hortgro science symposium 2016 summary report

7/25/2019 HORTGRO Science symposium 2016 Summary Report

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TECHNICAL

SYMPOSIUM

2016

HORTGRO SCIENCE

SUMMARY REPORT

EFFICIENCY THROUGH

THE VALUE CHAIN


2/23

HORTGRO SCIENCE

www.hortgro-science.co.za

+27 (0)21 882 8470/1

HORTGRO

www.hortgro.co.za

+27 (0)21 870 2900

CONTENTS

Introduction: HORTGRO Science Technical Symposium 2016 Efficiency through

the Value Chain

Cautious Optimism: Politics & Climate Change

Make every drop count: Drought 2016: what does the future hold?

Intelligent Irrigation Key

Technology will never replace a farmer

The rain in Spain stays mainly on the plain Learning from an irrigation expertabout what to do when it doesnt rain in Spain

Dam Building 101

In search of the apple

Not Chilled Enough

Utopian options for nurseries

Tissue culture takes root

Cantankerous Nursery Trees

Biological control: Monitoring mites into oblivion

Optimising spray efficiency

Carbon dioxide (CO) and the story of an apple producers worst nightmare

Playing it safe with DPA

There is life after DPA for Packhams Triumph pear exporters

To Cool or not to cool?

The good, the bad and how to save us from the ugly

CATTS, Vapormate show promise in postharvest pest control

FCM: Full frontal attack needed

Become a Pruning Connoisseur

Photo Page

Sponsors

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We are not here today for the food or for social

services, we are here today for one reasononly and that is to grow our proft and growour businesses. We are partners in the game of

developing this industry. - Pitso Sekhoto

HORTGRO Science Technical Symposium 2016

Eciency through the Value Chain

WITH ve days, 55 speakers, 28 sponsors and exhibitors, and more than711 people attending six events records were yet again shattered at theannual HORTGRO Science Technical Symposium that took place at Alle Bleue,Groot Drakenstein, during the rst week of June this year.

The symposium themed Increasing Eciency along the Value Chain focussedon industry problems, technical challenges, opportunities and new researchin the deciduous fruit industry. This year delegates from as far aeld asBotswana, Limpopo, Mpumalanga, Free State, Eastern Cape and Western Capeattended the event which has its roots in the Cape Pomological Association. Ithas grown into its current format over several decades, changing slightly this

year with two new attachments: a new era grower day and a postharvestday.

This year we decided to consolidate our dierent events into one focussedaction with the objective of growing the symposium into the premium eventof the year. Thereby creating opportunities for growers from other regionsto get the full package from pre-harvest to postharvest, increasing theexposure for exhibitors and sponsors, showcasing our research, broadeningthe attendance and increasing the interaction between the dierent role-players in the deciduous industry, said Hugh Campbell, HORTGRO ScienceGeneral Manager.

NEW ERA

Several role-players, including the Western Cape Governments Departmentof Agriculture, congratulated HORTGRO with the back to basics symposiumthat catered for emerging growers.

Pitso Sekhoto, Free State grower and Deciduous Fruit Development Chamber

(DFDC) Chairman, said that it was a pleasure to be at an agricultural eventand see such a good mix of black and white together. The Chambers goal isto transform the industry and when we mix like this we share experiences,learn and make business.

PICTURE FROM LEFT:PitsoSekhoto (DFDC Chairman), Maritte Kotze(HORTGRO Information Manager), HughCampbell (HORTGRO Science GeneralManager), and Dr Job Mthombeni (Day 1:Session 1 Chair and Limpopo Grower).


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Cautious Optimism: Politics & Climate Change

IN South Africa, good news lurks behind bad news,political analyst Max Du Preez (photo left) told growersand industry players on the opening day of the HORTGROScience technical symposium 2016.Delegates had reason to be cautiously optimistic as Du Preezgave broad insight into the major political and economicissues facing the industry and South Africa at present.He said South Africas greatest asset was that it was stillan open society on the level of big Western democracy.

In the study of failed states an opensociety never becomes a failed state.

Du Preez went on to list several assets which put SA in a favourable position.We do not have tribal, ethnic, or regional conictwe have no terrorism in oursociety we have no religious fundamentalism in our society we have remarkableinfrastructure we have our constitution that is intact our judiciary is independentand functional and our military is apolitical and they serve the government of theday.

Du Preez further said that South Africans were overreacting to the Land ExpropriationBill. We are a constitutional democracy. You cannot make an act in Parliament thatis contrary to the spirit and letter of the constitution, he said. According to Du Preezthe bill might go through the constitutional court where a few denition changeswould be a likely scenario.

It is not bad legislation it is legislation we need, he said. He emphasized that landwas not an agricultural problem, but a political one and that the give our land backnarrative was a myth.

He said only one-third of black South Africans expressed a desire to own agriculturalland. The economic shockwave brought by the 9 December 2015 shuing of nanceministers was a bad day for our economy, but a brilliant day for our democracy,

according to Du Preez.

It brought about the realisation that the economy is real, and if you upset it you will

feel it the next day.

In the study of failed states an opensociety never becomes a failed state.

CLIMATE CHANGE

While Du Preez expressed optimism in terms of South Africas functioning constitutionaldemocracy, climate change experts were more conservative in their assessment ofenvironmental challenges facing the sector in the future.

Prof Roland Schulze from the Centre for Water Resource Research at the Universityof KwaZulu-Natal said that 2015 was the hottest year on record globally, while April2016 was the hottest April on record.

Schulze said that there was an urgent need for localised climate models and thatfarmers needed to consider what they would grow and where.

Push events would see a shift in the timing and geographical range of rainfall andtemperature, while pulse events would reduce days with frost, alter times whenthe critical number of chill units are reached, and cause additional hot days.

Schulze illustrate his argument by comparing the current chill unit situation withwhat it would possibly look like in forty years from now. The implications are thatwe could see a shift in production areas and new varieties being planted.

NOW 40 YEARS FROM NOW

In leaving our carbon footprint everywhere, I hope this is a wake-up call to farmers,researchers, policy-makers and funders alike.

POSSIBLE SIGNS OF CLIMATE CHANGE

More severe storms such as this thunderstormin Durban on 11 December 2009.

More frequent brushres such as these in March2015 in Cape Town.

Global warming cause more intenseEl Nins.

The Western Cape would see warming of between 1.5-3.0C by 2050, according toProfStephanie Midgley from the Department of Horticultural Science at StellenboschUniversity.

According to Midgley growers in the region would experience more hot days, fewercold days, reductions in winter rainfall, and a decrease in positive chill units.


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This could have consequences for fruit growers who would need to plant heat resistantcultivars and use scarce resources, such as water, more eectively.

Midgley said fruit production would remain viable in the Western Cape, but water wasa key issue. In 2015-2016 we saw the worst drought in 30 years, with unnaturallyhigh temperatures, she said. The drought combined with re damage resulted inlosses of R720 million to the wine/fruit industry.

She then highlighted climate shifts in the Western Cape over the past fty yearssuch as rising temperatures (1C warming); a reduction in rainy days from Jan-April and August; an increase in rainy days in Nov-Dec in the west; a shift towardsa later start of the rainy season and a wetter late season; a decrease in positive chillunits. According to Midgley urgent action was needed in the agricultural sector toadapt to the unavoidable impacts of climate change, and reduce its greenhouse gasemissions.

So what can fruit farmers do to adapt?

Midgleys 11-point list:

Better site preparation and soil management Better cultivar and rootstock choices; plant material Ecient training systems and canopy management Better water management Precision farming and ne-scale mapping: Cape Farm Mapper, FruitLook,

drones etc. Shade netting Rest-breaking agents Integrated pest and disease management; understand the importance of bees Risk reduction & management Monitoring and data management Market intelligence: global climate change impacts

She also urged growers to make smart cultivar choices:

Cultivars with lower chill requirements Red/blushed cultivars/strains which are less sensitive to high temperatures Cultivars/strains which are more resilient against sunburn Cultivars/strains with good fruit size distribution Make use of very early or very late cultivars to avoid mid-season climate stress Cultivars with markets for Class 2 and 3 fruit Genetic stability can be compromised under conditions of stress. Great care

should be taken when selecting and propagating red/blushed strains.Resilience to colour loss and sunburn, together with chilling requirement, willbecome ever more important as cultivar criteria.

The quality of plant material will becomea crucial factor, in negotiating the eects of

climate change.

Growers would be wise to use improved robust strains and stay away from old,sensitive ones. Plant healthy certied trees that have healthy root systems and aredisease-free. Remember that poor quality trees are more susceptible to climatestress, she said.

