galaup benoit - report - 2014

INTERNSHIP REPORT A2

GALAUP Benoit

Internship site: Rancho Durazno

Country: Colorado, USA

Grader: FLANNERY Bernadette Summer 2014

HOW TO OPTIMIZE THE PRODUCTION

OF ORGANIC PEACHES?

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Ecole d’ingénieurs de Purpan Rancho Durazno

75, voie du T.O.E.C. 3938 G 2/10 Road

BP 57611 Palisade, Colorado Zip: 81526

31076 TOULOUSE CEDEX 3

GALAUP Benoit

HOW TO OPTIMIZE THE ORGANIC

PEACHES PRODUCTION?

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SUMMARY

Rancho Durazno is an organic farm in the western Colorado representative of the organic farming

industry throughout the USA. Located in Palisade, a production basin which produces 75% of the peaches

throughout the Colorado, this farm is specialized for 30 years in organic fruit production especially peaches.

Concerning various aspects, this company is a performant farm and the farmer knew how benefit from the

helpful environment and professional context. Indeed this farm produced organic peaches about 220 000

pounds in 2014 and the Produce’s sales, very fluctuating due to the climate, reached 220 000 US$ in 2013,

which was a bad crop year. Three month as trainee on this farm gave me a way to understand its strengths

and the weaknesses. I saw that some orchards were very old and infected by persistent and hard to

manage diseases, what induces the yield’s decreasing, particularly on one field. On the other hand I saw

some opportunities to make faster and easier some heavy manual tasks in the orchard such as pruning and

thinning. That’s why I wondered how to optimize the organic peaches production on this farm.

First, a new way to work out a strategy to replant old orchards is proposed. This includes the old

orchard destruction, soil management practices such as cover crops, amendments, soil solarization and pH

correction in order to control organically the persistent soilborne pests, which often lead to replant failures

in both organic and conventional commercial orchards. In a second time, the orchard layout is imagined.

The rootstock, varieties and training system choices are explained with the aim of finding a performant

combination of disease unbeneficial conditions and orchard efficiency and profitability. Finally, some

modifications are proposed regarding the orchard management and maintenance. The goal is to find an

easier way to realize manual tasks, with mechanization for example, and to improve the orchard growth

and health, including some persistent pest management practices on established orchards.

Next, this study is discussed by explaining the limits of the propositions and their ability to be

applicable on this farm. Amongst others, two peoples gave me their opinion concerning those propositions.

Dr. Amaya ATUCHA, fruit crop specialist and Greg LITUS, manager of the Western Colorado Research center

were interviewed to complete my study.

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TITTLES

SUMMARY ........................................................................................................................................................... 3

TITTLES ............................................................................................................................................................... 4

ACKNOWLEDGMENTS .................................................................................................................................... 5

ABBREVIATIONS AND CONVERSIONS ....................................................................................................... 6

INTRODUCTION ................................................................................................................................................ 7

THE RANCHO DURAZNO, AN ORGANIC FRUIT FARM IN THE WESTERN COLORADO ............... 8

HOW TO OPTIMIZE THE PRODUCTION OF ORGANIC PEACHES? .................................................. 12

DISCUSSIONS.................................................................................................................................................... 20

CONCLUSION .................................................................................................................................................... 23

BIBLIOGRAPHY ............................................................................................................................................... 23

APPENDIX ......................................................................................................................................................... 26

TABLE OF ILLUSTRATIONS ......................................................................................................................... 34

TABLE OF CONTENTS ................................................................................................................................... 35

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ACKNOWLEDGMENTS

Before presenting this report, I would like warmly thank Thomas CAMERON, who hosted me in USA and on

his farm during three month. This experience gave me a way to discover and understand organic peach

farming in Colorado with different practices and culture. I would like thank Christine WILLEFORD, who was

the supervisor and showed me how to realize the current tasks during my internship in the Rancho

Durazno. Billy taught me a lot concerning organic peach orchard general management practices. Generally,

I would like thank those people, the other worker and WWOOFers, especially Jared Anderson, who often

shared the work with me, to welcome myself on the farm. Finally I want to thank Bernadette FLANNERY to

give me piece of advices for the present report and “L’école d’ingénieurs de PURPAN” to give me the

opportunity to realize this internship.

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ABBREVIATIONS AND CONVERSIONS

Conversions

1 inches = 25, 4 mm

1 pound = 0.454 kg

1 lbs. = 0.454 kg

1 acre = 0.405 ha

1 gallon = 3, 785 liters

1 Foot = 30.48 cm

Fahrenheit = Celsius x 9/5 + 32

1 cubic foot =0.02832 cubic meters

1 mile = 1.609 km

Abbreviations

LLC = Limited Liability Company

CSA = Community Supported Agriculture

USA = United States of America

GMO = Genetically Modified Organism

WCRC = Western Colorado Research Center

USDA = United Sates Department of Agriculture

FM = Farmer’s Market

PPN = Plant Parasite nematode

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INTRODUCTION

The USA, with about 2 million farms and more than 900 million acres in farm is the first exporter of the

worldwide agricultural industry.

Known, for example, for its intensive agriculture or the big production of GMO such as corn or soybean,

which more than 90%1 are GMO, we can wonder what the place of an organic peach farm is.

Indeed, less than 0.5 % farms in the USA are certified organic, furthermore, according to a survey realized in

2011 by the USDA, there are just 182 organic peach producers throughout the United States (USDA NASS,

2011). That’s why we can describe the USA’s organic peach industry as a niche market.

The Colorado State, with more than 17% of its acreage as a crop land area, is an agricultural state. This

industry represented more than 40 billion dollars in 2012. Like in the USA, the organic farming industry is

really tiny: about 0.3% of the state’s farms are certified organic in 2011 and we count just 13 organic

peaches farms in Colorado (USDA NASS Colorado Field Office, 2013) (USDA NASS, 2011).

On the other hand, with a harvest of 12 000 tons of peaches in 2011, Colorado is the 6th peach producer in

the USA, challenged by the first producer: California (713 billion tons).

As the first fruit crop produce in the Colorado, 75% of the peaches throughout the state are grown in a

production basin of peaches: the little town of Palisade, where I decided to realize my internship this

summer.

Indeed, such as a second year student in “L’école d’ingénieurs de Purpan”, I chose to spend twelve weeks in

the western Colorado on an organic fruit farm specialized in peach organic production: The Rancho

Durazno.

1 Peter Whoriskey, Monsanto's dominance draws antitrust inquiry [archive], Washington Post, 29 November 2009

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THE RANCHO DURAZNO, AN ORGANIC FRUIT FARM IN THE WESTERN COLORADO

I. RANCHO DURAZNO

The Rancho Durazno is an original farm of the western Colorado. The perfect climatic situation of Palisade

gave the desire to Thomas Cameron to lead an organic fruit orchard especially in peach organic production.

I.1) Development of the farm

Rancho Durazno, a 30 years old farm, knew how to evolve to become a performant organic peach farm.

I.1.1) History

In 1983, Thomas Cameron created the Rancho Durazno in Palisade.

In 1999, the all orchards were organic, and Thomas knew the first harvest of organic peaches.

From 2004 to 2012, the farm grown organic vegetables but the activity stopped because nobody were

enough free.

I.1.2) The farm and the objectives

As a Limited Liability Company, the Rancho Durazno is driven by Thomas Cameron since the creation. He is

fruit grower in Palisade for 35 years. He’s now 63 years old and

maintains a 40 acres organic orchard.

I.1.3) The plans

The farmer plans to realize some project on his farm such as

breed animals for weed management, stabilize peach production,

keep a simple farm’s management, and in a long run, entrust the

farm to his daughters.

I.2) A favorable environment

Crossed by Colorado River, Palisade is located to the beginning of

Colorado’s plateau, where the context is in favor of the

development of an organic fruit farm such as the Rancho Durazno

I.1.4) An helpful natural environment

The farm is located where the De Beque canyon (see in

orange on Picture 1) opens out, which provides a beneficial

warm air to the orchards throughout the year. The farm is

located close to the Mesa irrigation Canal from the Colorado

River and represents the only irrigation source from April to

October. However, the water is very alkaline.

I.1.5) An ideal dry climate

Although the climate (Graph 1) of the desert Colorado is

perfect for growing fruits, late frost (Erreur ! Source du

renvoi introuvable. shows an average of annual extreme

minimum temperatures) can be a problem and reduce highly

the yields on fruit trees. We can see on Graph 2 the variation

of the yields, the price of the peaches in Colorado and so, on

Graph 1: Monthly climate normals (1981-2010) – Grand Junction Area, CO. (NWFSO, NOASS, 2014)

Picture 1: Geographic localization of the farm in Palisade

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the Farm’s produce sales due to the late frosts in spring time.

I.1.6) Professional and economic context

The town of Palisade is a production basin, which

supplies about 75% of the peaches throughout

Colorado State. Indeed, such as the most important

fruit crop in Colorado, peach growing methods are very

well known and the farmer knew how to collaborate

with a really structured peach industry to improve the

management of his farm (See APPENDIX 1).

