun sprayer. In all the trials, each treat-

ment consisted of eight single tree replicates in a randomised complete block design with buffer trees between treated trees.

At three of the sites, mealybug infestation was at a level that evaluation of differences in infesta-tion between treatments could be justified. One was an orchard of Washington Navels in Citrus-dal, Western Cape, during the 2008/09 season; the other two were Autumn Gold Navel orchards in Heidelberg, Western Cape, during 2008/09 and 2009/10. All results reported are for sprays applied at full bloom.

Mealybug infestation of fruit was evaluated during May for the first two trials and during December for the third trial. This was done by inspecting 10 fruit on each tree (in the navel-end and under the calyx) and recording percentage of fruit infested.

At 10 sites, fruit with FCM eggs was determined, again by inspecting 10 fruit per tree during May. Additionally, FCM larval infestation of fruit was recorded at three sites (Palmer Navels during 2009/10 and two orchards of Newhall Navels during 2010/11, all in the Sundays River Valley, Eastern Cape) by collecting and dissecting fallen fruit under all trial trees on a weekly basis, for a 15-week period from January to April.

At commercial maturity, approximately 80 fruit were collected from all sectors of each tree in each treatment. The percentage of fruit with closed navel-ends was calculated by dividing the number of fruit with closed navel-ends by the total number of fruit (80) evaluated per replicate tree.

Values were compared between treatments by using an ANOVA and LSD multiple range test (Statistica Version 14.4.0.14, 2018).

Results and DiscussionReduction in open navel-ends

Of the 13 sites where navel-end diameters were

Do smaller navel-ends mean lower pest levels?

SEAN MOORE1,2, WAYNE KIRKMAN1, STEPHAN VERREYNNE1,3 AND GIVERSON MUPAMBI4

1Citrus Research

International;

2Centre for Biological

Control, Rhodes University;

3Nulandis;

4Department of Horticulture,

Stellenbosch University


measured, the proportion of navel-ends closed versus open was significantly increased for at least some of the 2,4-D applications at 10 of the sites. Of the three sites where mealybug infes-tation was evaluated, a higher percentage of navel-ends was closed for all 2,4-D treatments, relative to untreated fruit (Fig. 1). This was signif-icant at two of the three sites.

Mealybug infestationA lower percentage of fruit treated with 2,4-D, and thus with reduced open navel-ends, was infested with mealybug (Fig. 2) at all three sites evaluated. At two of the sites, this was signif-icantly so, at least for some of the treatments (Fig. 3). This is supported by the findings report-ed by Stander et al., 2017.

Not only would the closing of a significant proportion of navel-ends dramatically reduce the available protected sites for infestation of mealybug on fruit, but mealybug would now be more exposed to chemical sprays and bio-logical control. Moore et al., 1997 demonstrat-ed that parasitism of citrus mealybug by Coccidoxenoides perminutus, was 2.6 times higher under the fruit calyx than in the navel- end, demonstrating the high degree of protec-tion of mealybug provided by the navel-end.

FCM infestationAt none of the 10 sites monitored was there any

significant difference in numbers of FCM eggs laid on fruit between any of the treatments. Nor was there any significant difference in FCM in-festation of fruit between any of the treatments. Consequently, navel-end size, as manipulated by 2,4-D application, made no notable differ-ence in the attractiveness of Navel oranges to FCM, nor to the susceptibility of the oranges to infestation by FCM (Fig. 4). It has been anecdo-tally reported by some that Navel oranges with larger navel-ends are more susceptible to FCM attack. However, it appears that this is related to the Navel cultivar, some of which tend to have larger navel openings than others, rather than to the size of the navel opening.

ConclusionThe application of 2,4-D to Navel oranges dur-ing full bloom generally, and often significantly, reduced the proportion of open navel-ends. In turn, this reduced the proportion of fruit infested with mealybug, as the accessibility of the protec-tive navel-end was reduced. However, reduction in navel-end openings did not reduce FCM infestation.

Fig. 2. Mealybug infesta-

tion within the enlarged

navel-end of a Navel

orange (PHOTO: PETER STEPHEN).