Where water management is concerned Midgley urged growers to: maintainwater infrastructure and reduce water loss; pay attention to drainage and run-omanagement; make sure you manage on-farm wetlands, river banks including alienplant clearing; have a farm drought plan.

Climate change will have dierent impacts in dierent regions, she said. Therefore,building infrastructure is not always the solution. Adaptation must also include more

ecient use and improved catchment management.Midgley concluded that every production manager and technical advisor needs toengage with the following ve fruit business needs:

Knowledge and strategic research Adaptive technologies The business case for adaptation Forward planning Monitoring, analysis and adjustments

To learn more about Midgleys SmartAgri approach for deciduous fruit growing visitwww.greenagri.org.za. Read Midgleys article in the June/July edtion of the SAFruit Journal, pg. 70-72.

PICTURE FROM LEFT:AntonRabe (HORTGRO Executive Director),Prof Stephanie Midgley (Department ofHorticulture, Stellenbosch University),Prof Roland Schulze (Centre for WaterResource Research at the Universityof KwaZulu-Natal) and Hugh Campbell(HORTGRO Science General Manager).
http://www.greenagri.org.za/http://www.greenagri.org.za/


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As Darwin said, it is not thestrongest of species, nor themost intelligent of species,

that survives. It is the onemost adaptable to change.

Make every drop count

2016: ?

PERCENTAGEWISEthe rainsreceived since Easter 2016 have donevery little to the drought situation inthe Western Cape and to dam levelsin the province in particular. Thisis according to Andr Roux (photoright), the Western Cape Departmentof Agricultures Director: SustainableResource Management.The Clanwilliam Dam is one of thefew that saw a signicant increase of

almost 7% in its water levels within afew weeks. This is thanks to some goodrain in the Cederberg, but also the factthat the dams storage capacity is only25% of the mean annual runo. By theend of May, however, Clanwilliam Damwas still only 15.3% full.

Our soils and catchment areas aresimply too dry to allow runo, saysRoux, who highlighted that the droughtcurrently being experienced in SouthAfrica is the worst in 112 years. Weneed signicant rain spread over a longperiod to signicantly impact our watersupply situation.

He provided the gathering with aninformed perspective on the future ofirrigation in the Western Cape, and

about the water sources that will beavailable to fruit farming endeavours by2035.Making predictions about water inSouth Africa can land one in hot water,he started o on a provisory note. Hehighlighted that much depends on thepercentage of the total water supplythat is available that government willallocate to agriculture, and especially intimes of drought.

South Africa is a semi-arid countrywhere water is of critical strategic

importance. Ithas a potentiallimiting eecton all futuredevelopment ofthe country,he warned.High populationdensities andsignicantcompetition of available waterresources exaggerates this situation.

According to Roux, agriculture is at60% by far the biggest water user inthe Western Cape. Urban developmentuses another 24%. If there is watershortage, agriculture is the sectorwhere government will come lookingrst to cut back supply, he said. Hetherefore urged the audience to workbetter with the resources at hand, toreact timeously and to be innovativein their approach to water usage andmanagement.

He said that by polluting water andallowing infrastructure networksto deteriorate, humans are furtherreducing the resources available tothem and thus increase the risk ofassurance of water supply.

As Darwin said, it is not the strongestof species, nor the most intelligent ofspecies, that survives. It is the onemost adaptable to change.

Roux noted that according to the WaterAct of 1998, a certain amount of watermust always be set aside as an ecologicalreserve to ensure that environmentalprocesses are able to function well.

By 2025, all our water resources willbe fully utilised, he continued.


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Working better with water at hand

Innovation is key to mitigating the possible impacts of climate change. Roux advises theagricultural sector to:

Optimise irrigation water to mitigate the impacts of climate change against theneed to expand enterprises

You cannot manage what you do not measure. Know how much water your cropsuse to ensure high water productivity and ultimately food security.

Carry out irrigation scheduling as accurately as possible to limit water loss. Thiscould save you up to 20% in water usage.

Increase the benecial consumption of water i.e. the water used for crop transpirationand reduce the non-benecial consumption of water i.e. surface runo and deeppercolation

Understand the water/yield relationship of their crops. This will allow decit irr igation.

Consider a combination of minimum or no-tillage, retaining crop residue on the soilsurface, using mulch and crop rotation. These methods help to hold water in thesoil and reduce evaporation.

Try to produce more crop per drop.

Work carefully with the sources at hand, and do not pollute these by simply dumpingunwanted materials into rivers or streams.

Save on your electricity consumption. At least 1.35 litres of water is needed to produce 1kWh of electricity.

Keep infrastructure in good order. Leaking pipes or broken channels come at a price.

Remove alien plants in catchments and rivers, which could use up to 7% of our availablewater resources.

More than 50% of wetlands have already been destroyed due to irresponsible humanactivities. Wetlands are important to help clean water. They temporarily store water that isreleased over time into streams and rivers.

Start implementing SmartAgri, a combined eort of the Western Cape Department ofAgriculture and the Department of Environmental Aairs and Development

Planning. It aims to inform the agricultural sector about the possible impacts of climatechange and mitigating measures. Visit www.greenagri.org.za for more info.

Did you know?

On average, South Africa receives 465mm of rain per year. The annual world average is857mm.

90% of rain in the Western Cape falls in winter, when the demand is actually for only 25%.The rest falls in summer, when the demand is 75%. Therefore winter surface water runosneed to be stored in dams to ensure availability for irrigation in summer and all the more soas the impact of changing weather patterns are being felt.

Only 1% of all water on earth is available for use and need to be shared across all water usersectors i.e. agriculture, industries, domestic, electricity generation and the ecology. The restis sea water (97%) or trapped in the polar caps (2%).

The highest temperature ever recorded on earth for the

month of October a sweltering 48.3 degrees Celsius was measured in Vredendal on 27 October 2015. It caused

an estimated R10 million loss to the local wine and tablegrape industry.

The current drought situation: The state of the Western Capes dam levels

Greater Brandvlei

Theewaterskloof

Volvlei

Clanwilliam

31,5%

50,6%

42,3%

8,7%

17,9%

29,4%

21%

15,3%

30 May 2015 30 May 2016

SOURCE: Department of Water and Sanitation

This includes all water that will bestored up in the newly planned damsand transfer schemes.

Remember, no new water sources areever created, Roux cautioned. In fact,we are using the same water that was

available the time of the dinosaurs.This limited supply is recycled all thetime. He highlighted the need toimprove ecient resource managementand use to mitigate the increasingimpacts of change.
http://www.greenagri.org.za/http://www.greenagri.org.za/


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Intelligent irrigationkey

THErole of the modern irrigationsystem is much more than just givingwater to fruit trees. Implementingnew technologies to make money isa continuous eort for any innovativefruit grower and key to prot is eectivewater management.

This was the message from privateirrigation consultant, Gerhard Mostert(photo right), who urged growers toseriously consider implementing a

Centralised Low Flow Irrigation System(CLFIS).

The CLFIS gives the grower centralisedcontrol, dedicated mainlines, low owdrippers, and full automation. Ultra-lowdrip irrigation technology will not onlysave water, but it entails applying waterto soil at a rate that optimises oxygenand water levels in the root zone making it more energy ecient. Itcould revolutionise the irrigation of fruittrees, Mostert said.

The low ow dripper is the key aspectof the system and is characterised bythe emitters ability to release water ata rate of less than 1L per hour whichscales to less than 3m per hectare perhour.

Mostert says the system provideswater at the same rate that the plantis using it and brings a whole newdimension to irrigation, as the type ofsoil now becomes one less factor to beconcerned with in the growers irrigationplan. Growers who implement a CLFISwill also benet from complete irrigationexibility, according to Mostert. Growershave the option to irrigate just oneblock at a time or the whole farm.

Growers might be faced with a situationwhere they may want to irrigate 1

orchard blockthat uses 2.5m of water perhour, while atother times theremay be a needto irrigate theentire eld withsay 100 m perhour. Hence thesystem shouldbe able to handle variation of between

2.5 and 150 m of water per hour.

Mostert says this can be achieved byinstalling systems with three pumps.Despite contrary advice growers mayreceive from conventional irrigationsystem designers that using a singlepump is more ecient, he says that heonly uses a multi-pump system.

The third pump only runs 20% of thetime, the second 40% of the time,and the rst 100% of the time, saysMostert. He said the system workedwell in an operation with dry blocksand wet blocks or elds situated onslopes as opposed to being situatedalongside rivers, where dierent waterrequirements were needed after rainfall.

Another benet of the system iscomplete control of fertilisation. Mostertsaid that the industry was movingaway from the view that an irrigationsystems sole purpose was to carrywater. It makes sense - if you havethe system - to also use it to applyfertiliser. It can replace a tractor, adriver, even an entire team to applyfertiliser. Mostert said the systemintroduces the highest level of irrigationand fertiliser management and enablesimplementation by the farm managerand one other person as a pump houseattendant.