I.3) The tools of production

I.1.7) The acreage

The medium size farm is 38 acres big. With 30 acres

on the farm, the principal grown crop is peaches

(Graph 3). Some of the trees on these zones are very old and

generally, the yields are decreasing on block 1. The soil texturing

difference from a field to another doesn’t represent a constraint.

However, the soil salinity is high in this area and, associated to the

high pH of the soils, can be problematic to grow crops.

I.1.8) The shades

Two shades are used to stock equipment on different places (see

APPENDIX 2). Furthermore, there’s four houses distributed on both

areas. Those are rented to the workers. Finally, the packing shade,

shared with other growers, is the most important place regarding

the peach selection, packing and conservation thanks to a cooler.

I.1.9) An old equipment

The old and used material is still performant for the orchard management. But this can be dangerous for

some tasks. On the other hand, the farm owns too much equipment regarding its actual needs due to the

old activity of the farm.

I.4) The farmer, the only fixed employee

The employment of seasonal workers adapted to the needs of the farm is the

solution adopted on the farm to realize the important seasonal on the farm.

I.1.10) A seasonal work

The majority of the tasks on this farm are realized in the spring time and the summer. The WWOOFers,

trainees and Mexicans workers realize the manual interventions in the orchard.

I.1.11) An every year changing crew

Although the farmer needs to teach workers each year, this system let him free to take care of the global

management of the orchard and the sales. Plus, qualified workers are lacking on this farm. The vegetable

activity stopped in 2012 due to that.

0

2

4

6

8

Peaches price (1000 Dollars per ton)

Yield per bearing acre (tons)

Farm's Produce sales (100 000 US$)

Graph 2 : Variation of the peach price and yield in Colorado 2003-2012, and farm’s produce sales. (USDA NASS Colorado Field Office, 2013)

79%

5%

3%

3% 10%

Peaches

Cherries

Plums

Abricots

Fallow

Graph 3: Crop land repartition on Rancho Durazno in 2014

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I.5) The diversified outlets

The produce of sales reached about 220 000 US$ in 2013,

which was a bad crop year due to the frost in spring time.

This produce of sales is generally made thanks to three

different outlets (Graph 4), which give a safety for the

income.

I.1.12) The diversified marketable products

Generally from early July to end September, the commercial

activity follows the harvest concerning the peaches. A peak

yield is observed in early august. Different varieties of fruits

(see detail on APPENDIX 3) are grown to diversify the range, enlarge the marketable

season. Those can be processed in jams, dried fruits, fruitsnacks, and purée (for

breweries) to diversify the offer.

I.1.13) A financial safety researched

Diversify the outlets, as a good way to secure the income, is the strategy adopted by

Thomas Cameron. Moreover, the organic way of production is valorized by the USDA Organic label and

recognized by the different consumers (see below Table 1).

II. THE METHODS OF PRODUCTION

With more than 35 years of experience in peach growing, Thomas Cameron founded efficient, modern and

simple methods to manage his orchards.

I.6) A simple crop management

As a very simple management on this farm, the peach training is divided in three different tasks throughout

the year:

2 A box of peaches weighs approximately 20 pounds.

Kind of consumers Price/box2 Analyze

Farmer’s market

Private individuals 45 US$ Need ripe fresh fruits and diversified products, the market is really far and the sales give not always satisfaction

Food stores One Cooperative in New

Mexico, Two organic food stores

From 36 to 38 US$ regarding

the stores

This way give a possibility to sell the most of the peaches and so is the

principal way to make money

Neighbor consumers and organic

growers

Sales to other organic growers Supplies of peaches for event

Breweries 45 US$

Need very ripe peaches, sales of big quantities of peaches to different

growers to enlarge their produces range

Table 1: Description and analysis of the different market outlets

25%

50%

25%

Sales repartition regarding the outlet

Farmer'smarket

food storeschains

Neiborhoodconsummers

Graph 4: Sales repartition regarding the outlets on Rancho Durazno in 2014

Pruning Thinning Picking

Mid-

Nov

Early-Apr Early-July Mid-Sep

Figure 1: Simple peach orchard management throughout the year

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The trees are manually pruned like open center shape: the quad-V training

(see Figure 2). It is a useful intervention to control the size, optimize the future

yields. The manual thinning consists in decreasing the count of fruits on the

trees and is an indispensable intervention to obtain marketable peaches. The

manual picking is, generally done three times per trees. The fruit ripening is

really fast and different in function of the varieties.

I.7) An efficient orchard maintenance

This maintenance, generally efficient, simple and not time consuming shows

some weaknesses.

The micro sprinklers are the best way to irrigate the orchard but the

assessment of the needs is estimate subjectively. Based on regular soil

samples and leaves analyze, a correct fertilization is done thanks to

organic amendments and foliage spray. On established orchards, the only

weed management is mowing because cover crops grow on alleys and

rows. The available tools in organic production are enough to control most

of the pests but some, such as cytospora canker, nematodes, or virus (see

Picture 2), stay problematic in the orchard.

III. HOW TO OPTIMIZE THE PRODUCTION OF ORGANIC PEACHES?

The farmer plans to replant old orchards to stabilize the decreasing production of organic peaches,

including other varieties to extend the commercial season. The orchard lay out should be though to match

to a simplest management.

During my internship, I observed that some peach orchards were very old and infected by persistent

diseases, what induces the decreasing of the yields. Furthermore, I understood the production period

didn’t match at best to the market. Finally, I saw some opportunities to simplify the manual trees

management on this farm. In this case, we can wonder something:

Problem: HOW TO OPTIMIZE THE ORGANIC PEACHES PRODUCTION?

The tool of production

The crew management

The commercialization

The fruit Production

Stre

ngt

hs Respectful of the

environment

Efficient and organized

The farmer is free to focus on the sales

Low cost of the workers

The diversification safe the income

Efficient

Production of high quality organic fruits

Wea

knes

ses

Old orchard

Old equipment

Teach every year

Need experimented workers

A qualified worker is gone

Big influence of peach production on the income

The diversification of the production

bad influence of the climate on the yields

A lot of time consuming manual interventions

The production is decreasing

Peak yield in early august

Opportunities Threats Increasing the production

Plant different crops or varieties of fruits

Mechanize the production

Persistent diseases: Cytospora canker, nematodes, viruses.

Late frosts in spring time

Picture 2 : Rasp leaf virus symptoms on

cherry tree, infected by nematodes

Figure 2: The four shoots of the Quad-V training; Vision above the tree

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HOW TO OPTIMIZE THE ORGANIC PEACHES PRODUCTION?

IV. CONTEXT OF THE STUDY

I.8) Objectives of the study

Before describing the context of this study, it is important to understand its objectives.

I.1.14) Think a performant replanting strategy

The first goal of this study is to work out an efficient strategy to remove old orchards, prepare land for

planting including performant methods to control organically soilborne pathogens. And, on the other hand,

think about the most efficient orchard lay out including training system choice, variety and rootstock

selection.

I.1.15) Optimize the orchard maintenance and management

The second goal consists in proposing solutions to have a faster realization of the heavy manual tasks on

the orchard (thinning and pruning) and to control the persistent pests in established orchards.

I.9) The production unable to satisfy the demand

I.1.16) Increasing of the demand

Generally in the Colorado state, the demand

follows the production. Both seem to rise up

for the ten last years. We can see on Graph 5

the significant increasing of total and utilized

production. The trees show big crop

production each two years because of their

physiology that’s why a linear curve was built

to show the trend. Moreover, the farmer

thinks the peaches demand continues to

grow for 25 years. Indeed, he explains the

interest of the organic food is growing.

I.1.17) A seasonal drop in production

The twenty different varieties of peaches on

this farm give a way to extend the production

from early in July to Mid-September. But we

can observe two drops in production in 2014

at the very start (from 10 to 25 of July) and at

the end (from 6 to 18 of September) the

harvest (see in red on Graph 6). Those are

due to the low acreage of early and late

maturing varieties such as PF1, PF5,

Glowingstar, O’henri or J.H.Hale.

8000

10000

12000

14000

16000

18000

2003 2005 2007 2009 2011

Ton

s

Years

The Increasing of the demand in Colorado 2003-2012

TotalProduction

Utilzedproduction

Linéaire (TotalProduction)

Linéaire(Utilzedproduction)

Graph 5 : Variation of Total and utilized peach production in Colorado from 2003 to 2012 (USDA NASS Colorado Field Office, 2013)

0100020003000400050006000700080009000

Peach Harvest 2014 (lbs.)

4 Moy. mobile sur pér. (Peach Harvest 2014 (lbs.))

Graph 6: Peach Harvest 2014 shows the drops in production.

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Clay-loam

Very gravelly

loam

I.10) An old production tool

As we explained above, the production system is old. Indeed, many fields in the orchard need to be

replanted:

The red gloves trees on A, C, D section of block 1 are

20 years old, as are the Cresthavens trees on G and H

section. The Lorings trees on block M and N are over

30 years old. Most of the trees on those orchards are

died and the density is very low (see Picture 3).

The G and H section are the worst because of the age

of the trees, the disease infection, soil compaction

and many factors which favor the decreasing of

peaches organic production years with years (see

below).

