cropping central issue 53 - department of agriculture and ......march clermont club, 48 sirius st,...

Queen Weedy bows outDarren Aisthorpe, Extension Agronomist, CQ Grower Solutions, DEEDI, Biloela

After more than 25 years of service with DPI and DEEDI, CQ’s Principal Research Scientist (Weeds) and Weed Sciences Team Leader Vikki Osten accepted a voluntary separation package and retired on 10 February this year.

Vikki initially studied at the Queensland Agricultural College (now University of Queensland, Gatton) in the ‘early 1980s’, completing a Bachelor of Horticultural Technology (Honours) majoring in plant protection and specialising in weed science. From uni, she was employed at the Queensland Wheat Research Institute (QWRI) for two years before accepting her position in CQ.

Vikki first arrived in CQ in June 1987, spending two weeks in Biloela with Steve Walker, Regional Weed Agronomist, before moving across to Emerald as Steve departed to undertake further study in Western Australia. In 1988–89, she was seconded to Indonesia to work on a project (funded by the Australian International Development Assistance Bureau and the World Bank) to improve weed management in rain-grown cotton, which was a tremendous opportunity at the time.

On her return to Australia, she focused on a number of different projects, including assessing plant-back periods for products such as 2,4-D and dicamba for CQ conditions. This work resulted in label changes and reduced plant-back periods.

Ray Meany and Vikki Osten discuss feathertop Rhodes management

She also worked on a perennial weed management program that included a biological and ecological study of raspweed, funded by the Queensland Grain Committee; a Grains Research and Development Corporation (GRDC) project looking at the

In this issueQueen Weedy bows out

Editor’s etchings

Two hit combo—making the second knock count!

Hitting the target—tips from Bill Gordon on optimising Group L application

Double knock in practice

Central Queensland NVT trials 2011

Consultant profile: Graham Spackman

Case study: Taking on new technologies for improved efficiency and sustainability

Getting back to spraying basics

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Cropping CENTRAL Issue 53

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management of Peak Downs curse, raspweed, grey rattlepod, teucry weed and nutgrass; and a National Heritage Trust funded project addressing bitter bark management.

During the early 1990s, Vikki completed a Master of Agricultural Science (by research) through the University of Queensland. In the early to mid 1990s, she undertook research into CQ plant-back periods (the interval between spraying and safe re-planting of crops) for herbicides such as Glean®, Ally®, Atrazine®, Flame® and Spinnaker®. This work covered most of the major crops grown within the region and provided a much greater understanding of the characteristics of residual herbicides within the CQ environment. Data were provided to industry to enable herbicide label changes.

In the mid-1990s, the importance of ley legumes was beginning to come to the fore within CQ and the need to manage weeds within these crops was identified as a high priority. Vikki conducted research on weed control in lablab, desmanthus and butterfly pea through a joint project led by the CSIRO, and then continued research into weeds within butterfly pea pastures through the CQ Sustainable Farming Systems (CQSFS) project in the late 1990s.

Vikki has been a long-serving and integral participant in the CQSFS project since it began in 1997. In 2003, a separate GRDC funded weeds research project for CQ began with Vikki supervising a new scientist (Gavin Lotz) to address management of difficult weeds, weed management in wide row crops and improvement of herbicide efficacy under adverse conditions. Meanwhile, Vikki was also leading a national project and participating in two others in the final phase of the Weeds CRC. In mid-2007, Vikki resumed research responsibilities in the CQ weeds project after Gavin moved to a permanent position and new role in Biloela.

Some of Vikki’s work in CQ has included:

CQSFS project (1997–2010) and then CQ Grower Solutions project (2011–12)

• Continued the butterfly pea weed work•On-farm weed monitoring•Weedies Road Show—seven venues around CQ• Sunflower weed management• In-crop WeedSeeker use in conjunction with the Fitzroy

Basin Association•Wheat cultivar herbicide tolerance work• Chickpea in-crop weed control• Development and extension centred on management of

feathertop Rhodes grass

CQ weeds research project (2003–11) and components of other northern region weeds research projects (2005–11)

• Feathertop Rhodes grass biology and management research•Weed management in wide-row cropping systems• Improving chemical efficacy under adverse conditions• Integrated Weed Management (IWM) workshops•Herbicide resistance research and development work

resulting in the Stopping herbicide resistance in CQ brochure

• A comprehensive scoping study of north Queensland, central Queensland and near-coastal cropping systems

Weeds CRC and Cotton CRC research projects (2002–08)

•Water and nitrogen use by summer fallow weeds•Weed management in dryland cotton systems•Weed management risks in wide-row crop systems

When asked to reflect on her time in Emerald and at the Emerald DEEDI office, Vikki sat back and came up with some pretty amazing facts. ‘Since starting in Emerald, I have seen over 100 staff come and go; been through at least four departmental restructures; been through a major office upgrade; seen water go over the dam spillway six times; seen two major and three minor floods; and seen the town grow from 6000 residents to over 12 000 today. I also got married here and my son was born in the Emerald hospital—he is a local but I am not—even after 25 years!’

‘National recognition of her work through the CRCs’ was Vikki’s response when asked about highlights of her career to date. ‘Closely followed by a strong sense of satisfaction achieved when able to interact with local growers and help solve the issues they are facing.’ Her third highlight was one I was not expecting, ‘Earning the nickname Queen Weedy.’ She had earned it from the her weeds team colleagues some years ago and now wears it somewhat as a badge of honour or a tick of recognition from her workmates.

When asked if there were any regrets about leaving, her response was twofold. ‘On a personal level, like many retiring scientists, there is always the regret that I didn’t publish enough. But on a broader level, probably the loss of specialist weed research capacity to CQ and its unique climatic conditions is disappointing; having all the research conducted in southern Queensland and having the specialists visit from the south is not the same.’

So what does the future hold for the abdicating Queen of Weeds? Vikki indicated that she would be staying in Emerald. ‘Emerald is my home. I have no plans for moving away at this point in time.’ She is still unsure what her next career moves will be, but she does have a few options on the table that she is currently assessing. Given her passion for weed management is still there, don’t be surprised to see Vikki making a few guest appearances at various field walks and meetings from time to time.