The role of the modernirrigation system is much

more than just giving water tofruit trees. - Gerhard Mostert


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He says the system gives power to oftenuseless monitoring systems throughintelligent implementation with a highlevel of control. In conclusion, growerscan expect:

Less: runo; evaporation;

leaching; labour; energy.

Improve: management; water

uptake and rainfall eciency.

Technology will never replace a farmer

TECHNOLOGYwill never replace a farmer. It is the tech-savvy farmerwho will be replacing those who still shy away from using new innovationsthat can make working in agriculture more ecient. This is according toinformation and communications technology (ICT) specialist, Martin Butler,from the Stellenbosch University Business School.

He believes that some of the most exciting applications of technologyworldwide are found within the agricultural sector. However, Butler does notsee technology as a solution per se, but rather as part of a package that alsoincludes good agricultural practices and a sound knowledge base.

Butler highlighted a major recent global study done by MIT that included

most sectors, including agriculture. It showed that companies that investsmartly in ICT generate more revenue and are more protable than others.According to Butler, it is not possible to predict what the future for mostsectors will hold:

The reality is that you will help shape the future; you willdecide what it is.

The way in which any organisation embraces technology goes hand in handwith its leadership, and the tools that are available to a particular sector.Adopters of technology are therefore classied into four groups: beginners,conservatives, fashionistas and digital masters.

PICTURE FROM LEFT:Peter Dall

(Day 2: Session 2 Chair), Martin Butler(University of Stellenbosch BusinessSchool), Prof Elias Fereres (School ofAgricultural Engineering, University ofCordoba, Spain) and Dr Walter Guerra(Laimburg Research Centre forAgriculture and Forestry).

Beginners are not interested in new technologies, while the conservatives arevery careful about investing anything if they do not rst know the possibleimpact it could have on their business. Fashionistas eagerly try out newthings, but tend to be very fragmented in the approach they follow. Digitalmasters have invested in technology, have a clear strategy for doing so andhave invested in the capabilities of deploying these.

Butler challenged the audience to not see new technologies such as dronesor tablets as mere status symbols or playthings, but to use the full potentialof these tools to the benet of the agriculture sector.

The rain in Spain stays mainly on the plain

x

WEneed new ideas to do more with less. That was the message from irrigation

specialist and agricultural engineer Prof Elias Fereres of the Department of PlantProduction at the University of Cordoba, one of the international speakers at thisyears HORTGRO Science Technical Symposium.

Fereres believes that modernisation and improvements in the ecient use ofwater have so far not really saved any water on a global scale. Water is recycledbetter within the agricultural sector, but is not yet made greater volumes availableto other water users, he said.

In his presentations, Fereres highlighted how changing irrigation methods andimproving distribution uniformity when watering crops can ensure the moreeective use of this increasingly scarce resource by the agricultural sector. Healso shared insights in how remote sensing technology with the help of drones orlow-ying aeroplanes can help farmers to irrigate smartly.


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SPANISH EXAMPLE

Fereres works for the Spanish ResearchCouncils Institute for SustainableAgriculture, and has done extensiveresearch in among others California andNorth Africa. Spain is a water scarcecountry where water volumes availableto agriculture is strictly controlled bygovernment and is often further restrictedin times of drought.

Up to 3.5 million hectares of landis currently being irrigated in thisMediterranean country. Over the past35 years its producers have changedhow they use water on farms, and

have dropped their reliance on surfaceirrigation from 90% to just below 30%.Drip irrigation is now used on 47.8% of allfarms, and sprinkler systems on another22.5% of land. With the exception ofIsrael, it has the highest percentage ofland under drip irrigation.

This shift is a reaction to increased waterscarcity and greater demand by moresectors, a realisation that farmers haveto work more wisely with the limitedresources at their disposal, and bettertechnology options. The shift has howeverseen a rise in energy costs. The trade-o is that pressurised systems and theuse of sprinklers require more energy,and therefore could cost more money,he adds. These systems are thereforenot always the best economic option,depending on the oil prices.

We have gone through an extreme

case of modernisation and investmentin Spain, Fereres told the audience.However, he acknowledges that thecountry has probably overinvested inchanging systems.

We are not really saving water, justrecycling it within agriculture.

Change ofrrigation water

proportion inhe 2030s in

relation to waterscarcity:

REDIT: CLiu J, Folberth C, YangRckstrm J, et al. (2013)

Global and Spatially Explicitsessment of Climate Change

mpacts on Crop Production andnsumptive Water Use. PLoS

NE 8(2): e57750. doi:10.1371/urnal.pone.0057750tp://www.plosone.org/arti-e/info:doi/10.1371/journal.ne.0057750

DEFICIT IRRIGATION

In times of drought it is not an option fortree crop farmers to merely reduce thearea they irrigate.

You need to use decit irrigation tomanipulate the limited supply that youhave available to obtain the best possibleresults, said Fereres.

He says the objective when makingsuch decisions in times of water scarcityshould be to enhance the productiveow of water yet minimise possible croplosses and maximize yield.

If you know the response function, youcan nd the economic optimum thatwould meet the needs of the farmer andsociety in terms of production and ofwater productivity, he said. There willof course be trade-os.

Fereres and his colleagues have donemuch research on the topic over the pastfteen years, with the aim of calculatingthe water production function of amongothers citrus, almonds, loquat and olivesand how decit irrigation can be used forthese crops.

He says that it is better to withholdwater in an orchard and to enforce waterstress at times when no fruit growth isoccurring. Then you can up the stress,he added, before noting that this can

only be done up to a point.

If you reduce irrigation during sensitiveperiods, you could knock your yield withup to 40%, he noted.

Research on citrus has shown thatespecially mandarin oranges are sensitiveto water stress, and that it could reducefruit size considerably.

REMOTE SENSING

Technology is becoming increasinglyadvanced allowing a farmer or

horticulturalist to monitor how muchwater dierent sections of an orchard isusing, and to adjust irrigation schedulingbased on these results to ensure greatereciency and eectiveness. In thisregard, aerial remote sensing techniqueswith the use of drones, small aeroplanesand satellites have made great strides inthe past few years.

For Fereres the big question still remains:how much will it cost a farmer to get suchremote sensing done regularly, and willit make sense in the long run?

He believes the use of such technologyonly starts to make economic sense if youare also able to combine it with amongothers assessments of the nutrient stateof a piece of land. It will also make moresense for larger-scale production units,rather than small farm operations.

Its always better to have more than oneapproach, he noted, before emphasizingthe importance of having a good pair ofeyes on the ground to see what is actuallyhappening in an orchard.

He believes that one years worth ofregular remote sensing data will give aproducer sucient information about thestate of aairs in a particular orchard,after which more informed decisionswithout the need for such regular

monitoring will be possible.

Precision horticulture is all aboutunderstanding in-eld variations, headded.

Local precision farming was illustrated by Dr Caren

Jarmainwho introduced space age technology FruitLook.

FruitLook is an online software programme which provides

growers with key information describing growth, water, and

nitrogen parameters visually with maps and graphs.

If you have information you can improve resource

management, you can improve production, and you can also

improve water use eciency, she said.

A FruitLook article series is currently running in the SAFJ.

Find the latest article in the June/July edition (pg 74-78).
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0Dhttp://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0Dhttp://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0Dhttp://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0Dhttp://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0Dhttp://www.plosone.org/article/info:doi/10.1371/journal.pone.0057750%0D


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Dam building 101

BYall means build a dam on your farm to make full use offast run-os during the rainy season, but do so responsibly- by the book and according to the water rights that holdfor your property.

This was the strong message from Elkerine Rossouw (photoright), water use specialist of the Breede Gouritz catchmentmanagement agency (CMA).

Rossouw conrmed that South Africa urgently needs moredams. But do your homework before you build your million rand dam, otherwiseyou may nd yourself in a position later where you do not have the correct licencingin place, she urged. Rossouw highlighted that free advice in this regard is providedby sta of CMAs across the country.

Long before you start excavation work, landowners should have conrmation ofregistration in place. You need a licence to dig a hole. You need a licence to put andstore water in that hole. You need registration proof from your water authority, orthe necessary validation and licencing from either the national Department of Waterand Sanitation (DWS) or your CMA, she noted. She warned that going through thenecessary channels could take up to 18 months. So plan ahead.

Step by step

The excavation of new dams must be done according to regulations in the NationalEnvironmental Management Act, which is implemented by the Department of EnvironmentalAairs and Development Planning (DEADP). This for instance includes an environmentalimpact assessment about the plants and animals occurring on the piece of land. Certainactions triggers listed activities. As these types of applications can become very complex innature, it is best to rst liaise with DEADP.