I.1.18) An old orchard

a) The field

This 2.7 acre yield shows the characteristics of an old orchard in

the western Colorado:

With a 3 % slope, the global topographic situation is adapted to

fruit crops. Indeed, this yield is protected because of its location at

the foot of the mountains and the warm air from the De Beque

Canyon is also helpful. This place is particularly adapted for a

peach orchard because of the beneficial climatic situation (as

explained below). On the other hand, the clay-loamy soil, with a

correct amount in organic material (2.8 %) thanks to the good

orchard management practices, is adapted to peach growing.

However, with alkaline soils and water, the soil’s pH is too high

(7.8) and slow the plant’s growth and development with impacting

the nutrients availability for the roots in the soil (see Figure 3). We

can see many nutrient deficiencies on the leaves. Other

consequences are a susceptibility to different pathogens.

Finally, the soil compaction, which focuses on the alleys, is

due to regular interventions with the tractor in the alley of

the orchard for the past thirty years. This is problematic

because the water drainage is bad so the soil moisture is

important and the tree’s growth is weak with pathogen

susceptibility. Furthermore, this field shows an area in the

center of the field where the soil moisture is important due

to the slope and compaction, so the tree death is greatest.

b) The trees

The variety is on these section is cresthaven. This variety

produced in 2014 from 24 August to 05 September. This

production period seem to be not adapted regarding the market’s demand. Indeed, we explained below

that there’s two drops in production at the very start and to the end of the harvest. Furthermore, the

Figure 3: pH and nutrients availability for the roots in the soil

Picture 3: Old trees and low density orchards on block 1

Picture 4: Field aerial view with topography and soil legend (Mesa County, 2014)

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rootstock named Lovell seems to be susceptible to pathogens damages such as nematodes. Moreover, the

initial density on this orchard is very low (350 trees/acre) and the profitability per acre is not the best

regarding the other orchards with higher density (Until 800

trees/acres on this farm for the last planted orchard).

I.1.19) Replant diseases : Cytospora and nematodes

Furthermore, this old orchard is infected by two persistent pests:

The first, a mushroom known as Cytospora canker, Gummosis or

Leucostoma canker is the most destructive pest in the orchard. This

disease, difficult to control in both organic and conventional because

of not available chemical way of control, infects the bark of the tree,

which one produces gum as a response. This leads to at least the

decreasing of the quality and the yields or, at worst, to the death

of the tree. This disease represents a threat due to its strong ability

to contaminate other trees. The Graph 7, from a Colorado state

university’s publication (Ramesh Pokharel W. C., Cytospora Canker

in Tree Fruit Crops, Fact Sheet No. 2.953, 2013), shows the progression of this fungus in a peach orchard.

The second are tiny, microscopic worms called nematodes, especially Plant Parasitic Nematodes (PPNs),

which are feeding the roots of the tree, by sucking the cell content, disturbing root’s ability to take up

water and minerals and finally decreasing peach quality and/or yields. These weak the trees which are

more susceptible to other pests such as cytospora canker. On the other hand, those are able to transmit

many viruses such as Rasp Leave Virus on cherry trees (as observed in the orchard: see above). Moreover,

symptoms caused by these parasitic are difficult to recognize. As I observed

on this field, the infected trees show generally poor growth and chlorosis

symptoms, the roots are damaged too. According to a Colorado state

university’s publication (Ramesh Pokharel C. S., 2011), many species of this

pathogen could be problematic in Colorado’s peach orchards. But Dagger

nematode, Root-lesion nematode (see Picture 5), and Ring nematode are

described as serious in fruit crops in Colorado, especially peach trees. These

are well known to be a major cause of orchard replant failures in both

conventional and organic orchards.

Those two pests are strong to manage and will in a long run, if not

controlled, cause economic losses because of their ability to infect other orchards and destroy young

plantations. We will detail later some pest

management methods.

I.1.20) The decreasing of the fruit production

Those factors induce undeniably, quality and yield

decreasing on G and H section. Graph 8 shows this

reduction on the last six harvests. So the profitability

per acre is also getting worst. This year was the last

harvest on this field because the orchard profitability

seems to don’t reach the economic profitability

threshold. On the other hand, this data give a way to

ensure this orchard shows the worst yield reduction in comparison with the other low density sections

mentioned above.

Graph 7: Increase in the incidences of Cytospora canker in a grower’s orchard where 700 peach trees were planted in a year (Ramesh Pokharel W. C., Cytospora Canker in Tree Fruit Crops, Fact Sheet No. 2.953, 2013)

Picture 5: Root lesion nematode, larva and egg (©William Wergin, www.mactode.com)

0

10000

20000

30000

2009 2010 2011 2012 2013 2014

Peach Harverst on G and H (liebs)

Graph 8: Decreasing of peach production on G and H section from 2009 to 2014

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In this context, where peach production on this farm is unable to satisfy the demand on the entire season

and where the production is decreasing because of old infected orchards, the replantation of these old

trees seem to be the best solution to correct some Rancho Durazno’s weaknesses and ensure a sustainable

business on this farm.

V. HOW TO OPTIMIZE THE PRODUCTION TOOL OF ORGANIC TREE FRUIT

GROWING?

Replanting an old orchard is difficult in organic and conventional orchard because of hard to manage soil

replant diseases, which are able to cause many failures in replanting. The methyl bromide utilization for soil

fumigation had been used for several years in conventional commercial orchard throughout the USA to

avoid any risks regarding soilborne pathogens. The farmer used this chemical to replant trees on bloc 4.This

had been forbidden due to its high toxicity and impact on ozone layer. Furthermore, other chemicals can be

used by conventional fruit growers but those are not available for organic growers. So replanting a peach

orchard organically is a very complex syndrome. Indeed, some certified organic fruits growers prefer

fumigate and go through 3 years certification in order to avoid replant problems. (Barney, 2012, p. p.38)

(APPENDIX 5). However, many peoples sustain that some practices

are able to deal with replant problems in organic orcharding. One of

the goals of this study is to assess the efficacy of these organic ways

of control. However, before applying those technics, the first step in

replanting the old orchard is to remove the trees.

I.11) Destruction of the old orchard

The destruction was done in three main steps this year after the

harvest on G and H section:

The first pruning, done with lappers and axes, consists in cutting the

little branches (Picture 6). Those are leaved on the ground to be

grinded by a crusher linked to the tractor. The goal of this

intervention is to return some organic material from the trees to the

soil and make easy the removing of biggest shoots. The disadvantage

is that could increases the risk of infections, especially cytospora

canker due to the conservation of its spores in the wood and the soil.

The goal of the second pruning is to cut the all rest of the trees with

chainsaws in keeping the trunk 50 cm above the soil level. We can

see the result of this operation on Picture 7. This peach wood,

excellent firewood is taken from the field and stored right next the

block 1 to be sold. This wood, often infected by cytospora canker should be

stored in another place, far from the orchards because the spores are able to

go up to a distance of 40 feet (12,2 m) from the site of production and so

infect other trees (Ramesh Pokharel W. C., Cytospora Canker in Tree Fruit

Crops, Fact Sheet No. 2.953, 2013).

During the third step, the tree stump is removed thanks to a backhoe. This is

a good opportunity to observe soil and rootstocks (see Picture 8). The roots

are brown and there are not white feeder roots. This observation confirms

the presence of PPNs in the rhizosphere.

Picture 6: Before (right) and after (left) the first pruning in G and H section of bloc 1

Picture 7: G and H section of bloc 1 after grinding the little branches and cutting the trees

Picture 8: the stump removed from the soil by the backhoe

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I.12) Soil management practices

According to Dr.Amaya Atucha, soil management practices are one of the best ways to control replant

disease problems (see APPENDIX 4).

I.1.21) Soil building

a) Sub Soiler in Cross

Next to destroying the orchard, the first step in preparing the land consists in improving deep soil structure

and drainage in order to create a healthier environment for the next orchard. Indeed, the sub Soiler can

build the soil 50 cm deep. Subsoiling “in cross” means realizing the intervention as perpendicular work. This

intervention gives a way to fight soil compaction and is the best way to remove the old roots. It’s true that

these roots, by their decomposition by micro-organisms such as nematodes, can produce phytotoxines,

which are very toxic for young trees (Edwards, 1998). In order to create beneficial conditions for the next

plantation on this field, this operation should be repeated until there are no more or a few peach roots in

the soil. In a second time, ploughing or discing the soil should be done to build the soil in surface, destroy

the cover crop, so increase organic matter amount, and finally prepare the field in order to sawing a cover

crop.

b) Cover crop

Dr. Amaya Atucha (see APPENDIX 4) explains that keeping the land in cover crop for four or five years is

always advised to reduce soilborne pathogens risks in peach orchard, but some people (as Greg Litus,

WCRC’s manager, see APPENDIX 5) explain this long necessary rotation could be reduced by combining

some methods. Indeed, cover crop such as mustard combined with manure or compost followed by soil

solarization is described as very efficient to control replant disease in peach orchards (Ramesh Pokharel W.