What’s new in managing problem weeds in CQ?

Participate in a 1-day workshop for grain growers and advisors on what’s new in managing problem weeds in CQ, particularly focusing on feathertop Rhodes grass, barnyard grass, fleabane and sow thistle. Topics include:

• Updates on herbicide resistance.• Information on weed seedbanks and management.• The past 25 years and what the future 10 years hold.• How do glyphosate tolerant crops impact on our problem weeds?• The latest information on strategies, new products and research.

Dates  Venue 

Tuesday 20th March  Clermont Club, 48 Sirius St, Clermont 

Wednesday 21st March  Main conference room, DEEDI, 99 Hospital Rd, Emerald 

Thursday 22nd March  SeElers Motor Inn, 58 Dawson Hwy, Biloela 

For workshop registration visit www.icanrural.com.au or call 02 9482 4930.

Note: Through support from the GRDC and BASF,Bayer CropScience and Crop Optics, the cost is $55 (incl. GST) per person. Numbers are limited to 20 per workshop. Pre registration is essential.

Advertisement


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Two hit combo—making the second knock count!Darren Aisthorpe, Extension Agronomist, CQ Grower Solutions, DEEDI, Biloela

Editor’s etchingsDarren Aisthorpe

Feathertop Rhodes is a massive issue for grain growers in many regions across Queensland and northern New South Wales. Management of the weed requires a multi-strategy approach to minimise seed set through a range of practices—including tillage when all else fails.

Which seems to happen more often then we would like!

What’s different for CQ, when compared to southern Queensland and northern New South Wales, is that we got feathertop Rhodes before we got flaxleaf fleabane. Why is this so different? Put simply, many growers in our region are only just starting to dabble in double knock applications—including the use of glyphosate (Group M) or haloxyfop (Group A) followed by a bipyridyl (Group L) herbicide—whereas those that have dealt with fleabane for some time have grown to understand and appreciate the benefits of the practice. To date, there have been some very mixed results with double knocking at a commercial level, despite excellent results at trial and demonstration levels, which is not assisting in uptake of the practice.

In an attempt to improve grower understanding of the double knock tactic, both for feathertop Rhodes and fleabane management, we have pulled together the ‘Two hit combo’ and ‘Hitting the target’ articles. We have taken

your questions from field walks and put them to some of Australia’s leading authorities on the technique. We hope they will be an excellent resource for those that are considering the practice.

The DEEDI NVT team is back again this year with all the latest data from the National Variety Trials across CQ last year. This is an excellent source of information for all your 2012 winter planting decisions. Take the time and have a good read through what winter crop varieties performed best in your region in 2011.

Finally, with a heavy heart, the team says goodbye to one of the few remaining founding members of the CQ Sustainable Farming Systems team, Vikki Osten, as she moves on to greener pastures. Vikki has worked within DEEDI and DPI in CQ for 25 years on weed management issues, and her departure will be a great loss to the project.

Hopefully you will find something of interest in issue 53 of Cropping Central. Keep an eye out for future crop walks coming up in your area soon.

I look forward to catching you all out in the paddock soon!

Cheers,

Darren

What is a double knock?When it comes to weed management, the practice of double knocking involves the planned application of two (or more) practices to manage a target weed. The most common form of double knocking would be separate spray applications of two different chemical groups, e.g. a glyphosate (Group M) followed a few days later by a bipyridyl (Group L). A double knock could also involve any number of combinations including chemical application, tillage, burning and mulching.

The crucial element of the second knock or practice is to take out those targets that were not taken out by the first knock. This is essential, particularly when using Group A and B herbicides. If any plants survive the initial application of chemical, a resistant population of weeds will develop very quickly, rendering that chemical group useless against the target species.

The key messages when using knockdown herbicides on feathertop Rhodes or fleabane are:•Plan to double knock—spraying after plant

shutdown will compromise the bipyridyl efficacy. Don’t consider application as an afterthought. Timing is the key!

•Keep rates robust—both first and second knocks need to be applied at rates that will give the maximum chance of killing the plant.

•Keep water rates high—bipyridyls rely on contact to work. More viable droplets will cause more damage.

•Time your spray applications to avoid hot, dry, stressed conditions during the middle of the day.

Be realistic in your expectations—double knocking works best with small, rapidly growing plants. If plants are large, mature and rank, the best you can expect is to limit seed set and reduce biomass to allow a tillage event and the use of a residual product post-tillage.


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Why use Group L products?The bipyridyl group of herbicides or Group L herbicides are non-selective contact products that are very useful in rapidly inflicting a significant amount of damage to exposed plants’ cell structures. The active ingredient within these products works by using the process of photosynthesis (photosynthetic energy) to speed up the production of highly reactive forms of oxygen, including hydrogen peroxide from the water and oxygen in the plant, to destroy plant cells. The product is absorbed through the leaf and stem much more quickly than many systemic products; while the plants are photosynthesising, this process can take place quite quickly, with symptoms appearing in under an hour.

Single application of paraquat after 6 days

However because of the way the active ingredient reacts with the plant cell structure during the photosynthesis process, there is no systemic movement throughout the plant, meaning damage will only occur where droplet contact is made. This limitation means that while single applications of a bipyridyl product can appear very effective and dramatic, a more mature plant with larger root structures and stores of food (carbohydrates) will often recover.

Bipyridyl products work very well as a second knock for a number of reasons:

• different mode of action, which minimises resistance threats

• very effective on hard-to-penetrate leaf structures• useful in halting or preventing flowering and seed set• as compatible as glyphosate when it comes to mixing

and chemical antagonism. Just follow label instructions• take out small to medium seedlings if there is extra

germination between first and second knocks

• rapid reduction in biomass if wishing to apply a soil-based residual herbicide, burn or a tillage treatment at a later date

• very short rainfast period• very short plant-back period.