Dams holding more than 10 000m of water (accumulative volume per property) must beregistered at the DWS or the CMA in a particular region.

Formal authorisation and/or licencing is needed from the DWS to build dams of 50 000m(accumulative volume per property)

Note that accumulative volume per property refers to the combined total volume of waterstored on a property, and not just in one particular dam.

For free advice on the processes that need to be

followed and be put in place, contact representativesof your local catchment management area:

Darril Daniel/Asla Pieter Berg-Olifant CMA:023 346 8000 or [email protected]

Elkerine Rossouw - Breede Gouritz CMA: 023 346 8000 [email protected]

WHY CMAS

Catchment Management Agencies were set up according to Chapter 7 of theNational Water Act, 1998 (act 36 of 1998) to bring the control, management andthe responsibility of looking after this scarce resource to local water user level.

The National Water Act required South African water users to register their water use.The information was captured on the Water Authorisation Registration ManagementSystem.

The process of validation and verication has started in some areas within theBreede-Gouritz CMA (and possibly others). This is done to verify that the wateruses registered were done correctly. To be able to make informed decisions abouthow much water is available to allocate in future for environmental and water userneeds, we must know how much water is available in a catchment area and howmuch is actually being used, Rossouw explained at the HORTGRO Science Technicalsymposium.

CMAs are also responsible to:

Investigate and adviseon the protection, use, development, conservation, managementand control of water resources in a particular water management area (WMA)

Develop a Catchment Management Strategy(CMS)

Coordinaterelated activitiesof water users and water management institutions within aWMA

Coordinate plans about integrated development, water services development and otheractivities performed by local governments such as municipalities

Promote community participationin Integrated Water Resource Management

In search of the apple

NOTall apples are created equal and it is only throughrigorous testing that the best adapted and potentiallymost protable ones can be identied. This was one of thekey messages of Dr Walter Guerra, head of the PomologyDepartment at Laimburg Research Centre in South-Tyrolat the 2016 HORTGRO Science Technical Symposium.

Up to 200 new selections and cultivars are screened andtested at Laimburg every year, mainly to see how wellthey will potentially perform in South Tyrol's dierentproduction regions. This includes over 30 Gala mutations,which are screened for genetic stability, percentage redcolour, ripening etc.
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For the market, it is the redder the betterinsofar as Gala mutants are concerned.Old fashioned clones like Royal Galaand Mondail Gala are just not producingenough colour, Guerra indicated. Newer,redder clones are therefore favoured.

No signicant dierences betweenGala clones have been observed interms of harvest maturity, inner qualityor storability, if harvested at thecorrect harvest maturity, he indicated.However, the newest generation of Galamutants starts to colour much earlier,which can make it tricky to assess thematurity of individual fruit on the tree,he cautioned.

When it comes to genetic stability, notall the clones in the Gala family areequal, he said. Systematic evaluationssince 2014 on more than 2000 Galaorchards in South Tyrol have indicatedconsiderable dierences in stability.Some clones such as SimmonsBuckeye, Gala Decarli, Fendeca andGalava are considered 95% stable andcan be recommended for planting whilesome others are more unstable.

Walter and his team dont only evaluatecultivars and selections but they arealso actively involved in apple breeding.

NICHE MARKETS

Apart from breeding for the mainstream

market, they are also interested insome niche markets, such as thosefor hypoallergenic apples (2% of thepopulation is allergic to apples), sweetbut low sugar apples that could be moresuitable for diabetics or people whoare fructose-intolerant, and geneticallysmall (50mm) mini-snack apples thatare ideal for packing in childrens lunchboxes. Yellow alternatives to GoldenDelicious, supersweet and seedlessvarieties, as well as scab resistantapples, are also in the future.

Walter sees a gap for red-eshed apples up to 80% consumers indicated awillingness to try such apples.

APPLE PRODUCTION IN

SOUTH TYROL

South Tyrol lies in the Alps in northernItaly and boarders on Austria andSwitzerland think Heidi ...

One in every 10 apples produced in theEU and 30% of all organically producedapples in the EU come from here.

The main cultivar is Golden Deliciousat 42% of production followed by Galaat 16%.

The 18,400 ha consists of about 8,000family-run farms with an average farmsize of about 2.8 ha.

Production areas lie from 200m abovesea level to 1200m, with very coldwinters and hot summers of above40C in the low valley.

Because of this variation, there is aneed to test the performance of newcultivars/mutants on dierent sites,and to nd out which ones will be themost suited.

CURRENTLYonly 30% of ourapple orchards

are adequately chilled, said Dr NigelCook (photo above), horticulturist fromProphyta. This has a signicant eect onbud burst and tree growth in the warmerapple producing regions. Many of SouthAfricas apple trees already suer fromchronic sleep disorders given our mild

winter conditions, he says. Given theabsence of enough chill accumulation,more than two thirds (70%) of our appletrees need to be chemically manipulatedout of dormancy.

Cook spoke about the hidden costs forlocal apple growers associated withthe lack of winter chill. Local growersproduce apples closer to the equator inareas with much milder winter conditionscompared to nearly all other productionareas in the world. Apple productionat our latitude is only possible becausewe can plant apple orchards at higheraltitudes.

He highlighted the results of a ve yearlong dormancy progression study ofGranny Smith and Royal Gala trees

in all our dierent production regions.The low chilling conditions are having asignicant eect on the progressionof bud dormancy. This is becausesucient winter chilling is needed forplant growth and to ensure synchronisedbud break in spring.

It is believed that cold autumn andwinter temperatures enhance both whenthe plant enters and exits this deeprest period. If the chill requirementsof the trees are not met during winter,this has all sorts of knock-on eects.The bud burst percentage is low, the

trees are owering unevenly and thiscauses uneven fruit set as well as mixedmaturity of fruit on the tree later on,he explained. It also causes the startof a basal dominant apple tree becauseit aects which spurs and shoots aredominant.

If left untreated in spring, we would haveapples developing while some owers

only bloomed last week and some budsare still waking up and all of this inthe same tree. This is not ideal.

Currently producers use oil and Dormex(cyanimide) as rest breaking agents totry and synchronise trees in and outof winter. Dormex, can be hazardousand toxic to both man and plant if notapplied correctly, and may in future notbe available for use. Many producerschanged the way they train the treesas an adaptation to the lack of chillingconditions. Solaxe-training enhancesthe reproductive eciency of the treein warmer areas.

It is all about creating dominantterminal buds on the branches, alsoknown as spur autonomy. By bending

the branches we are developing more,stronger spurs.Given that Dormex may not be onthe market forever, a breakthrough isneeded in rest breaking technologies,Cook said. We urgently need cultivarssuited for low chill conditions that willgrow normally, have proper colour andbe sunburn-resistant.

Also see Dr Esm Louws article ondormancy in the June/July edition ofthe SAFJ (pg 82-87).

Photo right: Dr WalterGuerra (LaimburgResearch Centre forAgriculture and Forestry)

Not chilled enough


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NOT CHILLED ENOUGH

Right: Delayed foliage dueto inadequate winter chill.

:

GROWING deciduous fruit trees inpots holds great potential to develophealthy nursery material and build theresilience of local fruit orchards.

This was the message from ProfKaren Theron of the Department ofHorticultural Science at StellenboschUniversity, highlighting issues aroundnursery tree health and quality at the

symposium. As indicated by researchdone by Dr Lizel Mostert, we do haveproblems in terms of health issues innurseries in our industry.

In addition, one of the biggest problemsrevolves around the transplant shockbare-rooted nursery trees experiencewhen transplanted into the orchard. Ibelieve that growing trees in containersmight oer viable alternatives in thisregard, Theron said.

She also discussed using tissue culturetechniques as alternatives to produce

clean nursery rootstock material. Somechallenges remain, for instance inpropagation, as well as cost implicationsof trying out alternative ways to producehealthy trees for local fruit orchards.

Tissue culture propagation is alreadyviable on a large scale, she said. Thishas been proven in many other partsof the world, including in Spain. Some

local producers and laboratories arestarting to experiment with this as well.Theron said it is entirely possible toproduce healthy young trees suited forplanting within a year with tissue culturetechniques. We can grow healthy,disease-free trees from start to nishusing sterile medium and it can be readyfor transplanting in spring or autumn.

Theron believed transplant shock couldbe minimised signicantly by growingnursery trees in pots or bags. We knowthat damage to the root system is oneof the greatest risks during the handling

Utopian options for nurseries

and transplantation of nursery trees.Growing them in bags or pots could helpto reduce root loss. We need to keepthe root system intact during planting.We should always be looking at waysto guarantee better quality plantingmaterial. In my view our nurserystandards needs to be re-evaluated andsome alternatives explored in order tooer improved services. Tissue culturetechniques might oer one such analternative.