C., Soil Solarization, a potential Solution to Replant Diseases, 2010) (Ramesh Pokharel W. C., Soil

Solarization, an alternative to soil fumigants, fact sheet N° 0.505, 2011). (Utah State University Extension,

Western Colorado research Center, Colorado State University, 2012, p. 40). Cover crops are a current used

solution to build the soil with their roots, improve organic material and fertility, control weeds, and avoid

nitrogen escaping from the soil. We know today that these cover are very useful ways to control replant

disease in organic orchards. Indeed, the cover crop creates a different environment and ecosystem

unbeneficial for the pests and attractive for helpful fauna. They can act as a non-host for pests such as

nematodes and cytospora canker. We know that further oat and especially mustard, marigold and Sudan

grass are antagonists and can reduce harmful nematodes populations by the bioactive compounds present

in their tissue or exuded from their roots (Edwards, 1998, p. 204) (Guerena, 2006) (Utah State University

Extension, Western Colorado research Center, Colorado State University, 2012, p. 40).Some brassica

species are well known to be efficient as green manure to control PPNs. Those species contain in their

tissue some useful molecule called Glucosinolates, which can be processed by soil microorganisms, when

the cover is plowed, in isothiocyanates, a very harmful molecule for PPNs (Utah State University Extension,

Western Colorado research Center, Colorado State University, 2012, p. 40) (Ramesh Pokharel W. C., Soil

Solarization, an alternative to soil fumigants, fact sheet N° 0.505, 2011) (Guerena, 2006). “Domo”, “Forge”,

“Cutlass”, “Humus”, and “Idagold” mustard are known to be the best varieties fur this use due to their high

concentrations of glucosinolates (Guerena, 2006) (Edwards, 1998). Furthermore, 3-4 cover crops can be

grown during the long growing season in western Colorado thanks to the beneficial climate.

To conclude, we can propose to grow cover crops with a mix of mustard, Sudan grass and Luzern during the

two first years for their ability to build, fertilize the soil and fight the persistent pathogens. The third year,

only mustard should be grown early in the growing season in order to realize a biofumigation combined

with compost addition to improve the efficacy of soil solarization during the summer time.

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I.1.22) Manures and amendments

Replanting an orchard is a perfect occasion to correct and improve soil characteristics. This field, with a

medium amount of organic material (2.8%) should be amended with a large amount of compost or manure

in order to improve agronomic qualities such as structure, fertility, and water holding capacity. Those

qualities improve plant growth and therefore increase tolerance to nematodes and cytospora canker

(Edwards, 1998, p. 219). Furthermore, a great amount of organic material favors the development of

beneficial organisms, which can compete or predate PPNs. (Utah State University Extension, Western

Colorado research Center, Colorado State University, 2012) (Edwards, 1998) (U.S.EPA , 1997). The

secondary effects of compost adding are important to note too. Indeed, a toxic effect of the released

nitrogen from the organic material is mentioned (Edwards, 1998, p. 219). On the other hand, adding

manure is a good way to correct high soil pH on this field by bringing, in this case, acidic products. Finally,

some studies shown that manure or compost brought before soil solarization improve the process.

I.1.23) The Soil solarization

Soil solarization is a hydrothermal process that occurs in moist soils covered by plastic tarps and exposed to

direct sunlight. The solar radiations heat the soil beneath the plastic and the temperature raises enough to

strongly weak or suppress pathogenic populations in the treated soil. On the other hand, volatile biotoxic

component are produced, which are toxic for pathogens already weakened by the high temperature. This

process is often described as an efficient way to control replant disease such as nematodes in replanting

peach orchards (U.S. EPA Methyl Bromide Alternative Case study, 1996).It’s true that temperatures

commonly reach 35-60 C° depending on soil type, season, location and other factors. But those

temperatures reached 54 C° with soil incorporation of mustard as green manure preceding the process at

the WCRC (Ramesh Pokharel W. C., Soil Solarization, a potential Solution to Replant Diseases, 2010). This

technic gives a way to combine biofumigation with mustard thanks to its toxic component (as explained

above) and soil solarization. Indeed, the only soil

solarization showed a reduction of nematodes

populations within the top 45 cm (18 inches) of treated

soil (Ramesh R Pokharel, 2010). Graph 9, from a study

realized at the WCRC, right next to the farm, shows the

significant reduction of total PPNs populations in treated

soil in summer. The other advantages of this process are

many: a weed control is provided and a reduction of soil

salinity was observed. The physical, chemical and

biological soil properties are modified during the process,

so the nutrients bioavailability is increased, what is

beneficial to the following young peach trees. Finally, we

can imagine that this process could threat the soil’s

beneficial microorganisms but they quickly recolonize the

treated soil, even, some flourish during the process (Ramesh Pokharel W. C., Soil Solarization, an alternative

to soil fumigants, fact sheet N° 0.505, 2011).

To conclude, a soil solarization on the future planting rows during 4 to 6 week in summer time seems to be

particularly adapted in our case due to the 300 days of sunlight in western Colorado which provides an

efficient control of soilborne disease such as PPNs. The efficacy should be increased by growing mustard as

green manure and amend with compost before. The farmer already owns the machine which allows the lay

out of the plastic layer on the soil. So the costs are reduced and estimated by the U.S EPA between 630 and

700 US$/acre (plastic and labor).

Graph 9: Change in total plant parasitic nematode population from November to March and again June-September in uncovered and covered soils (Ramesh R Pokharel, 2010, p. 53).

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I.1.24) Decrease the pH

The soil pH as potential Hydrogen represents the acidity or the alkalinity of the soil and has a huge

influence on the nutrients availability in the soil for the roots. As we explain sooner, the higher amount of

7.8 gives imperfect nutrients availability in the soil. The best amount is between 6.5 and 7.5. In this case, a

reduction of this pH seems to be important. Indeed, decrease the pH also provides better growing

conditions for young trees, which are more vigorous, not stressed and so show a better resistance to PPNs

and Cytospora Canker. Lowering soil pH can be difficult and expensive, but amend soil with elemental

sulphur, which is a regulated product, is the most effective material for reducing pH. (Edwards, 1998, p.

190) (Barney, 2012, p. 94). The sulphur is broken down by microorganisms in the soil and combines with

water there to form sulphuric acid which then acidifies the alkaline products present in the soil. In loamy

soil with a pH about 8, such as this field, the advised amount of elemental sulfur to bring to the soil to

decrease pH between 6 and 7 is 1568 pounds/acre (Barney, 2012, p. 95). However, the grower should ask

lab to know the good quantity to bring. According to Greg Litus, the amendment should be done regularly

to sustain a good pH (see APPENDIX 5).

I.13) The orchard layout

After removing old trees, preparing the land during three years by following cover crops, amendment

application, soil solarization treatment and pH correction, the time to think about orchard lay out is come.

I.1.25) Choice of the varieties and rootstocks

The farmer wants to plant peaches in order to stabilize the production and keep a simple management of

his farm.

a) Rootstock

According to Dr.Amaya Atucha and Gred Litus from the WCRC, selection of resistant rootstocks is the best

way to deal with replant diseases. We know that new rootstocks perform better than the classical, Lovell,

such as the removed old trees on this field but they are very sensitive to water stress, and so the tree death

can be high the first year following plantation. Indeed, Viking rootstock, experimented in the neighbor

experiment station, seems to be the best regarding the management of replant diseases (see APPENDIX 4

and APPENDIX 5). On the other hand, Greg Litus sustains that some rootstocks such as Flordaguard and

Nemaguard, often decribed as PPNs resistant rootsocks (Utah State University Extension, Western Colorado

research Center, Colorado State University, 2012) (Barney, 2012) (Guerena, 2006) are not really performant

against this pathogen in this area. Even if Guardian, Schwarzmann, Freedom and Nemared rootstocks are

nematode resistant (Guerena, 2006) (Utah State University Extension, Western Colorado research Center,

Colorado State University, 2012), we will focus on Guardian rootstock because of both nematode resistance

and adaptability to perpendicular-V system discussed later, and Viking rootstock experimented at the

WCRC. Those are in high demand and nurseries have a rather long waiting list, so the farmer should order

trees as soon as possible, and expect to have them in two more years.

b) Varieties

The varieties should be chosen in order to complete the observed drop in production (as explained above).

Flaming Fury PF1, Flaming Fury PF5, Risingstar, Newhaven and Regina as early varieties, and O’henri,

J.H.Hale, Elberta, and Glowingstar as late varieties are grown on the farm and perform well. So the choice

of variety for the future orchard should be done with this selection. Early Red haven peaches produced on

the farm should be avoided because they are sensitive to split stones, which is a serious loss. Most of the

newer early varieties such as Flaming Fury PF1 and PF5 are reputed to be less prone to splitting stones

(Edwards, 1998, p. 147).

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I.1.26) An high density system: the perpendicular V training

We know that Perpendicular V (or KAC-V) and Quad V system, largely employed

on this farm are better alternatives for organic peach orchards (Barney, 2012,

pp. 60,61). But some differences are observed between both. Further studies

describe this perpendicular-V training as the best system for commercial

orchards. Indeed, often compared to other systems, perpendicular V is often

reported as the highest and earlier yielding, the higher crop value and profitable

system. Indeed, even if establishment costs are higher due to the number of the

trees, the savings in tree cost comparing with Quad-V system was not enough to

compensate for the greater yields of the

perpendicular-V (Stephen A.Hoying, Terence L.