Fig. 1. Percentage of navel-

ends closed at A. 2008/09

Washington Navel site,

B. 2008/09 Autumn Gold Navel

site, and C. 2009/10 Autumn

Gold Navel site


OpsommingGroot nawelente kan 'n skuilplek bied vir insek-plae soos witluis, wat hulle dan teen beheer-maatreëls kan beskerm. Bespuiting van die plantgroei-reguleerder en sintetiese ouksien, 2,4-dikloorfenoksie-asynsuur (2,4-D), tydens blomtyd, verminder die grootte van die opening van die nawelent en die hoeveelheid nawelente wat oop is. Die toediening van 2,4-D

op Nawel-lemoene tydens volblom in die Oos- en Wes-Kaap, het oor die algemeen, en dikwels betekenisvol, die proporsie van oop nawelente verminder. Gevolglik is die hoeveelheid vrugte wat met witluis besmet is, verminder, aan-gesien die toeganklikheid van die beskermende nawelent verminder is. Inteendeel het vermin-dering in nawelent-openings egter nie vals-kodlingmotbesmetting verminder nie. ✤

Fig. 3. Percentage of fruit

infested with mealybug at

A. 2008/09 Washington

Navel site, B. 2008/09

Autumn Gold Navel site

and C. 2009/10 Autumn

Gold Navel site

Fig. 4. An FCM larval pene-

tration mark on the side of

a Navel orange, despite the

existence of an enlarged

navel-end

ReferencesBerlinGer, m.J. AnD GolDBerG, A.m. 1978. The effect of the fruit sepals on the citrus mealybug population

and on its parasite. Entomologia Exp. Appl. 24, 38-43.

cronJé, P.J.r., stAnDer, o.P.J. AnD theron, K.i. 2013. Fruit splitting in citrus. Hort. Rev. 41, 177-200.

hAttinGh, V., tAte, B. AnD richArDs, G. 1995. The effect of mealybug infestation on the incidence of

post-harvest Alternaria decay in navel oranges. Citrus J. 5 (2), 18-19.

moore, s.D., hAttinGh, V. AnD tAte, B.A. 1997. Practical considerations in augmenting Coccidoxenoides

peregrinus (Hymenoptera: Encyrtidae) for control of mealybug on citrus. In: V Hattingh (ed), Mass rearing

for augmentation, Fifth National Insect Rearing Workshop, pp.13-15.

muPAmBi, G., Verreynne, J.s., stAnDer, o.P.J. AnD cronJé, P.J.r. 2015. Optimal timing of application of

2,4-D on ‘Navel’ sweet orange [Citrus sinensis (Osbeck)] reduces the size of the navel-end. J. Hort. Sci.

Biotech. 90 (6), 619-625.

stAnDer, o.P. 2018. Reduction of navel-end opening size and Alternaria black core rot. Cutting Edge no 251.

stAnDer, o.P., GilBert, m.J., moore, s.D., KirKmAn, W. AnD schutte, G.c. 2017. Benefits of reducing the

size of the navel-end opening in ‘Navel’ sweet oranges (Citrus sinensis). Crop Protection, 96, 123-129.

stAnDer, o.P.J., theron, K.i.t., cronJé, P.J.r., 2014. Foliar 2,4-D application after physiological fruit drop

reduces fruit splitting of mandarin. Hort. Technol. 24(6): 717-723.

84 TEGNOLOGIE | FEB/MAART 2020

Previous research on olive fruit fly showed that many olives thought to be infested with fruit fly were actually infested with indigenous olive seed wasps. At least

five seed wasp species have been identified in wild olives (Olea europaea L. subsp. cuspidata) in the Western Cape. Consequently, a team of researchers from ARC Infruitec-Nietvoorbij, the Department of Genetics at Stellenbosch University, and Palermo University in Italy con-ducted research to determine which of these species attack cultivated olives, and whether any of them pose an economic threat to the olive industry. The research was funded by SA Olive, the NRF Research and Technology Fund and the Agricultural Research Council.

Here are the research outcomes:

Identification of olive seed wasps in cultivated olivesAdult wasps can be identified by morphological features. A molecular method for rapid identifi-cation of Eupelmus spermophilus and four other potential seed wasp species was developed by the project team. This is particularly useful for identification of larvae and pupae that cannot be identified using morphological features. Observations over three years confirmed that of

the five species E. spermophilus (Fig. 1) is the primary seed wasp attacking cultivated olives in the Western Cape.