Systemic products versus contact productsTraditionally the vast majority of herbicides used in CQ have been systemic herbicides. Systemic herbicides have had some significant advantages over contact products for a number of reasons:

• generally have been highly effective on most weeds in CQ• very forgiving on application practices and timing• low application water rates.

When a sufficient number of ‘viable’ droplets of a systemic herbicide come into contact with a leaf or stem, there is a reasonable chance that the chemical will inflict terminal damage on the target plant. However, as minimum and zero tillage practices, which rely on chemical herbicides for weed control, have become entrenched within farming systems, herbicide resistance has emerged as a major issue.

A combination of factors—including the plant’s physiological attributes, sub-lethal dosages, poor farm hygiene and less than ideal spraying practices—have resulted in a ‘selection process’ taking place on our hardest to kill weeds, which not only survive herbicide applications but prosper. This has led to the issues we now face with plants such as feathertop Rhodes and fleabane.

These include:

•Higher rates are needed to perform the same task.• Plants seem to be able to ‘grow out’ after appearing to be

initially affected.• Performance is patchy, even at high rates, with some

plants dying and others only mildly affected.

Contact products such as bipyridyl herbicides (Group L), when used following an application of a systemic product, may be able counter some of these issues and optimise efficacy in some situations. The amount of damage inflicted by Group L herbicides is determined by the extent to which plants are covered by viable droplets.

In simple terms, the greater the number of viable droplets that land on the plant surface, the greater the damage inflicted. All technical experts strongly recommend water rates in excess of 80 L/ha (preferably 100 L/ha) to maximise coverage in a broadacre situation. Any plant material which is shielded or shaded by stubble, clods or other plant residue will be unaffected by the application.

There are two forms of active ingredient in the bipyridyl (Group L) family:• paraquat (250 g active) – found in products such as Gramoxone®, Nuquat®

and Shirquat®

– traditionally more effective on grass products than diquat based herbicides

• diquat (200 g active) – found in products such as Reglone®

– ideal for broadleaf desiccation.

Products are also available that combine paraquat (135 g active) and diquat (115 g active): • found in products such as Spray Seed®, Revolver®

– good all-round products for both grass and broadleaf weeds

– ideal for killing weed seedlings preplant and second knocks for flaxleaf fleabane.


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However if a systemic herbicide has already been applied (and has fully translocated throughout the plant and started to take effect), the additional physical damage inflicted by the bipyridyl product can be enough to finish off the weeds if conditions and application are suitable. This is why the process of double knocking has been so effective in the management of fleabane in southern areas.

What is a ‘viable’ droplet?

To be ‘viable’, a droplet must land on the target and stay fluid long enough to have a percentage of its active ingredient absorbed into the plant tissue. If droplets are too small, they can evaporate before absorption or contact with the target; if too large they may bounce off the target plant.

Air induction (AI) nozzle designs now reduce the risk of bounce occurring and improve coverage as the droplet is full of air and will splatter on contact. However as droplet size increases, the number of droplets decreases; where coverage is important, increasing water rates is advantageous.

Maximising bipyridyl efficacyThere are some key points to consider to maximise the efficacy of your bipyridyl applications.

Firstly, and most importantly, the plant needs to be as healthy as possible for the product to work most effectively. As discussed, the active ingredient works only when the plant is photosynthesising. Heat, stress or plant shutdown will minimise the amount of cell damage which can occur; hence spraying in hot, dry conditions, particularly with lower water rates, will reduce efficacy.

Secondly, photosynthesis requires sunlight! An obvious comment I know, but a good thing to remember if you want to improve the efficacy of your bipyridyl applications. Mark Congreve, formerly from Syngenta, shared the following information about why this fact is so important:

‘The reason bipyridyls don’t generally move or translocate is that they destroy cell structure extremely rapidly and before the plant has the time to translocate the product. To activate bipyridyls, sunlight is required.

‘Therefore one tactic is to apply bipyridyls early in the evening so that you get 8 hours of dark. Some product will translocate during this time which may improve control (but you have to wait for complete darkness before you start spraying as even a few minutes of light will start the process).

‘Another demo I ran at previous training workshops is to spray some weeds and then immediately (in less than 1 minute) cover half the plot with a heavy tarp and weigh it down so no light gets in. Then come back in about 48 hours. The sprayed and exposed area will be well browned out. Take off the tarp and the other sprayed weeds will look like nothing has happened. Give them some sunlight and they will have caught up within another 36 hours.’

Some experts in the field have also noted that when mixing paraquat products with Group C products (Atrazine®, Simazine® or Diuron®) and, to a lesser extent, Group I products (2,4-D, MCPA), there may be a small amount of reaction occurring between the two actives. This reaction may slow down the rate of cell destruction caused by the paraquat, allowing for slightly greater translocation than if paraquat were applied by itself. However, please note these improvements are generally minimal or will only be obvious under certain conditions.

Thirdly, keep rates robust and water rates high, particularly when targeting problem weeds in less than ideal conditions. Always maintain a water rate above 80 L/ha and use maximum label rates, as it is cheap insurance to ensuring you are optimising the efficacy of your application. Mark Congreve also indicated that bipyridyls are instantly bound to soil colloids, so if the spray water contains dirt or organic matter you will lose a lot of active very quickly.

Finally, if mixing with a phenoxy (Group I) based herbicide, remember that bipyridyls have similar compatibilities to glyphosates, and therefore there may be some antagonism between the two products. Jason Sabeeney from Syngenta advises that if mixing the two actives, you should never exceed the 2:1 ratio on the phenoxy side, i.e. 2 parts bipyridyl:1 part phenoxy.

Double knock—timing of applicationsWhen should you apply a second knock? The simple answer is ‘before the weeds start shutting down from the initial knock’. You have to time the gap between the two applications so that the initial application—e.g. a glyphosate (Group M), haloxyfop (Group A) or phenoxy (Group I)—has enough time to fully move through the plant, but not enough time to take full effect, which would cause the plant to limit or shutdown photosynthesis and so reduce the efficacy of the bipyridyl application.