Theron compared the very complicatedprocess of making a clonal avocadotree for approximately R85 per tree tothe less complex process that would be

needed to make a clonal deciduous fruittree. She says this should cost aroundR50 to R60 per tree. Clearly we havesome issues to work out, includingaround costs. According to Theron the

hidden cost of trees not performing in theorchard should also be factored in whendecisions are made about implementingnew and or conventional methods.

I believe growing trees in containersoers food for thought for everyoneinvolved in the nursery industry, sheconcluded.

Tissue culture takes root

TISSUE culture potentially oersmany advantages to fruit producers, this is the opinion of Hannes Laubscher,Director: Technical Services at DutoitAgri.

Laubscher discussed using tissueculture in the local fruit industry duringhis presentation at HORTGRO Sciencesrecent Technical Symposium. Tissueculture can potentially help to improvethe quality of the available rootstocksfor local producers, he believes.

Laubscher considers the rst attemptsof using tissue culture locally aspromising. He referred to good resultsDutoit Agri has had with a tissue culturecherry orchard established in 2012near Worcester. Only one of the treesin this orchard has died compared tomany others in another nearby orchardestablished in the same year but on

conventional rootstocks. Dutoit Agriis also now exploring tissue cultureto establish new stone fruit and appleorchards, he says.

Tissue culture is widely used to produceclones of plants in a method known asmicro propagation and may oer certainadvantages over traditional methods ofpropagation, he explained.

The advantages of tissue culturetrees are many, he says. With micropropagation stock plant material canbe rapidly multiplied to produce largenumber of progeny plants, he says.This is the main advantage of micropropagation. Micro propagation canalso be used to produce disease-free and more robust plants. A greatnumber of plants can also be producedper square meter and the young plantscan be stored in a smaller area (in a


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laboratory or nursery). Micro graftingis currently not big in South Africa,yet it is something that we can easilydo. In Spain this technique is alreadyemployed to produce the majority ofstone fruit.

Some challenges will however need to beaddressed in order for trees propagatedwith tissue culture to be used more widelyin South Africa, he says. Currently thecost factor is the most important barrier.These tissue culture trees are currentlyquite expensive. Regarding the importof tissue culture plants, there are alsosome issues around import regulationsand quarantine of plant materials,

as well as around timing of delivery,uniformity and quality. Laboratorieswill also have to produce large volumesto make it nancially viable for them to

invest in capacity and research. Usingtrees generated through these newpropagation techniques will also requirea mind shift for growers.

According to Laubscher another bigchallenge locally will be to producethe necessary volumes. He reckonsthe industry needs to give guidanceregarding to the choice of rootstock tosimplify the process. Local laboratoriesare not 100% on par yet, but willquickly need to catch-up. We need tostart the process and propagate theidea in South Africa to bring down costsand make it a viable option.One way of doing this is to focus eorts

on only a couple of rootstocks. It willmake it easier for nurseries to achievesuccess he said.

Arecent study looking at young appletrees in local nurseries has providednew insights into the occurrence ofstem canker and wood rot pathogens inapple nursery trees.

Almost two thirds (61%) of nursery treesstudied (295 out of 480 trees) harbouredcanker or wood rot pathogens, saidDr Lizel Mostert, senior lecturer fromthe Department of Plant Pathology atStellenbosch University.

Mostert, who has been researchingthe status of stem cankers in localnurseries since 2015, says it remainsa cause for concern for the industry.Ideally we would want to plantentirely healthy trees, she said. Thisis because the phytosanitary qualityof nursery trees plays a large role inhow successfully young apple trees canestablish themselves and growers can illaord trees to die-back after planting,considering the cost of planting a neworchard.

Cantankerous Nursery Trees

Mostert presented her ndings atHORTGRO Sciences annual TechnicalSymposium last week. She collaboratedwith researchers from ARC Infruitec-Nietvoorbij and ProCrop Trust on thisproject. The researchers looked atstem canker and wood rot pathogensin mother blocks, nursery trees andyoung orchards. They used GoldenDelicious trees from four dierent localnurseries. In all of the nurseries therewere similar levels of trees with stemcanker pathogens. On the outside thenursery trees did not look infected atall, but if you cut through plant materialthe typical discolouration causedby infections and stem cankers was

observed, says Mostert.

It appears that 56% of the mother blocksinvestigated (140 out of 250 trees) wereinfected with pathogens. Pathogenswere also isolated on the young treesthat correspond with those that causestem cankers in adult apple trees, shesays. In a third of the 1-year-old treesstudied, the percentage of the infectedplant parts was highest for graft unions,followed by 22% for pruning wounds,17% for scions and 11% for rootstock.Wood rot fungi associated with mucholder trees were also observed in

nursery and young trees, she indicated.This is very disconcerting as the kindof symptoms we observed are normallyassociated with much older trees. Yetwe see nursery trees being infectedand white rot developing from pruningwounds.

But not all infections on nursery trees ledto stem cankers. Stress seems to playa big role whether or not it develops,Mostert said. We also need to lookcloser at the role of areal inoculation andat the pathogen status of some of thefungi we observed on the young trees.

She alluded to the fact that they

observed stem cankers on 1-year-oldtrees growing in a soil with a pH of 4.8 orlower. It is possible that this can lead totoxicity and that planting on certain soilswould put stress on the young trees thatcould trigger these stem cankers. Weneed to understand these issues betterto help nurseries ensure that woundsmade in the nursery are well sealed anddo not become infected, she says.

Mostert pointed out that there was ageneral perception that stressed treeswere more susceptible to stem cankerthan healthy trees.

The bottom line is that healthy trees

are more resistant to disease, thanstressed trees. Trees with latent stemcanker might perform optimally for

years, if the trees are not subjected tostress.


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Biological control: Monitoring mites into

oblivion

INthe battle against mite infestations,veteran entomologist Dr Ken Pringletold fruit growers that he was not goingto mention chemical control because itwas considered unsustainable.

Mites have developed resistance to ahuge number of chemicals and eachtime an insect develops resistance to achemical, it enhances their detoxicationsystem and the life span of a miticidenowadays is not more than two years,said Pringle, who carries out research

at Ste llenbosch University.

Pringle proposed biological controlusing natural predators of mitestogether with a monitoring system. Thepredatory mites in the growers arsenalinclude the multi-chemical resistantcalifornicus (Neosiulus californicus)and the indigenous rubicolus (Euseiusrubicolus).

The monitoring system was basedon dividing orchards into blocks ofapproximately 2 Ha where 25 evenlyspaced trees are marked as monitoring

trees in the blocks. One leaf is takenfrom the inside and one from the outsideof each tree. In the case of apples eachleaf is classied as infested or un-infested. In the case of pears the adultmites are counted on each leaf, Pringleexplained. Monitoring is based only onpest mites as the predators are dicultto see. However, if seen, their presenceshould be noted.

Referring to thresholds in apples Pringlesaid the chances for biological control

increases with higher levels of miteinfestation. There are very few cases ofsuccessful biological control when 40%or less leaves are infested, while thereis successful biological control in about50% of the cases when 40-80% of theleaves are infested, and when 80% ormore leaves are infested there is a goodchance of biological control, he said.

Pringle advised growers not to spraybefore 40% leaf infestation and if theywere serious about biological controlthey should wait until at least 80% ofthe leaves were infested.

Optimising spray efciency

HOWEVER, should growers have a need to spray, the eciency of theirspraying systems was an important factor to consider according to GroupMarketing Director at Rovic Leers Marius Ras.

Ras said the migration to trellised spindle type orchard systems had takenthe tree structure to a stage where the depth of the tree has decreased to aslittle as 0.5-1m.

Spraying through the target is now the biggest contributor to bad recoveryand drift, according to Ras.

The single biggest contributor to the problem was the mismatch of the airmomentum and air velocity prole supplied by the spray apparatus with thetree structure.

Despite the absence of nal statistical deductions, rst trial results

have shown that a sprayer with a turret that can deliver a (proven)linear horizontal air velocity prole seemed to outperform all othermachine geometries, and could have the ability to be used at higherground speeds in spindle tree structures with positive results.