Robinson Robert L. Anderson, New York fruit

Quarterly, Volume 15, N°4, 2007) (Kevin R. Day,

Theodore M. Dejong, R. Scott Johnson, 2005)

(M. Elena Garcia, 2002) (Barney, 2012, pp.

459,462). The other described advantages of

this high density system are many: the trees

are more uniform in the orchard. The pruning,

training and harvest are easier, what increases

the labor efficiencies. The system is simple and

easily understood by managers and workers

and the production of high-quality and a high

value fruit is ensured (Kevin R. Day, Theodore M.

Dejong, R. Scott Johnson, 2005). The impact on

the yields of tree losses is smaller than on a low

density orchard because of the number of the

trees (M. Elena Garcia, 2002). And concerning pest management, less chemical per acre should be used due

to the less canopy volume (M. Elena Garcia, 2002). Furthermore, this system gives a way to mechanize the

thinning because of its uniformity.

With a generally decreasing fruit production to stabilize quickly, the performant and early yield

perpendicular-V training should be adapted to the farm. The best planting density concerning the net

present value seem to be between 500 and 625 trees/acres regarding the varieties (see in red on Graph

10).

I.14) A simplified orchard management

I.1.27) Faster pruning

This operation should be done easier thanks to performant uniform training system. My experiences on

other farms taught me that electric pruners are faster than manual pruning. The costs are pretty accessible

for a medium orchard such as the Rancho Durazno. Regarding disease management, we know that

cytospora canker is a weak pathogen that cannot invade healthy invade bark. The fungus is established in

tissue wounded by pruning, winter injury, or other. The best way to control this disease is to reduce

infections by disinfecting tools. In order to save time, the visible infected trees should be pruned last. On

the other hand, for Cytospora management, removing diseased limbs combined with other measures help

tremendously to reduce the pressure (Edwards, 1998, p. 112) (see APPENDIX 4). Finally, pruning in late

winter or early spring, in dry conditions, minimize new infection because trees are more susceptible during

winter (British Columbia p.112) (Ramesh Pokharel W. C., Cytospora Canker in Tree Fruit Crops, Fact Sheet

No. 2.953, 2013).

Graph 10: Effect of tree density on profitability (Net present Value $ /Acre) for two peaches and nectarines variety using a Net present Value analysis of profit over a 15 year orchard life (Stephen A.Hoying, Terence L. Robinson Robert L. Anderson, New York fruit Quarterly, Volume 15, N°4, 2007).

Figure 4: Fruiting peach tree demonstrating the two scaffold perpendicular-V system

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I.1.28) Thinning

The thinning should be easier and faster by using hand held string thinner (as

showed on Picture 9). Those can be used for blossom and bud thinning

regarding the different tools. Indeed these tools can reach effectively into

the first foot or two of a peach canopy, what match better to the

perpendicular-V lay out. The low cost is attractive and the operator is able to

adjust the intensity of thinning as needed for each tree (Shane, 2014).

On the other hand some studies showed that spray some oil such as clove

oil, cinnamon oil and stylet oil could be efficient for thinning blossom

organically ( (Harold Larsen, 2012) but these oils seem to be hard to get and

pretty expensive( as explained in APPENDIX 5).

I.15) Cultural calendar

a) Irrigation

We know that fungus and PPNs development is directly linked to high moisture level in the orchard. That’s

why the irrigation should be estimated more rigorously in order to favor best tree growth and health and to

avoid the establishment of pest beneficial environment. Also, proper irrigation is essential to maintaining a

healthy and productive orchard (Utah State University Extension, Western Colorado research Center,

Colorado State University, 2012, p. 153) (Edwards, 1998, p. 219). As explains Greg Litus, the irrigation

should be assessed by using tensiometers or water moisture sensors which give a way to know when the

orchard really needs water. The real needed amount of water can also be approached.

b) Fertilization

The good fertilization management principles on this farm should not be modified because of their

efficiency. Indeed, the need of nutrient is founded thanks to regular soil samples and leaves analyses. Next,

the fertilization can be corrected with compost or granule form of nitrogen.

c) Direct health management

Regarding cytospora canker, there’s not effective organic treatment but scrapping the

canker (see Picture 10) every fall and spring and treat them with either mustard oil

and sulphur combination, or treat them with a copper solution as well is a way to

control disease development but is a very time consuming practice (as explain Dr.

Amaya Atucha, see APPENDIX 4). On the other hand, woodlots next to the orchard

should be removed because they are spores reservoir. Concerning nematodes

management, many botanical nematicides are available for organic growers. “Ditera”,

a biocontrol fungi product is advised by scientists before planting or to foliage of

growing plants. (Ramesh Pokharel C. S., 2011) (Utah State University Extension,

Western Colorado research Center, Colorado State University, 2012) (Guerena, 2006).

d) weed management

Cover cropping on with the mix of species (Sudan grass, Luzern and mustard) detailed in the cover crop

section should be used in order to maintain soil fertility, weed control and health in the orchard. This cover

will be regularly mowed, as currently practiced on the farm. On the other hand, plastic used to solarize the

planting rows can stay on the soil, as mulch during the first years of orchard establishment in order to

minimize manual weeding around the young trees and decrease labor costs (U.S. EPA Methyl Bromide

Alternative Case study, 1996).

Picture 9: « electro flor » hand held thinner from Infanco Company

Picture 10: gum produced in reaction to cytospora canker infection

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DISCUSSIONS

Some aspects of this study show some imprecisions or drawbacks which need to be cleared.

I.16) Not adapted and imprecise data

Soil analyzes which are used to know soil characteristics are realized on the entire bloc 1, what is not

appropriate. The farmer would need to sample and analyze soil on G and H section and ask more precision

regarding soil salinity and the amount of all the micronutrients

I.17) Why replanting this orchard

Replanting this field with peach crop is proposed because that gives a way to think disease management

practices in order to have productive field as soon as possible after removing old orchards. But, with

available crop land on this farm, the farmer could plant peach trees on other fields in order to save money

(with avoiding soil solarization) and let the G and H section in fallow during 5 years, at least. The present

study expects to give a way to make available land after orchard removing as quickly as possible by using

soil managing practices. On the other hand, other crops, such as grapes, or apples could be planted on this

field with the goal to avoid soilborne pathogen infection (specific to peach tree). Experiment at the WCRC

showed that peach following apples work largely better than peach following peach (see APPENDIX 5).

I.18) Disease management practice to perfect

Before establishing a performant strategy to control nematodes, the soil should be sampled and analyzed

by a laboratory in order to identify the nematodes species and quantities in the soil. Nematodes from soil

samples or infected plants must be extracted, identified and counted in order to determine if one or more

nematodes species are causing damages. (Ramesh Pokharel C. S., 2011)

Several studies established intervention threshold regarding the concentration of nematodes populations

in the soil. The risk is to realize an intervention that could be more expensive than don’t fight the

pathogens.

Most of the solutions such as the chemical and mechanical thinning, the spray of mustard oil for Cytospora

canker management still are evaluating and the efficacy of those solutions, although the perspectives are

good, could be not successful in the Rancho Durazno.

I.19) Soil solarization drawbacks

Solarization, by heating the soil decreases the organic matter amount in the soil, the only treatment is not

enough to treat the deep soil and destroy pathogens. Furthermore, no study shows the possibility to

amend soil with elemental sulfur because soil solarization changes the chemical, physical and biological soil

properties.

I.20) Decreasing soil pH

Before thinking a strategy to decrease soil pH, a new soil analyze should be done because of the effect of

soil solarization on biological, chemical and physical soil properties. The value used to advise the quantity of

elemental sulfur to bring comes from the not enough precise soil analyze on the entire block 1 as explained

sooner Furthermore, the described way to decrease soil pH by amending with elemental sulfur could be

expensive, and there’s no way to assess the value of the beneficial returns on the orchards and the yields,

so, an intervention threshold is not known and available. On the other hand, a machine, called sulphur

burner is available to directly acidify the irrigation water, what seems to be better because of the gradually

effect on the orchard. The farmer thinks that could be a good solution but studies or experiences relating

the sulfur burner’s use and describing the costs, pro and cons are lacking.

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I.21) Rootstock

The Viking rootstocks are very water stress sensitive. So, the first year following the plantation, trees

mortality can be high and induce costly second plantations in order to change died trees on the field.

On the other hand, this rootstock is maybe not adapted for the perpendicular-V system because of little

trees, which will need to be hardly pruned to keep the short size.

I.22) High density system drawbacks

The studies which describe perpendicular-V system as well performing are realized in other countries such

as California, Arkansas and New York states where the conditions are different. Indeed, in those areas

peach trees have a pretty short life (about 15 years) regarding Colorado’s peach orchards (more than 30

years), where the quad-V system had been working very well.

Furthermore, the establishment costs are high because of the number of the trees. So the farmers need to

realize a greater investment for orchard establishment. Finally, the fruit size is not always the best regard

the quad-v system or open center systems.

I.23) Mechanical thinning : the string thinner

The efficacy of these tools is still evaluating and a perfect blossom and bud thinning is not ensured. The

crew needs to learn how to master this tool and should, in a first time, perfect this operation with single

hands as usually done.