The speed of translocation for various chemical products varies, as does the uptake rate of different plants. Plant size also plays a considerable role in how long it takes for a systemic chemical to fully move around the plant. Weather is the final variable which must be considered in the timing puzzle. In warm, damp, lush conditions plants will move a systemic herbicide through their system much quicker than in cold, dry or very hot conditions.

Robust single application of glyphosate after 13 days


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Robust application of glyphosate + paraquat (applied day 7) after 13 days

There is no simple formula to help you decide when to apply a second knock. However, Dr Steve Walker and the rest of the DEEDI weeds team are undertaking extensive research, particularly on feathertop Rhodes, to better predict ideal application timing.

Current general rules of thumb for the second knock timing are:• For feathertop Rhodes, when the first knock is: – glyphosate (Group M): 6 to 8 days after initial application – haloxyfop (Group A): 3 to 7 days after initial application.

• For fleabane, when the first knock is: – glyphosate (Group M): 6 to14 days after initial

application – phenoxy (Group I): 6 to 14 days after initial application.

Please remember that these are only guidelines. The size, age and health of the plant and the growing conditions will help determine where in that range to apply. The key message is: assess your situation and time applications appropriately.

Target size and control expectationsAs many growers will attest, once feathertop Rhodes (or fleabane) reaches maturity it is almost impossible to completely control using single knock chemical practices alone. Unfortunately feathertop Rhodes is very difficult to control, even when using practices such as double knocks with robust rates of haloxyfop (Group A) followed by a robust bipyridyl (Group L) application, as is now allowed under permit, prior to planting mungbeans.

Using this combination on large mature plants and expecting complete control is not only unrealistic but highly risky, as it will cause plants to develop resistance to Group A products more quickly, should any of the surviving plants produce viable seed.

The smaller the target plants the greater the chance you have of achieving 100% control using double knock applications, and the cheaper it will be. If the majority of weeds can be targeted at seedling to pre-tillering stages, then a robust rate of glyphosate followed by a paraquat treatment 6 to 8 days later can be very effective and cost-effective. If there is only a small amount of other plant residue in the field at the time, consider adding a Group K

or Group C herbicide (please check label requirements for various scenarios) to your second knock as a residual to give you longer lasting control during fallow or into your next crop.

In summaryBipyridyl products in a double knock scenario are not the silver bullet many growers are looking for when it comes to the management of feathertop Rhodes or fleabane. However, when used as part of a well thought out management plan, using rotations and crop competition along with knockdown and residual products, bipyridyls do offer a lot of extra flexibility and extra efficacy to our current list of registered knockdown herbicides.

As a single application product, bipyridyls can be quite effective in controlling small to medium seedlings. At the other end of the growing spectrum, they can be quite effective as a rapid desiccant to reduce biomass, halt seed set and allow for tillage or burning events to occur before the plant recovers.

But it is within the context of a planned double knock application that bipyridyls really begin to become an effective tool. Many experts in the use of bipyridyls indicate that they can enhance control somewhere between 10% to 30% over what a single knock systemic application would have achieved.

AcknowledgmentsI would like to say a huge thank you to the experts who contributed their time, thoughts and experience to help me write this article. Without their valuable contributions and input this article would not have been possible. Thank you to:

• Chris Preston, Associate Professor, Weed Management, School of Agriculture, Food and Wine, The University of Adelaide

• Frank Taylor, Research and Development Officer, Nufarm Australia Limited

• Jason Sabeeney, Solutions Development Manager, Syngenta

• Laurie Price, Research Manager, Northern Grower Alliance

•Mark Congreve, Senior Consultant, ICAN•Michael Widderick, Senior Research Scientist (Weeds),

DEEDI• Steve Walker, Associate Professor, The University of

Queensland, Queensland Alliance for Agriculture and Food Innovation (QAAFI)

• Vikki Osten, former Principal Research Scientist (Weeds), Weed Sciences Team Leader, DEEDI.


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Hitting the target—tips from Bill Gordon on optimising Group L applicationDarren Aisthorpe, Extension Agronomist, CQ Grower Solutions, DEEDI, Biloela

Bill Gordon is a widely recognised and respected expert in the field of spray application. In this article Bill shares some of his knowledge and trial data to assist growers to get the most out of their Group L applications.

Understanding how herbicide products will work on your weed target is essential in optimising the efficacy of your Group L applications. Equally, getting as much active ingredient to the target is just as important in the efficacy equation.

‘For products with minimal translocation (ability to move within the plant), like the Group L bipyridyl family of herbicides, we need to place the droplets on all parts of the plant to maximise the level of control,’ Bill says.

‘The coverage on the plant is influenced by the droplet size and the number of droplets. Smaller droplets result in more droplets being produced for each litre of spray that is applied. However, smaller droplets are also more susceptible to factors like evaporation, and can struggle to penetrate large or dense targets.

‘Often the suggested droplet size on the label of older Group L products is a medium spectrum; however, recent trials have shown that coarse and even extremely coarse droplets delivered by an air inducted twin nozzle (AITTJ60®), or by alternating TTI® nozzles forwards and backwards can provide excellent control where adequate water volumes are used (typically around 70 L/ha).’

‘When using a coarse (C) or larger spray quality, you will always produce a lower number of droplets, so they

must be placed correctly on the target. Twin nozzles and alternating angled nozzles have outperformed standard air induction nozzles that deliver the spray directly downwards at volumes of around 70 L/ha,’ Bill states.

This can be seen in the graph, where the performance of the 025 and 015 Teejet® AIXR® nozzles level of control is reduced by 7% to 8% compared to the other angled or twin jet designs. When asked what nozzle style would optimise coverage on plants, Bill responded, ‘I believe the AITTJ® at 50 cm nozzle spacing (3–4 bar) for low drift risk or TTI® 015 (4 bar or higher) with alternating jets at 25 cm nozzle spacings in areas where drift is of concern’.

The following graph and table detail the results of research conducted in April last year by Bill on canary seedling at 4–6 leaf stage. The aim of the trial was to compare the efficacy of different droplet spectrums, nozzle spacings and nozzle styles.