Seasonal occurrence and distributionYellow sticky traps are useful to indicate when olive seed wasp (OSW) males and females are active in wild olives and in orchards, but they are not reliable indicators of OSW infestation levels in cultivated olives.

Sticky trap results showed that OSW adults are active in orchards during spring and summer when developing olives are available, and in February/March when adults emerge from infested olives, but not during winter. Field observations confirmed that OSW does not overwinter in cultivated olives.

Adult OSW are active in wild olives all year round. Unlike cultivated varieties, wild olives have more than one flowering cycle during the year, largely depending on the availability of water. As a result, wild olives at different phe-nological stages are present all year round. This ensures the regular availability of young olives with soft kernels (seeds) in which OSW eggs can be laid. Olive seed wasp overwinters and re-produces in wild olives during times of the year when there are no cultivated olives available.

ELLEUNORAH ALLSOPP, BARBARA VAN ASCH,

MURIEL KNIPE, CHRISTIAN GIACALONE

AND VIRGILIO CALECA

OLIVE SEED WASPS IN CULTIVATED OLIVES

Possible threat

Figure 1. Olive seed wasp

(Eupelmus spermophilus)

female (A) and male (B)

A B

85FEB/MARCH 2020 | TECHNOLOGY

A

Table 1. Olive seed wasp (OSW) infestation, yield for sample trees, and yield

loss (fruit drop due to olive seed wasp infestation) over three seasons in two

cultivated olive orchards in the Western Cape

% OSW infestation Yield for % Yield loss Location Harvest Dropped Fruit picked sample trees due to Year fruit at harvest (kg) dropped fruit

Stellenbosch 2016 0 0 150 0

(11 trees) 2017 79 19 188 14

2018 66 7.7 205 1.3

Agter-Paarl 2016 64 16 667 1.8

(36 trees) 2017 59 18 50 12

2018 3.8 0.28 571 0.03

Figure 2. Olive seed wasp pupa and

black meconium in pit (A) and adult

emerging from the seed (B)

All the areas in the Western Cape where olives are cultivated in the vicinity of wild olives, had OSW present. They primarily attack cultivars with smaller fruit, mostly the oil cultivars. They do, however, occasionally attack larger table olive cultivars (such as Manzanilla), if the fruits of these cultivars are still small enough when female olive seed wasps are ready to lay eggs.

Economic damageThe OSW female lays an egg in the soft kernel of the young olive fruit, before the pit hardens and the fruit pulp is too thick (>1.5 mm) for her ovipositor to reach the kernel. The larva and pupa develop inside the kernel (Fig. 2A) until the adult seed wasp emerges (Fig. 2B), leaving a small exit hole with a clear edge that becomes corky after some days (Fig. 3).

Many olives infested by OSW fall from the tree before ripening, resulting in direct yield loss. Some infested olives, with or with-out exit holes, remain on the trees to be harvested and pro-cessed. To date, there is no evidence that these infested olives have a negative impact on oil quality, but olives with emergence holes are unsuitable for processing as table olives.

Yield of the sample trees and yield loss due to dropped fruit infested with OSW varied greatly between the two field trial sites and seasons (Table 1). Yield loss due to OSW was highest

at both sites during 2017, but negligible during 2016 and 2018. Olive seed wasp infestation in dropped olives and yield loss did not correlate consistently with weather data.

Conclusion Olive seed wasp infestation only poses a risk to cultivated olives grown in the vicinity of wild olives, which act as overwintering sites and sources of infestation. While OSW does not pose a sig-nificant threat to the industry as a whole, it can have a significant impact on yield where cultivated olives grow in close proximity to wild olives. The sporadic nature of economically significant OSW infestation complicates decision-making regarding control, since it was found that sticky traps and weather data are not reliable indicators of potential infestation levels. The presence of abundant wild olives near olive orchards during the preceding summer and autumn can result in large numbers of OSW emerg-ing early in the following growing season when cultivated olives are susceptible to OSW oviposition. This can result in econom-ically significant OSW infestation and yield loss. Currently, no chemical control is registered for OSW in cultivated olives. ✤

B

Figure 3. Olive seed wasp emergence hole

For further information, contact Dr Elleunorah Allsopp at [email protected] or 021 809 3007.