Read Rass full article on the Need for Speed here: http://bit.ly/1rt8WzY

Carbon dioxide (CO2) and the story of an apple

producers worst nightmare

IN2015, Ceres Fruit Growers Bibbie Potgieter had an apple producers worstnightmare play itself out in waking day

Potgieters voice became slow and measured as she recounted her experienceto delegates at the HORTGRO Science Technical Symposium 2016.
http://bit.ly/1rt8WzY%0Dhttp://bit.ly/1rt8WzY%0D


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Our Fuji [apples] were packed and shippedon the 2nd of April 2015 and arrived inthe Far East on the 25th of April 2015. Onarrival the fruit was in very good conditioninternally and externally, our presentationin the carton was very good, and we evenreceived complementary mails to say thatthis was fabulous fruit. However, withinthree days after the fruit was sold wereceived absolute horric photographs,Potgieter said, and proceeded to showstunned delegates cartons of what lookedmore like raw 2-dimensional kidneys in abutchery than half cut Fuji apples.

This event set her o on an arduousjourney to determine the possible causesfor her ruined consignment.

Her action plan included a series ofimmediate actions, a research and

technical team of no less than 8 people,an evaluation of internal browning types,orchard/fruit variance assessment, anassessment of cooling protocols, internalfruit CO, and a series of trials.

Despite all her eorts Potgieter was unableto replicate the extent of internal browningfound in that April 2015 consignment, buthad a strong hunch that CO was to blame.

According to Prof Michael Reid from theUniversity of California Davis, who deliveredthe postharvest keynote address, theproblems inside apples could have been

solved long ago in the 1800s.

If Sir Isaac Newton, instead of worryingabout the force of gravity when the applefell on the ground, had worried why theapple went brown in the bruised area,Reid quipped in his talk on the causes ofinternal browning.

However, a lot more than Newtons physicsis needed to pin down the cause of thepost-harvest end.

Biochemistry, Molecular Biology,Biotechnology, Cell Biology, and Calculus areall needed to describe a process which tendsto be more complex than simple.

In accordance with Potgieters gut feeling,previous studies in the US also suggest thatCO was to blame for internal browning inFuji apples.

According to Reid C0 was toxic for a rangeof reasons including its ability to alter pH,aect enzyme function, inhibit aerobicrespiration, and an ability to stimulateproduction of alcohol and acetaldehyde.

To make matters worse Fuji appears to bevery sensitive to as little as 0.4% externalC0, this is in contrast to other appleswhich are often stored at between 0.5-1.5% C0.

Reid turned to the mathematical conceptof calculus to explain how C0 causes

mayhem in the inside of an apple.

He likened the apple to a bathtub with wateras C0, entering at a faucet and leavingat the drain. The main question then is:what would increase water levels?

In Reids apple-bathtub analogy waterlevels will increase through increased owinto the tub (increased C0 productionthrough temperature and ripening),impeded ow from the drain (the peel is amajor barrier to gas), and a ooded oor(high external C0 through controlledatmospheres and sealed containers or

bags).

So, it is likely that C0 levels were toblame for Potgieters Fuji consignmentmisfortune but Reid suggested that eshbrowning may also result from dierentstressors, particularly between orchardsand seasons.

STRATEGIES TO MINIMISE RISKOF INTERNAL BROWNING

Identify high risk areas and seasons monitor risk!

Good crop load management optimalfruit

Correct CA management

Ensure good air circulation in storagerooms

Postharvest treatments and packaging

Test new storage regimes and procedures Conditioning of fruit

Use of SmartFresh (1-MCP)

PICTURE ABOVE:Richard Hurndall(HORTGRO Science Research and TechnicalManager) and Prof Michael Reid (PlantSciences Department, UC Davis, USA)

Playing it safe with DPA

THESouth Africanfruit industry can

be ready, shouldthe maximum levelof residue (MRL)of the chemicalDiphenylamine(DPA) allowedon apples andpears exported to

Europe drop even further in 2017. Thisis according to researcher Danil Viljoen(photo) of ExperiCo (Agri ResearchSolutions), who has conducted relevanttests since 2013 to gauge the lengths towhich producers and pack houses should

go to prevent DPA cross-contaminationof fruit destined for lucrative European

Union (EU) markets.

According to Viljoen, the local industryisnt yet DPA-free, but levels havedenitely dropped since strict regulationsregarding its use were put in place bythe European Commission.

DPA was initially developed to keeprubber stable, but has been used sincethe 1960s also in South Africa to controlunsightly supercial scald on Packhamspears and apples such as Granny Smith,Red Delicious, Cripps Pink, Cripps Red


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and Goldens during storage.

Because of a possible adverse eect onhealth, the EU banned the use of DPAin its 28 EU member states in 2012.Since 2014, fruit containing residueof more than 0.1 ppm of DPA are alsosummarily rejected when imported tothe EU which could be a costly exerciseworth millions of Rands to South Africanexporters found wanting.

CUTTING DOWN ON CROSS-CONTAMINATION

The worry still remains that fruit destinedfor Europe could in some way become

contaminated with impermissible levelsof DPA, even though these were nottreated with the chemical as such.At the HORTGRO Science TechnicalSymposium, Viljoen gave exporterspeace of mind, by highlighting denitiveways by which they can ensure thattheir shipments always stay within theDPA limits.

After having been used for decades, DPAresidues, accumulated on the exposedsurfaces in cold stores, on bins, umesand pack lines could contaminateuntreated fruit even with no DPA onsite. In reaction to the EU ban, mostpack houses have in the past few yearstherefore already gone to great lengthsto clean contaminated surfaces with,for instance, oxidizing agents such as

chlorine, ultra-violet light, peroxides,heat and steam.

Many packhouses have also stoppedusing DPA and have installed DynamicControlled Atmosphere (DCA) coldrooms as a chemical-free way to curbthe development of scald. Otherstechniques include initial low oxygenstress (ILOS) methods, or the post-harvest application of 1-MCP.

Some still however use DPA to treatfruit destined for non-EU countries. Indoing so, they do run the risk of cross-

contaminating apples and pears set forEU countries that are kept in the samefacility, warned Viljoen.

He also warned that this could happenwhen the same scrubber is used for fruitkept in DPA treated as well as untreatedcold stores. Flume water used on thepack line was thought to be possiblesource of contamination, but researchshowed that risk of contamination wasvery low.

In another study conducted by Experico,traces of DPA were found on fruit 14weeks after being stored in old woodenbins. However, residue levels were still

well below the MRL of 0.1 ppm. Noresidue was detected on fruit stored innew plastic bins, old plastic bins or newwooden bins.

Residues above the MRL of 0.1 ppmwere also found within four weeks onuntreated fruit kept alongside DPAtreated fruit in one cold store.

HOW TO PREVENT CROSS-CONTAMINATION

With the following recommendationsin place, it is unlikely that a furtherreduced MRL will signicantly aectfruit exports to the EU, says Viljoen,who is continuing his monitoring workon DPA in the local industry.

If at all possible, do not use DPA at asite.

Do not store DPA treated and untreatedfruit in the same cold store.

Do not share a scrubber between DPAtreated and untreated cold stores.

Ensure that sampling for DPA levels isdone correctly.

Keep DPA treated fruit samplesseparate from others, to prevent therisk of unwanted contamination.

There is life after DPA for Packhams Triumph

pear exporters

THEREis life after Diphenylamine (DPA),and theres ample research to prove it.This is according to consultant Kobusvan der Merwe (photo), formerly fromthe Agricultural Research Council (ARC)and Anl Botes, who is now furtheringhis research on Packhams Triumphpears at Infruitec-Nietvoorbij.

Van der Merwe said that the industryworldwide has responded admirablyafter the announcement by the European

Union that fruit exported to its memberstates should be practically DPA-free.

We have lost DPA but we are comingup with solutions, he said.

At the HORTGRO Science TechnicalSymposium, Van der Merwe presentedndings of research conducted by theARC and postgraduate students atStellenbosch University. They applieddierent Controlled Atmosphere (CA)technologies by which to inhibit thedevelopment of supercial scald instored pears. These include ControlledAtmosphere Storage (CA), Initial LowOxygen Stress (ILOS), and DynamicControlled Atmosphere Storage-Chlorophyll Fluorescence (DCA-CF)techniques.

With CA, fruit is stored in a gas-tightroom while the concentration of oxygen(O2), carbon dioxide (CO2) and thetemperature in the facility is controlled.The technique reduces the rate ofrespiration, as well as retaining rmnessand colour.

Dynamic controlled atmosphere storage(DCA-CF) techniques are similar to CA,but fruit is kept at oxygen levels justabove its anaerobic fermentation pointor the so-called low oxygen limit (LOL).Fruit is therefore stored at the lowest

p o s s i b l eo x y g e nlevel beforefermentationsets in.This level isdetermined bythe physiologyof the fruit.To ensure that it is done correctly, thestress point of the fruit being storedis continuously monitored using the

chlorophyll uorescence technology.