Speed and coverageMost set-ups mentioned have been tested at speeds up to 22 km/h. At higher speeds, coverage is likely to be compromised on larger or dense targets, as most of the droplets will impact on one side of the plant. However, twin jet nozzles may give better coverage than single jets if the speed is 22 km/h or less.

When asked whether operators who frequently spray at speeds in excess of 22 km/hr can maintain coverage by using larger nozzles and higher water rates instead of

Level of control achieved with different nozzle styles and configurations

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Level of control across the whole plot of canary seed (4-6 tillers) from two trials

Trial 1–Sprayseed® @ 0.8 L/ha (14 DAT) LSD 5% 1.8

Trial 2–Roundup® Dual Salt @ 1L/ha (15 DAT) LSD 5% 6.4

April 2011, Kalkee, Victoria


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slowing down, Bill’s response was ‘Yes, provided they didn’t travel faster than 25 km/h.’

‘Timing is perhaps the most critical part of the spray job, so taking longer doesn’t always mean a better job. When choosing a different or larger nozzle, ensure that adequate pressure is achieved at the nozzle for both your average speed and your minimum speed.

‘Make sure that you know what spray quality your nozzle is producing at your average speed and pressure, and at what minimum pressure to set the controller when using Group L products.’

• For high pressure air induction nozzles (e.g. AI®, INjet® or Turbodrop®) set minimum pressures at 3–4 bar, and operate typically at 5–6 bar; for the TTI® operate above 4 bar to maximise efficacy.

• For low pressure air induction nozzles (e.g. AIXR®, AITTJ®, Minidrift® or Airmix®) set minimum pressures above 2–2.5 bar, and operate at 4–5 bar at your average speed.

Drift and inversion managementBill was quite adamant when it came to application with small droplet spectrums: ‘If you are still using a smaller droplet spectrum (i.e. fine from a small orifice flat fan) spray only during daylight hours to avoid the risk of surface temperature inversion. Wind speed should be between 3 and 15 km/h away from any sensitive areas.’ Fine droplets pose a high risk of drift, so the use of nozzles that create fine droplets is NOT RECOMMENDED.

Surface temperature inversion still remains a risk even with larger droplet spectrums such as C, VC and XC spectrums and even though bipyridyl products are not considered

volatile. Always assess your spraying conditions and operate within standard safe spraying conditions. Monitor for potential inversion conditions regularly, particularly if spraying at night, and try to avoid application at high-risk times of the day such as just on dark or just before sunrise. Ensure that there is a constant breeze blowing; during the day this should be between 3 and 15 km/hr, and at night the wind speed must be above 11 km/h to minimise inversion risk.

Water qualityThe efficacy of Group L herbicides is usually affected by dirty water (high levels of turbidity or clay colloids) from dams and channels. Hardness and salinity is not usually a problem for Group L herbicides, but extremely hard or salty water can affect adjuvant in some formulations.

SummaryAs discussed in the ‘Two hit combo’ article, the key to making a bipyridyl product (Group L) work is getting as many ‘viable’ droplets to the plant as possible. Past practice was to use a contact herbicide, with lots of fine to medium solid droplets from a standard flat fan nozzle. This practice brings a high risk of drift, inversion, evaporation and very limited spray windows.

Time and technology have moved forward; research now indicates that we can extend the spray window and improve our efficacy without compromising capacity to get over the country. The data in this article shows that air induction nozzle technology, when combined with angled spray jets and higher water rates, can now extend spray windows. This means growers can get the job done more quickly with more viable droplets before plants start to stress.

Level of control achieved with different nozzle styles and configurations (data corresponding to graph)

Nozzle Pressure Speed Nozzle spacingDirection of spray jet

Droplet spectrum Sprayseed

®* Roundup® Dual

Salt**

AIXR 025 4 bar 18 km/h 0.5 m Vertical C (VC) 99.3% 90%

TT03 3 bar 19 km/h 0.5 m Forward C 100% 97.7%

TTJ025 4 bar 18 km/h 0.5 m Twin jet C 100% 100%

AITTJ 025 4 bar 18 km/h 0.5 m Twin jet C 98.7% 100%

TTI02 6 bar 18 km/h 0.5 m Backwards XC 98% 98.3%

TTI02 6 bar 18 km/h 0.5 m Forwards XC 98.7% 100%

AIXR 015 3 bar 19 km/h 0.25 m Vertical C (VC) 99.3% 90%

TTI015 4 bar 21 km/h 0.25 m Backwards XC 98.7% 98.3%

TTI015 4 bar 21 km/h 0.25 m Forwards XC 98% 96%

TTI015 4 bar 21 km/h 0.25 m Alternating XC 100% 99.3%

TT02 2 bar 20 km/h 0.25 m Alternating C (M) 97.7% 96.7%

Colours indicate nozzle capacity as per international standard. *LSD 5%: 1.8. **LSD 5%: 6.4.Nozzles used in application experiment (colours/sizes varied)

Air Induction Twinjet® AIXR Teejet® Turbo Teejet Induction® Turbo Teejet® Turbo Twinjet®


9

Double knock in practiceMax Quinlivan, Extension agronomist, CQ Grower Solutions, DEEDI, Emerald

Key messages•The double knock technique, when correctly

implemented, provides significantly higher rates of control compared to a single spray.

•Legally, double knock must be used if haloxyfop (Verdict®) is used in fallow and only used preceding a mungbean planting scenario as per APVMA permit 12941.

•While double knocking with haloxyfop in the first knock provided greater than 95% control of dense patches of large feathertop Rhodes plants, weed control is most effective when the target size is small to early tillering plants.

•High rates of glyphosate did not provide anywhere near the same level of control of feathertop Rhodes plants compared to haloxyfop.

ProblemSpring fallow with a thick stand of 30 cm tall late tillering feathertop Rhodes grass.