ELMARIE DE BRUYNCell: 082 562 2343 | [email protected]

AT THE KITCHEN TABLE

It’s summer! Seasons, which are older than

civilisation itself, are a part of the rhythm of our human lifecycle, and

our understanding of them is relative to places, dates and the person/

people involved.

Summer is my special time of the year when I am reminded of sunshine, sunglasses and sunflowers; sea,

sandcastles and swimsuits; sailing, sunsets and sunhats; and most of all,

scents and flavours. Not forgetting braais and cool

summer drinks. They all take me back to my childhood.


Pineapple sparkler with mintThis refreshing tropical drink is sweet and zesty at the same time.

½ cup sugar1 cup lemon juice1 pineapple pureed2 tablespoons lime juice6 cups water1 sprig mint leaves (to taste)

For the syrup, combine the sugar with one cup of water in a medium saucepan over medium heat, stirring until the sugar has dissolved. Add some mint leaves and allow to cool.

In a large pitcher, whisk together the syrup, lemon juice, pineapple puree, lime juice and the remaining five cups of water. Chill, then serve on ice.

Watermelon coolerSo sweet. So tasty. So summery.

5 cups diced seedless watermelon, chilled | 2 tablespoons sugarJuice of 1 lime5 basil leaves | 1 cup ice

Combine watermelon, basil, sugar, lime juice and one cup of ice in a blender until smooth. Serve immediately, on ice.

Berry and peach iced teaSo fruity and herby.

tea | herb infusion1 cup raspberries, black berries, or any other berry | 2 peaches 3 tablespoons maple syrup

Make a black and rooibos tea blend and

allow to cool. Or you can simply chill any

recent leftover tea in a pitcher, in the

fridge. Then make a peppermint gera-

nium and lemon verbena infusion, and

leave to cool. Combine peaches, rasp-

berries and maple syrup in a blender,

until smooth. In a large pitcher, whisk to-

gether raspberry and peach mixture, tea

and the herb infusion. Chill, then serve

on ice, with raspberries, peach slices and

herb leaves (optional).

Sparkling cherry lemonadeThis sparkling, fruity drink is just as easy to prepare.

½ cup cherries, pitted¾ cup freshly squeezed lemon juice²/³ cup sugarFresh rose geranium leaves4 cups sparkling water

To make the cherry syrup, combine cher-ries, lemon juice and sugar in a blender, until smooth. Add rose geranium leaves to the mixture and allow to infuse for a few hours. Chill, then serve on ice.

Strawberry coolerThe fresh fruitiness of this drink is unmistakable.

½ cup lime juice | 1/³ cup sugar1/³ cup water | 1 kg sliced strawberries20-30 mint leaves | 20 red rose petals2 cups cold water

Make a syrup by combining the sugar and water in a saucepan, bringing it to the boil over a medium to high heat. Remove after 5-10 minutes, when the sugar has dissolved and the liquid is clear. Then, combine all the ingredients in a large jar or pitcher. Chill for 2-3 hours and enjoy with ice.

Melon sorbet floatWhat would a summer drinks menu be without a fruity float?

Assorted melon balls - honeydew, cantaloupe2 scoops lemon, raspberry, or any other fruity sorbetFresh mint leaves | sparkling water

Freeze the melon balls for at least three hours. Place the sorbet at the bottom of a glass, and top with frozen melon balls. Add fresh mint to taste and top up with sparkling water. Allow the sorbet to melt, to sweeten and flavour the drink.

COOL SUMMER DRINKSIt’s a real joy to have chilled drinks in the fridge in summer. And with so much extra time on our hands, we may as well prepare them ourselves, with fresh seasonal ingredients and our favourite herbs. These recipes are mostly basic, which allows for some imagination and creativity.


How did you become involved in the SA top fruit industry?“That is a long story,” says Henk with a laugh. “After complet-ing school, I decided to study Horticulture and Botany and I received a bursary from the Deciduous Fruit Board. My choice was inspired by my fascination with plants as a youngster, and by my many walks on Table Mountain while I was at school. My first job within the deciduous fruit industry was running the maturity lab in Grabouw under the supervision of Richard Hurndall, where we sampled fruit from most of the Western and Southern Cape production regions, stretching from Langkloof to Piketberg.”