I.24) Imprecise cost estimation

Finally, most of the general costs of this study are not approached because of the lack of information to

realize precise economic study. The general trends are only estimated thanks to documentation. Estimated

sales, annual cost, and net returns per acre of a representative western Colorado peach orchard are

approached in the conclusion to clear this point.

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CONCLUSION

The Rancho Durazno, an efficient and modern fruit farm in the western Colorado met some difficulties to

correct its weaknesses. Indeed we explained that the production system is old and several orchard need to

be replanted. That’s why I realized a study to work out an efficient strategy to replant organically peach

orchard including persistent pest management. Cover crop, amendments, soil solarization and pH

correction are suggested before plantation. In a second time, we propose some way to make faster some

heavy manual tasks in peach orchard. A new training system is proposed, as a better alternative regarding

the present needs of the farm. On the other hand, some tools were suggested to have a better irrigation

assessment, a faster thinning and pruning. New ways to control persistent disease such as nematodes and

cytospora canker on established orchards are also proposed. The present study is finally discussed in order

to show the drawbacks and weaknesses of this study. It’s true we explain that imprecise economical

estimation was done. So to complete this appreciation, the Graph 11 shows the general economic trend of

a representative peach orchard of Western Colorado. We can see that economical returns should begin 4

years after plantation. This graph does not include cost of soil management practices and planting costs.

Graph 11: Estimated sales, Annual Costs, and net returns per acres for a representative peach orchard in western Colorado (Rod Sharp, Horst Caspari, and Amaya Atucha, 2002)

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BIBLIOGRAPHY

Barney, D. L. (2012). Guide to Growing Organic Orchard Fruits, Market or Home Production, Site and Crop

Selection, Planting Care and Harvesting, Buisiness Basics. Storey.

Edwards, L. (1998). Organic Tree Fruit Management. Keremeos, B.C. Canada: Certified Organic Associations

of British Columbia.

Guerena, M. (2006). Nematodes : Alternative Controls. Retrieved 09 17, 2014, from https://attra.ncat.org:

https://attra.ncat.org/attra-pub/summaries/summary.php?pub=149

Harold Larsen, R. P. (2012). Efficacy of plant and mineral oils, and Tergitol on peach thinning. Grand

Junction: Colorado State Uniuversity extension.

Internationnal Biochar Initiative. (2014). Biochar. Retrieved 09 17, 2014, from Biochar-Internationnal:

http://www.biochar-international.org/biochar

Kevin R. Day, Theodore M. Dejong, R. Scott Johnson. (2005, April-June). Orchard-system configuration

increase efficiency, improve profits in peaches and nectarines. Consulté le October 10, 2014, sur

http://CaliforniaAgriculture.ucop.edu: http://ucanr.edu/datastoreFiles/391-424.pdf

M. Elena Garcia, C. R. (2002). Two-Scaffold Perpendicular V – A New Training System for Arkansas Peach

and Nectarine Orchards. Consulté le October 2014, 10, sur http://www.uaex.edu/:

http://www.uaex.edu/publications/pdf/FSA-6133.pdf

Mesa County, G. D. (2014). Mesa county GIS viewer . Retrieved 10 07, 2014, from

http://gis.mesacounty.us/: http://emap.mesacounty.us/viewer/

NWFSO, NOASS. (2014, March 5). NOW Data - NOAA Online Weather Data. Retrieved 09 17, 2014, from

National Oceanic and Atmospheric Administration, National Weather Service Forecast Office:

http://www.nws.noaa.gov/climate/xmacis.php?wfo=gjt

Palisade Historical Society. (2012). Historic Palisade Coloring Book. Palisade,, 81526, COLORADO.

Ramesh Pokharel, C. S. (2011, 05). Importance of Plant Parasitic Nematodes in Colorado Crops, Fact sheet

N° 2.952. Retrieved 09 17, 2014, from Colorado State University extension:

http://webdoc.agsci.colostate.edu/aes/wcrc/techbulletins/nematodes.pdf

Ramesh Pokharel, W. C. (2010, 12 21). Soil Solarization, a potential Solution to Replant Diseases. Retrieved

09 17, 2014, from Colorado State University extension:

http://www.colostate.edu/programs/wcrc/pubs/research_outreach/Soil%20Solarization%20_final

%201_.pdf

Ramesh Pokharel, W. C. (2011, 02). Soil Solarization, an alternative to soil fumigants, fact sheet N° 0.505.

(C. S. University, Ed.) Retrieved 09 17, 2014, from http://webdoc.agsci.colostate.edu/:

http://webdoc.agsci.colostate.edu/aes/wcrc/techbulletins/soil%20solarization.pdf

Ramesh Pokharel, W. C. (2013, 07). Cytospora Canker in Tree Fruit Crops, Fact Sheet No. 2.953. Retrieved 09

17, 2014, from http://aes-wcrc.agsci.colostate.edu/horticulture/:

http://webdoc.agsci.colostate.edu/aes/wcrc/techbulletins/cytospora%20fact%20sheet-

Pokharel.pdf

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Ramesh R Pokharel, H. J. (2010). Effect on season ans soil solarization on nematode population in western

colorado peach orchard, Colorado State University Agricultural Experiment Station Technical Report

TR08-10.

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Western colorado research center .

Shane, B. (2014, July). The Evolution of Mechanical Blossom Thinnig in Peaches. Western Fruit Grower, pp.

32-33.

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(2007). More Productive and Profitable Peach Planting Systems. Consulté le October 10, 2014, sur

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Peach-Planting-Systems.pdf

Theodore M. DeJong, R. S. (2005, April-June). Research yields size-controlling rootstocks for peach

production . Consulté le October 10, 2014, sur Escholarship, University of California:

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Methyl Bromide in California Orchards. Consulté le October 10, 2014, sur Methyl Bromide Phase

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APPENDIX

Shades

APPENDIX 2: Map of the Farm

APPENDIX 1: Professional relationships of the farm

RANCHO

DURAZNO

SUPPLIERS:

Sierra Gold and Van Well

nurseries

Compost supplier

CROEWORX (advisor)

CONSUMMERS:

Organic growers

ALLFOOD MARKET

La MONTANITA (Coop)

Breweries in Palisade and

Denver

Individual consumers (FM)

OTHERS:

Colorado National

Bank

Palisade’s growers

Ecole d’ingénieurs de

Purpan

WWOOF network

USDA

Laboratories

Workers

FRUIT PROCESSING:

6350’ Natural food

Company in Palisade

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APPENDIX 3: The range of fruit varieties in Rancho Durazno in 2014

Fruit Peach Apricot Plums Cherries

Varieties Glowingstar

Risingstar

Blowingstar

J.H.Hale

Flammin’ Fury PF5

Flammin’ Fury PF1

Glowhaven

Redhaven

Cresthaven

Newhaven

Regina

Bellaire

John boy 1

John Boy 2

June pride

O’henry

Elberta

Suncrest

Angelus

Starfire

Loring

Allstar

Redglobe

Flavortop

Redgold

Pluots

Perfection

Goldstrike

Goldbar

Brittany Gold

Robada

Black amber

Simka

Redheart

Friar

Elephant heart

Empress

Wickson

Bing

Van

Skeena

Ranier

Sweetheart

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APPENDIX 4: Amaya ATUCHA INTERVIEW

Interview3

Name: Amaya ATUCHA

Name of the company: Western Colorado Research Center, Orchard Mesa site

as a branch of the Colorado state University

Address of the company: 3168 B 1/2 Rd, Grand Junction, CO 81503, United-

states

Position occupied: Dr. ATUCHA is an assistant professor in the Horticulture &

Landscape Architecture Department at Colorado State University, and the fruit

crop specialist at Western Colorado Research

Center. Her current research focuses on

soilborne diseases of fruit trees, nutrient

dynamics and soil health in orchards, and

rootstock root dynamics under replant

conditions.

Retranscription of the interview:

“Hello,

My name is Benoit GALAUP, I am a French student in an engineering school of agriculture and agronomy

(http://purpan.fr/en).

I am realizing an internship in an organic peach farm in Palisade: The Rancho Durazno.

I am interested in working out a strategy of replanting an old orchard on this farm, including some organic

pest management (especially Cytospora canker and nematodes) before and after the plantation.

Have you some pieces of advices to give me please?

Your point of view could be beneficial for my work.

Thank you”

Dear Benoit, Peach replant disease is a very complex syndrome, and the best way to deal with it is through a combination of soil management practices and appropriate rootstock selection. The most important one is to avoid replanting right after the previous orchard has been removed. We usually recommend to keep the land fallow, or with a cover crop for 4 to 5 years. I do realize that this is not possible for every growers, because they need all of their land to be in production to have a profitable business. I would definitely recommend to use a cover crop after removing the old orchard to reduce soil pathogen populations even if it is for one season. There has been extensive work done at Washington State University using mustard as a green cover crop to reduce pathogen populations in soil under replant conditions.