With the Initial Low Oxygen Stress (ILOS)method, fruit is stored at 0.5% O and1% CO for 10 to 14 days. Thereafter thefruit is stored further according to therecommended controlled atmospherestorage (CA) regime for pears.

Research conducted by Tlou MelroseRamokonyane at Stellenbosch Universityshowed that DCA-CF is the mostsuccessful option for the long-termstorage of Packhams Triumph pears.It inhibits the development of scald upto seven months while in cold storage.In turn, the use of ILOS along with CA ismore suitable for the short-term storageof these pears for up to ve months.

Tests conducted at the ARC showed thatpears stored for up to 8 months underDCA and then treated with the ethyleneinhibitor 1-MCP (known as SmartFresh)before being shipped were more rmand had a better colour than untreatedfruit.

Smartfresh inhibits respiration and theripening of fruit by blocking ethylenereceptors, thus extending storage lifeand ensuring that fruit quality is retainedbetter during the storage period,explained van der Merwe.


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Thanks to a Postharvest InnovationFund grant, Botes is now testing theeectiveness of the Repeated Initial LowOxygen Stress (RILOS) technique on CAstored fruit. RILOS amounts to stressperiods every 15 to 25 days during whichthe ILOS technique is administered.This raises the ethanol level in the fruitto a set threshold. This process needsto be carefully monitored.

Research has been conducted overseason the Automatic Control of Respiration(ACR) technique, by which the respirationquotient (the ratio between CO2/O2)is determined in an entire room full offruit at once. ACR allows for the storage

of fruit above the fermentation point.

WHATS THE FUSS ABOUTSCALD?

It is a physiological condition whichdevelops when some susceptible appleand pear cultivars are kept in coldstorage for long periods of time.

Unsightly brown discolouration appearsbecause of the breakdown of naturalanti-oxidants in the skin of the fruit.

Although not at all harmful, it inuenceshow fruit looks to consumers.

Symptoms normally appear when fruithave been stored for at least 8 weeks.

Symptoms are initiated in coldstorage and usually develop within 3to 7 days after the fruit is transferredto ambient temperature conditions.

To cool or not to cool?

QUALITYfruit is what consumers want. Therefore how

fruit is handled after picking is an important step in thehandling protocols of stone fruit. But what to do, whenyou are sitting on Gamoep se vlakteand cooling facilitiesare not readily available?

To answer this question Experico researcher, Arrie de Kock(photo left), did some trials and investigated the optimalhandling protocols for apricots and plums transported from

distant production areas that were far from cooling and loading facilities.

According to De Kock they wanted to determine the eect that dierenttemperatures had on fruit quality from packing to cooling. We simulateddierent handling scenarios and obtained dierent temperature proles, deKock said. The three scenarios were: fruit loaded warm, fruit cooled on sitebefore transport and eld heat removal (FHR)on site before transport at 2.0C.

The results for the simulated cold storage of apricots:

There were no signicant dierences between fruit loaded cold or warm However, cold fruit was rmer after cold storage and had less internal disorders Where eld heat was removed prior to loading the fruit, the fruit was softer and

developed more internal disorders compared to apricots that were loaded cold orwarm.

Recommendations for apricots:

- Option 1: Pick, pack and FAC cool within 6 hours of harvest- Option 2: Pick, pack and transport to cooling facility within 12 hours after harvest Please note that partial cooling or FHR to 10C had a negative eect on quality andis thus not recommended, De Kock warned.

Results for plums:

Fruit loaded warm were signicantly softer and tended to have more mass lossand shrivel than fruit loaded cold or where eld heat was removed prior to roadtransport.

Preliminary recommendations:

- Pick, pack and FAC cool within 6 hours of packing; or

- Field heat can be removed prior to or after packing by placing bins or pallets in acold room at 10C to 12C prior to transport in a refrigerated truck.

- A time delay of 12 hours or more between harvest and FAC may lead to softerfruit and more moisture loss and shrivel.

De Kock said that stone fruit growers should take note that if there is a time delayof 12 hours or more between harvest and FAC - apricots and plums do not reactthe same to FHR.

In the case of apricots FHR prior to the transport of fruit from areas 6 hoursor more from cooling facilities had a detrimental eect on fruit quality, thereforeapricots should be cooled to -0.5C or should not be cooled at all before transport

in a refrigerated truck. In the case of the latter cooling should commence as soonas the fruit arrives at the cooling facility.In the case of plums FHR had a positive eect on esh rmness and there was areduction in shrivel. If it is not possible to use FAC immediately after packing, it isrecommended that growers FHR before plums are transported.


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The good, the bad and how to save us from the

ugly

DECAYEDfruit is of no use to retailersor consumers and results in hugeeconomic losses to the fruit industry.Therefore, scientists are continuouslysearching for the best possibletechniques to protect fruit againstdecay.

Dr Ida Wilson, specialist in cropprotection at Experico Agri ResearchSolutions, evaluated fungicide ecacy

for decay control using dierent sprayvolumes, product concentrationsand methods of application. Thisinvestigation was done on plums,nectarines and peaches.

According to Wilson, industry arebattling with decay control, since thechoice of registered fungicide productsare limited, fungi have becomeresistant to some fungicides andconsumers and regulatory bodies areputting pressure on the fruit industryto use less agrochemical inputs, froman human and environmental healthperspective.

The aim of the study was to investigateif there are variables, within theapplication methodology of fungicides

that could potentially contribute togreater fungicide ecacy in the controlof brown rot and grey mould of plums,peaches and nectarines.

Wilson induced grey mould decay(Botrytis cinerea) or brown rotdecay (Monilinia laxa) in the stonefruit, respectively, and subsequentlyevaluated fungicide ecacy for decaycontrol. Evaluations were done fortwo active ingredients, Fludioxonil and

Iprodione, with a dip vs an atomiserapplication (only for plums), or at twovolumes of application. In the interestof testing fungicide residues on fruit,three dierent product dosages werealso tested.

CONCLUSIONS

The conclusions of this study, overboth brown rot and grey mould, are

summarised in Table 1. For Iprodione astandard volume application was moreoften more ecient in decay control(1.2L water/ton fruit), whilst forFludioxonil a high volume applicationwas more often ecient in decaycontrol (3L water/ton fruit). The dosageof application made little dierence togeneral product performance, althoughthe residues responded to dierentdosages of application. Registereddosages should always be applied asindicated on the product label.

Table: A summary of results over the twodecay types, for two methods, two volumes

and three dosages of application

IN SUMMARY:

- Method, volume and dosage of product application may inuence fungicideecacy on stone fruit

- Notably, in some instances poor decay control was correlated with high presenceof fungicide residue

- In contrast, excellent decay control was also observed in fruit with littlefungicide residue

- Dosage had very little impact on general decay control by products, butinuenced compliance to MRLs

Wilson said that although the impact of fungicide application methodology wasevident, further investigation of these parameters in a commercial environmentwill be needed to make industry relevant recommendations.

Take-home message

Fungicide ecacy can be enhanced by the right choice of active ingredient,method of application and volume of application.

CATTS, Vapormate show promise in

postharvest pest control

POSTHARVEST industry players havebeen introduced to two new postharvestmitigation treatments for phytosanitaryinsect pest control.

HORTGRO Science researcher Dr ShelleyJohnson introduced the ControlledAtmosphere Temperature TreatmentSystem (CATTS) and Vapormate, anon-residual fumigant.

CATTS uses a synergy of atmosphericand heat stress to eliminate its insectpest target.

In terms of atmospheric stress Johnsonexplained that the low O/High COatmosphere inhibits normal internalfunctioning of the pest.

Reduced oxygen levels do not supportactive metabolism, high carbon dioxidelevel prevents spiracles from closing andCA (Controlled Atmosphere) conditionsinhibit upregulation of heat shock

proteins, said Johnson and added thatheat stress acts to dehydrate and breakdown the pests metabolic systems on alarge scale.

Johnsons current research project atStellenbosch University which looksat CATTS and chill-sensitive plumscultivars showed that the banded fruitweevil was least tolerant, false codlingmoth had intermediate tolerance, andgrain chinch bug was most tolerant toCATTS.


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The second weapon againstphytosanitary pests, ethyl formate (EF),Johnson described as a colourless liquidwhich was ammable.

EF deprives the pests body of oxygenthrough chemical asphyxiation byinhibiting the functions of a key enzymeit needs for normal functioning.

Johnson said the insecticide was ahistorical fumigant for dried fruit pestsand has been used since the 1920s.

EF can be applied to produce in liquidform at smaller scales but could be arisk in large-scale applications due to

ammability.

Research was done to look at whatgases it could be mixed with to reduceammability and this is how Vapormatecame into being, Johnson said.

Vapormate is a mix of EF combinedwith CO2, which reduces ammabilityand also has a synergistic eect of theinsecticidal properties of ethyl formate.