BackgroundA field with a high seed bank of feathertop Rhodes grass was tilled after chickpea harvest to control weeds surviving the crop. November storms caused the majority of feathertop Rhodes seeds to germinate, resulting in the development of a dense stand of feathertop Rhodes. As part of the CQ Grower Solutions trial program, this site was selected for a double knock fallow herbicide trial to collect product efficacy data; this will eventually be used to seek registration for the use of selected herbicides on feathertop Rhodes. Significant rain fell during this trial, including almost 175 mm during a storm in late January, and conditions were ideal for feathertop Rhodes to recover from herbicide injury.

What was doneThe first knock was applied on 23 December 2011, followed by the second knock 12 days later on 4 January 2012. Two field walks were held at this site, on 19 January and 16 February, to inspect the results of different double knock treatments.

Glyphosate (Group M), haloxyfop (Group A) and quizalofop (Group A) were trialled at three rates, including a target rate (for registration), along with comparison rates above and below. Paraquat was applied in the second knock with one of five residual herbicide treatments. Given the extensive ground cover present at herbicide application, the rationale for including the residuals was to test for additive or synergistic effects of these chemicals on the efficacy of paraquat.

The site was inspected for brownout of leaf material, plant death and weed recovery on 4 January, 13 January and 10 February.

ResultsNote: the results presented are only valid for one site in one season and have not been validated under different conditions or situations.

Twelve days after the first knock (i.e. when the second knock was applied), insufficient time had passed for any of the treatments to have been successful; no treatment showed satisfactory levels of brown out.

Nine days after the second knock (21 days after the first knock), no glyphosate (Group M) treatment had produced satisfactory rates of brown out. Quizalofop (Group A) and haloxyfop (Group A) both showed high rates of brownout (greater than 90%) and appeared well placed to achieve a high kill on feathertop Rhodes. At this stage, treatments without the second spray had all failed to achieve satisfactory levels of brownout.

Fifteen days after the second knock (27 days after the first knock), feathertop Rhodes plants in all glyphosate treatment plots had started recovering from injury, indicating that these sprays had failed. The data suggested that, at best, the high rate of glyphosate might assist in reducing seed set. In haloxyfop and quizalofop treated plots, maximum control of weeds (brownout greater than 95%) was achieved after 9 days. This high level of control was maintained in the haloxyfop plots, whereas in the quizalofop plots efficacy appeared to decline after about three weeks as indicated by regrowth in the affected plants.

Difference between single (left) and double knock (right) applications after 63 Days

At 37 days after the second knock (49 days after the first knock), all glyphosate treatments had failed. The highest glyphosate rate could only achieve 20% to 30% control. In this trial the target rate of haloxyfop (300ml/ha Verdict®) achieved excellent control (95% to 98%) on feathertop Rhodes, whereas the higher comparison rate did not significantly improve control further. Low rates of haloxyfop (150ml/ha Verdict®) had the odd plant starting to recover and was not as successful as the target rate.

While haloxyfop generally provided better control than similar rates of quizalofop, both chemicals had a major impact on the future seed bank.

While haloxyfop generally provided better control than similar rates of quizalofop, both chemicals had a major impact on the future seed bank.


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Central Queensland NVT trials 2011Peter Keys, Principal Technical Officer, DEEDI, Biloela Douglas Lush, Research Scientist, DEEDI, LRC, Toowoomba Don Baills, Scientific Assistant, DEEDI, LRC, Toowoomba

BackgroundThe Grains Research and Development Corporation (GRDC) established the National Variety Trial (NVT) program in 2005 to independently evaluate new varieties of winter cereals and selected pulse crops from all public and private breeding programs prior to their commercial release and make information freely available to Australian grain growers.

In 2010, Agri-Science Queensland, DEEDI, was selected to conduct the NVT program in Queensland.

CQ NVTFor the second consecutive year, all proposed NVT trials were successfully sown at the recommended planting times. All trials were successfully harvested except for the Capella chickpea trial, which was abandoned due to severe hail damage.

NVT Cropwalk at Darren Jensen’s property in September 2011

CQ seasonAll trials were sown into sites with full soil moisture profiles. The CQ season was a typical cold, dry winter. Only minimal rain (10 to 15 mm) was recorded in the June–July period, but this was sufficient to establish winter cereal secondary roots at all sites. The very cold winter delayed flowering of winter cereals by a week or so. Good rain fell at flowering and grain fill periods, which ensured good yields.

Wheat grain proteins were very low (range 8% to 10%) at four of the five sites. This was due to waterlogging and denitrification caused by the extraordinarily prolonged wet summer. Floodwaters lay on the Duaringa site during the summer wet for six weeks and this significantly affected yield and protein.

Trial results for commercial varieties are presented in Tables 1 to 6.

It should be remembered that this report covers the performance of varieties in trials in the 2011 season, which was characterised as a cold winter with little in-crop rainfall until August. Varieties may perform differently in other years. It is important to remember that multi-year, multi-environmental trials (MET) offer the most reliable prediction of a variety’s yield performance.

This information can be found on the NVT website . On the home page, click on Varieties > Variety performance. Predicted yields presented in Tables 1 and 2 of this report are the best way to evaluate a wheat variety’s performance in CQ.

WheatDespite the lack of soil nitrogen, all wheat trials were very uniform and had very acceptable coefficients of variation (CVs) that ranged from 3% to 7%; CVs are a measure of trial accuracy.

EGA Gregory was the best performing wheat overall in both early and main season trials, consistent with the 2010 results when it also topped the trial series. In 16 trials conducted in CQ from 2005 to 2011, EGA Gregory has had the highest predicted yield.

Early season variety EGA Bounty again performed well, repeating the good yield it gave in 2010. Strzelecki gave above average yields in the early trial series, 3% above the site mean yield overall, but yielded below average at Kilcummin.

Some shattering was observed in Baxter and EGA Burke at Capella, Springton and particularly Duaringa. This may have had some affect on yields.

AGT variety Sunguard (code name SUN440H) is a new release. Sunguard has a quality classification of AH and has maturity slightly slower than Baxter. Sunguard gave below average yields overall in both the early and main series. However, it was ranked fourth in the early planted Kilcummin trial.