3 The interview was by e-mail.

Picture 11: Dr.ATUCHA, fruit crop specialist at WCRC

http://purpan.fr/en

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Choosing the right rootstock may be the most important strategy to successfully deal with replant disease. There's no replant resistant rootstock for peaches, however there are some new rootstock that have shown to perform better under replant condition than the traditional rootstock such as Lovell. Some of these new rootstocks are hybrids of almond X peach, such as Viking and Atlas. They are in high demands and nurseries have a rather long waiting list, so if you are interested in using these rootstocks you should order trees as soon as possible, and expect to have them in 2 more years. One of the problems with these new rootstocks is that they are extremely sensitive to water stress, thus there tends to be a high mortality of trees after planting them. We currently have an organic replant trial at the research station where we are testing the use of mustard as a green cover crop prior to planting, and Viking rootstock, which seems to be more tolerant of replant disease. You are welcome to visit any time. Regarding cytospora canker, we don't have an organic treatment that has shown to be effective at controlling this fungus. Our management approach for the organic blocks we have at the station, consists of scrapping the cankers every fall and spring, and treat them with either mustard oil and sulphur combination, or we have treated them with a copper solution as well (very time consuming practice). We are still evaluating the efficacy of these two treatments. However, we have noticed that scrapping the canker periodically, and removing diseased limbs and trees has helped tremendously in reducing the pressure of the disease. Good luck with you internship and say hi to Tom. Best, Amaya

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APPENDIX 5: Greg LITUS interview

Interview

Name: Greg LITUS

Name of the company: Western Colorado Research Center, Orchard Mesa site

as a branch of the Colorado state University

Address of the company: 3168 B 1/2 Rd, Grand Junction, CO 81503, United-

states

Position occupied: Manager of the research

center

Signature:

Retranscription of the interview/visit:

The orchard mesa site of the western Colorado research center is one of the best places to understand how

to manage and optimize a peach orchard in the area. Researchers are experimenting right now with how

to manage peach replant diseases such as nematodes. The mesa site is close to the Rancho Durazno (about

10 miles), so the similar environment gives a way to make sure that the potential solutions founded in the

mesa site should be applicable on the farm.

“My name is Benoit GALAUP, I’m a French student in agriculture and agronomy engineering school and I am

realizing an internship on an organic peach farm in Palisade: the Rancho Durazno

I come here because I try to work out a strategy to replant an old orchard on the farm including replant

problem management such as nematodes. And on the other hand, I am thinking how to optimize the

management of the peach organic orchards on the farm. I have read a lot of the publications from the

western Colorado research center and I am looking for some precisions

So, first, would you like introduce your work at the research center please?

Sure, here is a 3 years old experiment peach organic orchard bloc, the previous crop are peach trees

(Picture 13). The replant diseases are very difficult to

manage in organic productions and some organic orchardists

prefer use conventional methods such as soil fumigants and

come back later to organic way of production. Despite this,

the best way to fight against nematodes is an appropriate

resistant rootstock selection. On the site, we tested and we

adopted new rootstocks such as hybrids of almond X peach,

called Viking.

Indeed, these rootstocks seem to be resistant to replant

disease problems in peaches such as nematodes but they are

very susceptible to moisture and water stress (Picture 14).

So, the losses the year of the plantation can be high.

Picture 13: Three years old organic peach orchard replanted with another peach orchard as a preceding crop in Orchard Mesa site at the WCRC.

Picture 12: Greg LITUS, manager of the Orchard Mesa site of the WCRC

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Furthermore, it is pretty difficult to have those rootstocks because of the strong demand by the peach

orchardists.

I saw on certain documentation that Nemaguard or

Flordaguard rootstocks are nematodes resistant, do you think

those could be useful to deal with replant disease?

No, we found that those rootstocks were not really nematodes

rootstocks in the area. Maybe they’re in another country with

different environment.

I’m interested in the management of Cytospora canker on an

organic peach orchard, I have read on factsheets from WCRC

that mustard oil, combined with other practices could help to reduce the pressure of the disease in the

orchard. Could you tell me about that?

Cytospora canker is a very complex disease. We can find this disease throughout the world and it’s not very

well known in Colorado. The control of this pest must be done with many factors. First, bring the right

amount of water to the trees with an appropriate irrigation system is an important way to decrease air

moisture in the orchard and so reduce the infection of the mushroom.

Next, the grower should avoid any stresses, which give more susceptible trees. This stress can be caused by

irrigation, poor soil healthy and fertility, poor agricultural practices, or some virus infection. Indeed, healthy

and well growing trees are more resistant to the disease.

And finally, as direct management practices, we remove the infected shoots, we scratch the gum produce

by the tree in reaction of the canker infection, and finally we treat with some oils, such as clove oil,

cinnamon oil and mustard oil. These could be efficient to reduce the incidence of the disease. But this only

way to fight is not enough, the oil are expensive, hard to get, and we don’t know when to spray and which

concentration is the best to fight the disease with a lower costs.

Well, concerning the irrigation, I saw on factsheets that drip irrigation system is advised to reduce the

incidence and development of Cytospora canker in the orchards. But in this case, the cover crop is not

irrigated. So, drip irrigation is not a good solution to fight against the disease?

You’re right. The drip irrigation could be helpful when there’s no cover in the alley. For organic growers

who chose to keep a cover crop between the rows, I think that micro sprinkler irrigation is the best

intermediate, even if the bark of the tree is wet.

Ok. And regarding replant disease management, I saw some studies realized in the WCRC, where

solarization, previously associated with poultry manure and

mustard cover crop, had been described like very efficient

to deal with replant diseases in peach orchard, such as

nematodes. What do you think about that?

Soil solarization is only practicable with a clear plastic in

summer time when the amount of sunlight is the best. Soil

temperatures can reach about 122 F° (50 C°) on the top. Soil

solarization as a great effect on the top of the treated soil

but its effects is not deep enough for replanting orchard.

This process is really useful for growing vegetables. I just

would say that soil solarization is one of the many ways to Picture 15: Three years old organic peach orchard replanted with apple orchard as a preceding crop in Orchard Mesa site at the WCRC.

Picture 14: dead tree with moisture susceptible Viking rootstock

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deal with replant problems in peach orchard.

What do you think about mustard cover crop before and after the plantation to reduce risks of nematodes

infection in the orchard?

I think that’s one of the potential solutions, this is how we do on the organic peach orchard experiment

block to contribute to the management of nematodes. Mustard covers are rich in glucosinolates. These

components, mixed to the soil when the cover is destroyed are digested by the microorganisms to create

molecules called isothionates, very toxic for nematodes.

On the other hand, we experiment with the biochar. This is a coal form processed from wood. This process

produces fuel or electricity too and represents a way to fix very sustainably the carbon in the soils, maybe

about thousand years. That could be an efficient way to reduce the global warming effect. Indeed, the fixed

carbon cannot escape as greenhouse gases in the atmosphere. In our case, this could help to deal with

nematodes problems if brought in the soil before planting, due to its capacity to host micro-organisms in

the pores in the coal. And also, sustain beneficial organisms which compete plant parasitic nematodes.

Interesting! And to summarize, what would you advice to an organic grower to deal with soilborne

diseases?

The organic grower should do everything possible! Before planting, the best could be to combine

appropriate rootstock selection, growing cover crops such as mustard, solarization treatment, bring

amendments and composts to favor the diversity of microorganisms. The farmer can consider open the

future planting raw with a backhoe and solarize the deep soil to improve the efficacy of the process. After

planting the water and nutrient management should be the more rigorous as possible.

Ok. Concerning the irrigation of the orchard, what do you think about using measurement tools such as

tensiometers?

Tensiometers or water moisture sensors are an excellent way to have a clear idea of the needs of the

orchard. They are very useful to bring an appropriate amount of water and so reduce risk of nematode and

cytospora infection and development. Furthermore, those can automatic by connecting to a computer.

Ok. According to the look of those different fields (see Picture 13 and Picture 15), the best way to deal with

replant disease could be to avoid following peaches with peaches?

You’re right. We can easily see the difference on those trials. The best solution could be to make a rotation

with different fruit crops. The problem is that most of peach growers are specialized in peach production

and need their entire field in production to have a profitable business.

Well. I am thinking about work out a replant strategy with high density systems. I saw that Perpendicular V

system could be better than quad V system for growing peaches. What’s your opinion?

That’s difficult to say one is better than the other. The difference is close. With perpendicular V, the costs

of planting are high because of the number of the trees. But on the other hand, the production is sooner in

orchard’s life. I think perpendicular V should be easier regarding the orchard management.

Do you think varieties could be a way to control pests in organic peach orchards?

Directly not because the peach varieties don’t show a specific resistance to pathogens but combining

different varieties in an orchard could be a good way to slow disease development.

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I was interested in thinking about new ways to make easy the heavy manual tasks in the orchard such as

thinning. I saw on a study that some oils as you were talking about sooner were able to thin efficiently the

trees. And maybe, combined with mechanical thinning, those could be useful ?

That’s a good idea but those oils can damage the trees, so it’s important to find the good concentration.

This topic is on research at the WCRC. However, mechanical thinning such as string thinners can be used

and have good results for thinning buds.

My last question is about decreasing soil’s pH. I know a farmer is able to do that thanks to sulfur

component amendments, which can acidify the alkaline part of the soil, such as calcium. What do you know

about that?