There is also the benet of using lessEF when applying it as Vapormate,according to Johnson.

The fumigant was fast-acting and gotto work between 1-6 hours on freshcommodities and up to 24 hours on

stored products.

Johnson said Vapormate was aregistered postharvest treatment forphytosanitary pests in Australia, NewZealand, South East Asia, Israel, andthe USA.

In the latter countries it was used tocontrol hitchhikers like spiders and antsand pests including mites, mealybugs,apple moth, rose weevil, and scaleinsects. It was applied using containeror tent fumigation techniques.

Johnson is currently carrying out a studywhich investigates the eectiveness of EF

fumigation on pear and plum cultivars,with a focus on grain chinch bug.

Preliminary results show 100% mortalityof grain chinch bug with no phytotoxicity.

Despite the potential of the twopest mitigation measures; Johnsonhighlighted challenges to widespreadapplication which for CATTS includedheat damage and the need for CAchambers that could be heatedeectively and suciently.

The major challenges for Vapormatefumigation included obstacles in theregistration of the product, labourintensive application process, andavailability.

PICTURE LEFT:Dr Ida Wilson (ExperiCo)and Dr Shelley Johnson (StellenboschUniversity and HORTGRO Science )

FCM: Full frontal attack needed

IN the war against the False CodlingMoth (FCM), an attack on all fronts isneeded, according to Chempacs TomLabuschagne.

Labuschagne was speaking to delegatesat the HORTGRO Science technicalsymposium 2016 eld day for stone fruit.

You cannot just [attack] one front andthink you will win, he warned.

Labuschagne said all the various lifestages of the FCM need to be targeted for

eective pest control.

FCM is an indigenous phytosanitary pestwhich is a major problem for fruit growersand has an extremely wide host range. Thisoften results in crop hopping followedby population increases.Labuschagne said a mind shift in thebattle against FCM was needed.

The control of FCM populations isonly possible if grandmothers andgrandfathers are targeted. Pest controlactivities need to be carried out early inthe season when the population is at itslowest.

However, before an assault on FCM canbe carried out physical monitoring isnecessary. Labuschagne recommended

physical pre-harvest fruit assessmentscombined with pheromone baited traps.

The rst line of attack is on the adult stageusing mating disruption (MD) or sterileinsect technique (SIT). Labuschagnesays MD, which uses sex pheromones toprevent males from nding and matingwith females, is available but has notyet been registered for stone fruit. Hesays that the key to success in the useof SIT is the ratio of wild to sterile malesand can only be achieved by combiningdierent control methods (Integrated

Pest Management).The second line of attack is on FCM eggs,says Labuschagne:

There is very little you cando to the egg because thereis nothing registered, weare stuck with what naturegave us parasitoids andpredators.

The rst instar larvae are the mostsusceptible stage in the FCM life cycleand should be the growers third line ofattack. This stage can be attacked withseveral methods including registeredtraditional pesticides, granulovirus, andnatural enemies. Labuschagne says thewindow period is crucial and that thechosen measure should be synchronisedwith hatching of the eggs.


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Charl Stander (Franschhoek Marketing-tegniese adviseur), het die volgende

nuwe aanplantingsriglyne vir jong bome gegee:

Berei grond betyds voor en maak chemiese regstellings

Besproeiing in plek voor plant

Opleistelsel in plek voor plant

Maak seker dat wortels van jong boompies nie uitdroog nie

Behandel wortels met Agrobaterium Ras 84 voor plant

Maak seker dat geen lug in grond is direk na plant nie gee water

Behandeling teen aalwurms indien nodig 4-6 weke na plant grond temperatuur belangrik

Hou leier(s) dominant

Maak seker 3:1 beginsel word gehandhaaf

Maak bome vas indien in winderige area

Moet nie sytakke by sekere kultivars te gou plant buig nie

Bestuur regop groei (rugryers)

Begin met jong boom bemestingsprogram rondom September en hou vol tot Maart Ondersteun boom gedurende eerste paar maande met blaarvoeding

Ken jou kultivar

Grondtipe

Sout gronde

Besproeiing skedulering

Besproeiing tipe: drip- en mikro-stelsel

Vogmeting

Onderstam vs grondtipe vs kultivar

Basiese beginsels riglyne by die snoei van pruimbome

Ken die groeiwyse van die kultivar

Is dit n spoordraer of dra dit ook op eenjarige lote?

Is die kultivar geneig tot uitsterwing/"extinction"?

Is dit n geil of minder geil groeier?

Is dit n kultivar wat geneig is tot siektes?

Wat is die inherente grootte van die vrug van die kultivar?

Wat is die dragpotensiaal van die kultivar? Wees bewus van die beperkinge van jou gebied, klimaat, koue-eenhede en grond

Watter opleistelsel gaan jy gebruik?

Watter onderstam is gebruik?

Neem elke jaar rekords en bou data op.

There is very little one can do about thelast front of attack; last instar larvae andpupae in the soil. Nothing is registered tocombat the latter two stages and not muchis known about potential fungal infections.

We are getting to a point where this stagewill be an important part of the control ofFCM; entomopathogenic nematodes forinstance could have a major impact. Antsare often underestimated as a FCM andFruit Fly predator, said Labuschagne.

Sanitation is arguably the most importantaspect of a successful FCM managementprogramme, according to Labuschagne,who added that you have to controlalternative hosts and sanitise, thats wherethe next generation FCM comes from.

Our whole philosophy shouldbe population management and

not damage control.

Become a Pruning Connoisseur

"KNOWgrowth habit of a plant, - thesewere pruning expert Gielie Besters openingwords to growers attending the 2016HORTGRO Science technical symposiumstone fruit eld day.

Brandishing a brand new pair of pruningshears, the relatively short man with a cropof white hair, ushered the group of around30 to a Purple Majesty plum orchard at theAlle Bleue farm in Simondium.

Bester said that in trying to get a grip ofa cultivars growth habit it was importantto understand that presently there weremany cultivars released and that they allhad dierent growth patterns. Every time

a new cultivar is released, you will haveto do some research. Only after the thirdor fourth year would the grower beginto discover or understand the cultivar,according to Bester.

He suggested that growers also considerconsulting technical advisors on what theactual growth habit of the cultivar wasand listed a few important questions: Isit apical dominant? Is it basal dominant?Can the plant be bent?

When approaching Purple Majesty from apruning perspective and as a grower Bester

asks himself three important questionsirrespective of what the shoots look like.

Firstly, is the tree bearing fruit? Bestersaid that one of the cultivars problems wasthat it did not produce its full tonnage. Headvised that growers had little to benetby pruning the tree into oblivion whilethe tree was not producing fruit.

Secondly, is fruit size adequate? Bestersaid that growers often struggled with fruitsize with Purple Majesty and highlightedthe importance of keeping annual recordsand building data.

Know the fruit size thatthe cultivar is giving you

each year, because this willdetermine how to prune the

tree, he said.

Thirdly, Bester raised the issue of sugars.There is no point in having 30 tons on thetree but the sugar level in the fruit is belowthe specication for the specic cultivar tomake export possible.

PICTURE

LEFT:PruningConnoisseurGielie Bester(Capespan).

SUMMARY REPORT CONTRIBUTORS: Dane McDonald, Engela Duvenage, Jorisna Bonthuys,

Est Beerwinkel, and Elise-Marie Steenkamp.


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THE DAAN STRYDOM AWARD

This year the award for Best Fourth Year Horticulture Student went to Trevan Flynn (photo belowleft). Trevan is currently in the United States and received his prize in absentia.

Pictured below right, Stephen Rabe (HORTGRO Science Advisory Council Chair) hands over the prizeto Dr Lynn Homan from Stellenbosch University. Prof Daan Strydom, after whom the prize wasnamed, shares in the moment.

NETWORKING SYMPOSIUM STYLE

FIELD DAYS

Pictured left is Graeme Krige (Technical Advisor)

and Dr Xolani Siboza (HORTGRO Science Applied

Researcher) at the Oak Valley Field Day site.

Die manne het geluister en geleer. Tobie van Rooyen (middel) verduidelik

boordpraktyke.

Xolani aan die woord.

NEW ERA GROWER DAY

ABOVE: Sheila Storey (Nemlab), Jacky Goliath (De Fynne),

Henry Allies and Len van der Walt (Nemlab).

ABOVE: Sewis van der H orst, Adam Mouton, Kevin Maart (DFDC), Jacob Coetzee and

Theo van Rooyen.

LEFT: Gerald Swanepoel (Western Cape Department of Agriculture), Yvonne Tema

(Western Cape Department of Agriculture) and Jotta Plaatjies (Laasterivier).


23/23

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