Sunvale and Sunvex again gave poor yields.

Ventura gave the highest yields of main season varieties. Of the recently released varieties, Spitfire gave above average yields, 5% above the site mean yield overall, outyielding Kennedy by 2%. Crusader and Livingston gave poor yields. These are very quick maturing varieties and may not have been able to respond to the late August rains as well as the slower maturing varieties.

Developed by AGT, Elmore CL Plus (code name VX4338) is a ‘two-gene’ variety that is tolerant to Intervix® herbicide. It gave above average yields at all sites and yielded 4% above the overall site mean yield. Elmore CL Plus has a default quality classification of APW (a final classification is pending) and maturity similar to Hartog.

www.nvtonline.com.au


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DurumHyperno was the highest yielding variety in the trial series.

Quick maturing varieties Jandaroi and Caparoi, which normally do well in CQ, did not perform in 2011. The three months after planting with only minimal in-crop rainfall obviously affected their yield and the varieties were unable to respond to late rains. However, EGA Bellaroi uncharacteristically gave good yields in 2011. This late maturing variety obviously benefited from the good, late rains.

BarleyHindmarsh topped the trial series and appears to have potential for CQ. Mackay, Grout and Shepherd, which have previously performed well in CQ, all yielded above the site mean yield overall.

ChickpeaAs the Capella site was abandoned due to hail damage, there was only one chickpea NVT site (Springton) in 2011.

In the single 2011 NVT chickpea trial, Kyabra and Moti yielded 112%. Plots of PBA Pistol were grazed by rabbits at an early growth stage; this variety yielded 106%.

PBA Boundary (107%), and PBA HatTrick (92%) are not recommended for CQ. These varieties, which are resistant to ascochyta blight, were released for southern production areas and testing so far indicates there is a yield penalty when growing these in CQ. In addition, it is important that industry continues to only source seed of CQ origin in order to minimise the risk of ascochyta blight.

PBA Pistol

It is important to remember that multi-year, multi-site analyses offer the most reliable prediction of a variety’s yield performance. Yield summaries are available on the NVT website. Previous extensive testing over five years in 17 CQ trials show PBA Pistol has a 3% to 6% yield advantage over Kyabra and Moti.

AcknowledgmentsOur sincere thanks to the following CQ grain growers for making trial sites available on their properties and for their cooperation and assistance during the year: Dave Daniels, Ivan Gowlett, Ken Sullivan, Bruce Donovan, Simon Donovan and Darren Jensen.

Table 1. Main season commercial wheat varieties. Grain yield expressed as a percentage of site mean yield at four NVT sites in Central Queensland in 2011

Variety Maximum quality

classification

Capella Springton Duaringa Biloela Mean MET data 2005 to 2011

(I Gowlett) (K Sullivan) (B Donovan) (D Jensen) Predicted yield (kg/ha)

Number of trials

Impala (C51021) SOFT 112 110 111 113 111 3103 9Ventura AH 107 109 108 111 109 3008 21EGA Gregory APH 118 105 97 107 107 3072 21Hartog APH 110 109 98 107 106 2854 21Spitfire APH 100 107 109 103 105 3017 11EGA Burke APH 110 109 100 100 105 2969 18Elmore CL Plus (VX4338)* APW 110 103 104 101 104 2943 4Kennedy APH 109 100 106 97 103 2879 21Leichhardt AH 110 104 92 104 103 2801 5EGA Hume APH 103 104 104 99 103 2943 14Wallup (VV4978-1) n/a 106 92 108 103 102 2956 9Lang APH 95 99 101 95 98 2863 21Sunguard (SUN440H) AH 93 102 96 98 97 2946 14Sunco APH 92 100 98 96 96 2866 14Baxter APH 102 102 85 96 96 2897 21Crusader APH 96 97 88 98 95 2806 18Livingston AH 73 84 73 100 82 2843 17Mean yield (t/ha) 2.91 4.12 2.25 4.74 3.5 LSD 12 7 13 5 CV % 6.8 4.2 7.4 3.1 Probability


12

Table 2. Early season commercial wheat varieties. Grain yield expressed as a percentage of site mean yield at four NVT sites in Central Queensland in 2011

Variety Maximum quality

classification

Capella Springton Duaringa Biloela Mean MET data 2005 to 2011

(I Gowlett) (K Sullivan) (B Donovan) (D Jensen) Predicted yield (kg/ha)

Number of trials

EGA Gregory APH 112 105 109 109 109 3017 16EGA Bounty AH 111 105 103 105 106 2908 16Strzelecki APH 107 106 99 103 103 2829 13EGA Wills AH 98 97 104 99 100 2812 16EGA Wylie AH 102 97 99 98 99 2810 16Sunguard AH 92 102 101 98 98 2791 8EGA Burke APH 98 94 92 98 95 2832 16Sunvale APH 93 96 94 96 95 2726 16Baxter APH 92 90 71 95 87 2806 16Sunvex APH 87 87 80 89 86 2576 10Mean yield (t/ha) 3.89 3.96 2.22 4.54 4.00 LSD 8 8 9 4 CV % 5.3 4.7 5.4 2.7 Probability


13

Table 5. Barley commercial varieties. Grain yield expressed as a percentage of site mean yield at two NVT sites in Central Queensland in 2011

Variety Biloela Springton Mean

(D Jensen) (K Sullivan)

Hindmarsh 115 102 109Skipper (WI4483) 104 112 108Mackay 102 111 106Grout 106 105 105Shepherd 94 108 101Henley 100 102 101Fathom (WI4446) 103 98 101Grimmett 98 100 99Oxford 96 101 99Gairdner 99 91 95Wimmera (VB0432) 87 99 93Mean yield (t/ha) 3.58 2.92 3.25LSD 6 14 CV % 4 9.5 Probability


14

Case study: Taking on new technologies for improved efficiency and sustainability

Grains Best Management Practices (BMP)

Kerrod and Marjorie Shannen purchased Padua in 1979. They currently farm 1000 ha of the property, growing sorghum and wheat for cash crops, and forage oats and sorghum for their cattle-fattening enterprise. After purchasing Padua, they engaged a share farmer until 1988, when Kerrod took on the full farming role.