What does your job at Tru-Cape entail? “I am responsible for all production, packing and postharvest technical issues at Tru-Cape. This includes new cultivars, due diligence, IFS broker compliance, shipping regimes, postharvest handling, quality standards and all quality related claims and complaints.”

What inspired the writing and publication of the Early Apples at The Cape publication with Buks Nel? “Buks Nel has been working with top fruit varieties for many years, and in his orchards there are hundreds of apple and pear varieties. With all the new varieties currently being planted to replace older varieties, we wondered what the old ones that are no longer in commercial production were like and why they had been replaced. That question inspired this initiative, as we wanted to find references to these old varieties and where they had orig-inated. At times it proved very difficult to find local references and as a result, Buks came up with the idea of writing a book so that the information would be easily available for future reference to those interested in this fascinating topic.”

What has been the response to the publication? “As one would expect, very positive and we have turned up some unexpected re-sults from when Buks and I started out with the research for the pub-lication. It has been a fascinating journey and to add to this, Buks is currently writing a follow-up book that deals with all apple varieties up to the present day.” The passion that Henk and Buks share for old apple varieties also led to the identification of South Africa’s oldest apple tree, which is more than a century old and was found growing at the top of Table Mountain, of all places! The search for old apple varieties also yielded information about the first apples planted in the Company Gardens in Cape Town. In his diary, Jan

van Riebeeck recorded harvesting fruit from Witte Wijnappel trees in the gardens in 1662. As a result of this, Tru-Cape and Hortgro were part of an initiative to import budwood of the Witte Wijnappel apple variety from Holland, to replant this variety in the Company’s Garden in Cape Town. After the mandatory period in quarantine and growing the seedling in April 2019, a tree-planting ceremony was held in the Company’s Garden heritage site in Central Cape Town to plant the young Witte Wijnappel tree. This initiative was completed in cooperation between Tru-Cape, Hortgro, the City of Cape Town and the Heritage Fund. This passion for old apple varieties within Tru-Cape has also led to the establishment of the Tru-Cape Heritage Orchard at Oak Valley Estate at Grabouw.

How has your job impacted on your private/family life? “My private life and working life have always been very inter-twined. After I completed my Honours degree, I spent a year in Chile at a time that it was unusual and very difficult for a South African to go abroad for work in the fruit industry. At that time Chile was a minor top fruit exporter, while SA was one of the largest apple exporters. To be honest, I think that I learned more about myself during that year than at any time since!”

Has there ever been a particularly significant or humorous moment in your career that you would like to share? “Yes, there was an incident that was somewhat astounding. This hap-pened while I was working in Chile, in a town south of Santiago called Rancagua. On a Sunday in winter, I was on a bus travelling to another town and looking out the window I spotted none other than Professor Strydom from the Department of Horticul-ture at Stellenbosch University, walking in the street beside the bus! Professor Strydom had been one of my lecturers and I could not believe my eyes, as he must have been the first South African that I had seen in six months.”

Do you have a message for SA top fruit industry stake-holders? “I think the top fruit industry is rapidly changing with technology, varieties and climate. We need to ensure that we remain grounded and focussed on the fundamental issues with regards to production. A tree grows from its roots and there will be nothing to prune or to bear if the roots are not happy. For the ongoing sustainability of our industry, it is vital that we do not lose our focus on the basics of successful fruit production.” ✤

HENK GRIESSEL is the technical and quality assurance manager at Tru-Cape fruit marketing company. In addition to his job, Henk has a real passion for old apple varieties. He and his colleague, Tru-Cape Variety Specialist and top fruit grower Buks Nel recently published a book called Early Apples At The Cape. It identifies and describes the origins and characteristics of these scarce treasures.

THE LAST WORD | LOUISE BRODIE

Kontak Johan Wiese of Andrew Teubes:Tel: 021 864 1018 Faks: 021 864 3689 e-pos: [email protected] www.vgnurseries.co.za

SUKSES WORD GEKWEEK

Voor-Groenberg Kwekerye het die kennis, integriteit en ondersteuning wat verseker dat jou belegging in die beste plantmateriaal vir wyn-, droog en

tafeldruiwe, ruim dividende sal betaal.

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