Decreasing the pH have a good effect on the orchard and can be done thanks to elemental sulfur

amendments or by treating with sulfur the water for the irrigation. A few people do that in the area. The

amendment should be brought every year due to the alkaline soil and water in western Colorado.

Well, thank you very much for introducing yourself and the research center. That was really interesting!

You’re welcome! Feel free to visit us any time!

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TABLE OF ILLUSTRATIONS

Graphs:

Graph 1: Monthly climate normals (1981-2010) – Grand Junction Area, CO. (NWFSO, NOASS, 2014) _______________ 8

Graph 2 : Variation of the peach price and yield in Colorado 2003-2012, and farm’s produce sales. (USDA NASS

Colorado Field Office, 2013) _________________________________________________________________________ 9

Graph 3: Crop land repartition on Rancho Durazno in 2014 ________________________________________________ 9

Graph 4: Sales repartition regarding the outlets on Rancho Durazno in 2014 _________________________________ 10

Graph 5 : Variation of Total and utilized peach production in Colorado from 2003 to 2012 (USDA NASS Colorado Field

Office, 2013) ____________________________________________________________________________________ 12

Graph 6: Peach Harvest 2014 shows the drops in production. _____________________________________________ 12

Graph 7: Increase in the incidences of Cytospora canker in a grower’s orchard where 700 peach trees were planted in a

year (Ramesh Pokharel W. C., Cytospora Canker in Tree Fruit Crops, Fact Sheet No. 2.953, 2013) _________________ 14

Graph 8: Decreasing of peach production on G and H section from 2009 to 2014 ______________________________ 14

Graph 9: Change in total plant parasitic nematode population from November to March and again June-September in

uncovered and covered soils (Ramesh R Pokharel, 2010, p. 53). ____________________________________________ 17

Graph 10: Effect of tree density on profitability (Net present Value $ /Acre) for two peaches and nectarines variety

using a Net present Value analysis of profit over a 15 year orchard life (Stephen A.Hoying, Terence L. Robinson Robert

L. Anderson, New York fruit Quarterly, Volume 15, N°4, 2007). ____________________________________________ 19

Graph 11: Estimated sales, Annual Costs, and net returns per acres for a representative peach orchard in western

Colorado (Rod Sharp, Horst Caspari, and Amaya Atucha, 2002) ____________________________________________ 23

Pictures:

Picture 1: Geographic localization of the farm in Palisade _________________________________________________ 8

Picture 2 : Rasp leaf virus symptoms on cherry tree, infected by nematodes __________________________________ 11

Picture 3: Old trees and low density orchards on block 1 _________________________________________________ 13

Picture 4: Field aerial view with topography and soil legend (Mesa County, 2014) _____________________________ 13

Picture 5: Root lesion nematode, larva and egg (©William Wergin, www.mactode.com) _______________________ 14

Picture 6: Before (right) and after (left) the first pruning in G and H section of bloc 1 ___________________________ 15

Picture 7: G and H section of bloc 1 after grinding the little branches and cutting the trees ______________________ 15

Picture 8: the stump removed from the soil by the backhoe _______________________________________________ 15

Picture 9: « electro flor » hand held thinner from Infanco Company ________________________________________ 20

Picture 10: gum produced in reaction to cytospora canker infection ________________________________________ 20

Picture 11: Dr.ATUCHA, fruit crop specialist at WCRC ____________________________________________________ 28

Picture 12: Greg LITUS, manager of the Orchard Mesa site of the WCRC _____________________________________ 30

Picture 13: Three years old organic peach orchard replanted with another peach orchard as a preceding crop in

Orchard Mesa site at the WCRC. _____________________________________________________________________ 30

Picture 14: dead tree with moisture susceptible Viking rootstock ___________________________________________ 31

Picture 15: Three years old organic peach orchard replanted with apple orchard as a preceding crop in Orchard Mesa

site at the WCRC. _________________________________________________________________________________ 31

Appendix:

APPENDIX 1: Professional relationships of the farm _____________________________________________________ 26

APPENDIX 2: Map of the Farm ______________________________________________________________________ 26

APPENDIX 3: The range of fruit varieties in Rancho Durazno in 2014 ________________________________________ 27

APPENDIX 4: Amaya ATUCHA INTERVIEW _____________________________________________________________ 28

APPENDIX 5: Greg LITUS interview ___________________________________________________________________ 30

Figures:

Figure 1: Simple peach orchard management throughout the year _________________________________________ 10

Figure 2: The four shoots of the Quad-V training; Vision above the tree _____________________________________ 11

Figure 3: pH and nutrients availability for the roots in the soil _____________________________________________ 13

Figure 4: Fruiting peach tree demonstrating the two scaffold perpendicular-V system __________________________ 19

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TABLE OF CONTENTS

SUMMARY ...................................................................................................................................................... 3

TITTLES .......................................................................................................................................................... 4

ACKNOWLEDGMENTS ................................................................................................................................ 5

ABBREVIATIONS AND CONVERSIONS .................................................................................................. 6

INTRODUCTION ........................................................................................................................................... 7

THE RANCHO DURAZNO, AN ORGANIC FRUIT FARM IN THE WESTERN COLORADO .......... 8

I. Rancho Durazno ................................................................................................................................................. 8

I.1) Development of the farm .................................................................................................................................. 8

I.1.1) History ........................................................................................................................................................... 8

I.1.2) The farm and the objectives ......................................................................................................................... 8

I.1.3) The plans ....................................................................................................................................................... 8

I.2) A favorable environment .................................................................................................................................. 8

I.1.4) An helpful natural environment ................................................................................................................... 8

I.1.5) An ideal dry climate ...................................................................................................................................... 8

I.1.6) Professional and economic context .............................................................................................................. 9

I.3) The tools of production ..................................................................................................................................... 9

I.1.7) The acreage ................................................................................................................................................... 9

I.1.8) The shades .................................................................................................................................................... 9

I.1.9) An old equipment ......................................................................................................................................... 9

I.4) The farmer, the only fixed employee ................................................................................................................ 9

I.1.10) A seasonal work ........................................................................................................................................ 9

I.1.11) An every year changing crew .................................................................................................................... 9

I.5) The diversified outlets ..................................................................................................................................... 10

I.1.12) The diversified marketable products ...................................................................................................... 10

I.1.13) A financial safety researched.................................................................................................................. 10

II. The methods of Production ...............................................................................................................................10

I.6) A simple crop management ............................................................................................................................ 10

I.7) An efficient orchard maintenance................................................................................................................... 11

III. How to optimize the production of organic Peaches? .......................................................................................11

HOW TO OPTIMIZE THE ORGANIC PEACHES PRODUCTION? ................................................... 12

IV. Context of the study .....................................................................................................................................12

I.8) Objectives of the study ................................................................................................................................... 12

I.1.14) Think a performant replanting strategy ................................................................................................. 12

I.1.15) Optimize the orchard maintenance and management .......................................................................... 12

I.9) The production unable to satisfy the demand ................................................................................................ 12

I.1.16) Increasing of the demand ....................................................................................................................... 12

I.1.17) A seasonal drop in production................................................................................................................ 12

I.10) An old production tool .................................................................................................................................... 13

I.1.18) An old orchard ........................................................................................................................................ 13

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I.1.19) Replant diseases : Cytospora and nematodes ........................................................................................ 14

I.1.20) The decreasing of the fruit production................................................................................................... 14

V. How to optimize the production tool of Organic tree fruit growing? .................................................................15

I.11) Destruction of the old orchard ........................................................................................................................ 15

I.12) Soil management practices ............................................................................................................................. 16

I.1.21) Soil building ............................................................................................................................................ 16

I.1.22) Manures and amendments .................................................................................................................... 17

I.1.23) The Soil solarization ................................................................................................................................ 17

I.1.24) Decrease the pH ..................................................................................................................................... 18

I.13) The orchard layout .......................................................................................................................................... 18

I.1.25) Choice of the varieties and rootstocks ................................................................................................... 18

I.1.26) An high density system: the perpendicular V training ........................................................................... 19

I.14) A simplified orchard management .................................................................................................................. 19

I.1.27) Faster pruning ........................................................................................................................................ 19

I.1.28) Thinning .................................................................................................................................................. 20

I.15) Cultural calendar ............................................................................................................................................. 20

DISCUSSIONS .............................................................................................................................................. 21

I.16) Not adapted and imprecise data ..................................................................................................................... 21

I.17) Why replanting this orchard ........................................................................................................................... 21

I.18) Disease management practice to perfect ....................................................................................................... 21

I.19) Soil solarization drawbacks ............................................................................................................................. 21

I.20) Decreasing soil pH ........................................................................................................................................... 21

I.21) Rootstock ........................................................................................................................................................ 22

I.22) High density system drawbacks ...................................................................................................................... 22

I.23) Mechanical thinning : the string thinner ......................................................................................................... 22

I.24) Imprecise cost estimation ............................................................................................................................... 22

CONCLUSION .............................................................................................................................................. 23

BIBLIOGRAPHY ......................................................................................................................................... 24

APPENDIX ................................................................................................................................................... 26

TABLE OF ILLUSTRATIONS ................................................................................................................... 34

TABLE OF CONTENTS .............................................................................................................................. 35

galaup benoit - report - 2014

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