Forever on the lookout for information to improve their farming enterprise, Kerrod noticed the Grains BMP program advertised in the local paper and thought that by attending they might be able to learn new farming practices that could improve their current way of farming. They were hungry for information and eager to find ways to cut costs and improve efficiency in their farming endeavours.

With marginal rainfall becoming more common over the last 10 years or so, opportunity cropping has become a necessity for many farmers across the region. With the limited rainfall and the inability to take full advantage of deeper soil moisture with their current planter set-up, the Shannens have noticed consistently poor plant strikes from season to season.

This was one of the main drivers for the family when deciding to upgrade their current farming practices (i.e. full cultivation) to minimum till with the aim to move to zero till in the long run.

By moving to minimum till they will increase their potential to retain more stubble and more soil moisture, which will encourage better crop establishment.

In order to put this plan into action, the Shannens purchased a new ST 820 flexicoil 12.5mt bar equipped with double shot moisture seeking boots as well as a new Gason 1860 Aircart and Gason airseeder kit. With the new equipment, they were able to achieve good plant establishment, which was attributed to the fact that they were able to retain more soil moisture at planting.

Kerrod and Marjorie Shannen

Upon completion of the Grains BMP property design and layout module, Kerrod and Marjorie identified a number of areas in which they could improve the profitability and sustainability of their enterprise. They were successful in applying for funding to support the purchase of a Garman GPS, which assisted the Shannens to precisely map paddock sizes, leading to savings on inputs such as seed, pesticides, fertiliser and diesel. Improved farming efficiency means savings on input costs as well as a reduced potential for excess chemical and fertiliser to enter waterways.

Name: Kerrod and Marjorie ShannenProperty: PaduaLocation: South-west of Springsure,

Central QueenslandSize: 3432 hectares—1000 hectares under

dryland cropping and remainder as grazing land for their cattle-fattening enterprise


15

The double shot moisture seeking boots fitted to the flexicoil bar

To further improve their farming efficiency, the Shannens installed GPS guidance into their Challenger tractor (Ez-steer and Ez-guide). This has allowed them to minimise overlap in the paddock in regard to their planting, fertilising and spraying operations. Marjorie and Kerrod claim that the saving in seed alone has meant the transition was very worthwhile. The first planting of sorghum using the guidance system has shown a reduction of four bags of seed over 500 ha, a saving of $2.08 per ha.

Ez-steer and Ez-guide system

Through the Grains BMP program, the Shannens were able to engage Graham Betts (an on-farm spray consultant) to help identify a number of practical solutions to improve the efficiency of their Hardi Navigator II boom spray. Discussions with Graham led them to purchase a set of ASJ Spray Jets-015 low-drift nozzles. These nozzles produce a coarse droplet and as a result increase the efficacy of the spray application. If used in the right conditions, they reduce the potential for chemical to move off target. They also identified the need for an improved chemical mixing and transfer system, which came in the form of a 150L Mixaide chemical mixing vat. Not only does this system improve the safety and efficiency of chemical handling operations, but it also reduces the potential for spillages to occur. All of these changes are designed to reduce the risk of pesticides moving off farm and into waterways.

The Mixaide chemical mixing and transfer system

Low-drift nozzles

In the future, the Shannens hope to gain a better understanding of their soils and fertiliser requirements and inevitably leave their property in a more secure and productive condition for their family when they retire. Both Kerrod and Marjorie claim that the Grains BMP program would be particularly beneficial for other growers who are unaware of or not currently utilising the new technologies that are available.

For more information about the Grains BMP program visit the website at www.grainsbmp.com.au

www.grainsbmp.com.au


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Upcoming events

Date Location Venue Workshop details

28 March Duaringa Council offices Crop nutrition and integrated pest management

17 April Banana TBC Review workshops (Modules 1–5)

18 April Biloela TBC Review workshops (Modules 1–5)

19 April Wowan TBC Review workshops (Modules 1–5)

Grains BMP contacts

Contact Region Phone

DEEDI Rod Collins Biloela 0428 929 146

Hayley Eames Biloela 0459 813 389

Rob Badmann Biloela 0428 103 109

CHRRUP Vicki Horstman Central Highlands 0427 320 539

Rachel Archbald Northern Highlands/Kilcummin 0428 776 249

DCCA Kim Stringer Callide 0416 208 501

Sara Cue Dawson 0417 938 739

Andrea Beard Taroom/Wandoan 0458 448 669

Three Rivers Kate Wilson Middlemount 0429 992 822

Sam Schottelius Middlemount (07) 4985 7511

FRCC John Rodgers FRCC (07) 4921 0573

Getting back to spraying basicsGraham Betts will be returning to Central Queensland for another round of on-farm visits. For those growers who have started the Grains BMP program and would like Graham to provide them with a one-on-one consultation to improve their spray rig, please get in touch with your nearest field officer to register your interest (contact details below). The on-farm consultation is free of charge to all growers participating in the program, and can be timed to fit in with your schedule. During the on-farm visit Graham will also cover issues such as:

•water quality: pH, hardness, bicarbonates• correct mixing order when using various products• chemical group and mode of action (managing

herbicide resistance)• plumbing of the boom and minimising pressure

differences• getting the best result from your pump• selecting appropriate nozzles for your operating

parameters and commonly used products.

Graham Betts visiting a property near Biloela

In this issueQueen Weedy bows outEditor’s etchingsTwo hit combo—making the secondknock count!Hitting the target—tips from Bill Gordonon optimising Group L applicationDouble knock in practiceCentral Queensland NVT trials 2011Consultant profile: Graham SpackmanCase study: Taking on new technologiesfor improved efficiency andsustainabilityGetting back to spraying basics

cropping central issue 53 - department of agriculture and ......march clermont club, 48 sirius st,...

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