MAINTAINING QUALITY OF FOOD AND FEED GRAIN THROUGH … · 2012-11-30 · MAINTAINING QUALITY OF FOOD AND FEED GRAIN THROUGH TRADE AND PROCESSING training manual GOOD PRACTICES FOR

MAINTAINING QUALITY OFFOOD AND FEED GRAIN

THROUGH TRADE AND PROCESSING



training manual

2GOOD PRACTICES FOR ANIMAL FEED AND LIVESTOCK

The food produced by the farmer has a long journey to travel on its way to the consumer’s plate or the animal’s feed trough. There may be a long chain through which the crop will be transported, stored and processed, with accompanying losses in quality, quantity, nutrient content and monetary value. These losses can be substantial, and if they are allowed to occur and build up, will result in a significant loss in revenue for the farmer and the end user.

This booklet describes the causes of these potential losses and illustrates actions that should be undertaken to prevent or remedy them. It assumes that grain and grain products, including flour and animal feed, have reached the first point in the marketing chain after leaving the farm. The situation of transit storage and long-term storage is considered, and millers, traders and feed compounders are also included.

The booklet is not intended to be used solely by the ultimate beneficiaries themselves, though it may well be. It is intended to be used by anyone who is involved in providing practical advice to counteract the causes of deterioration of grain and grain products along the marketing chain. These may be pest control suppliers, retailers and wholesalers, extension personnel within and outside of government, staff of trading organisations including marketing boards, and trade unions.

training manual2GOOD PRACTICES FOR ANIMAL FEED AND LIVESTOCK

Rome, 2007FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS

Peter Golob



The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. The views expressed in this information product are those of the author(s) and do not necessarily reflect the views of FAO.

ISBN 978-92-5-105853-4

All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to:ChiefElectronic Publishing Policy and Support BranchCommunication DivisionFAOViale delle Terme di Caracalla, 00153 Rome, Italy or by e-mail to:[email protected]

© FAO 2007

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Contents

Preface vAcknowledgements vii

CAUSES OF DETERIORATION 1 Loss of quality 1 Loss of quantity 2 Nutritional loss 2 Loss of seed viability 3 Commercial loss 3

FACTORS AFFECTINg qUALITy 5

CREATINg AN ENABLINg ENVIRONmENT 11 good husbandry 11 Stock management 12 Stacks 12 Inspection 14

TRANSPORTATION 17

PEST mANAgEmENT 21 Control of insect pests 21

Fumigation 21 Contact insecticides 23 Control of rodents and birds 25 Control of moulds 29

SUmmARy OF ACTIONS NEEDED 33 Hygiene and store management 33 Stock management 33 Transport 33 Pest management 33

APPENDIx Calculation for the application of contact insecticide to store walls 35

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Preface

Thegrainproducedbythefarmerhasalongjourneytotravelonitswaytotheconsumer’splateortheanimal’sfeedtrough;itmaybeprocessedintovalue-addedfoodsorfeedsforconsumptioninurbanorotherareasthatareremotefromthesiteofproduction.Theremaybealongchainthroughwhichthecropwillbetransported,storedandprocessed,withaccompanyinglossesinquality,quantity,nutrientcontentandmonetaryvalueateachstage.Iftheselossesareallowedtooccurandbuildup,therewillbeasignificantlossinrevenuefortheproducerandtheenduser.Therefore,nomatterhowmanystagesthereareinthemarketingchain,itisimportantthatgrainqualityismaintainedthroughoutthechainsothattheendproductfetchesthebestpricepossible,retainsahighnutritivevalue,andappearsattractivetobuyers.

Thisbookletdescribesthecausesofthesepotentialproblemsandillustratesactionsthat should be undertaken to prevent or remedy them. Many of the solutions do notrequiretechnicalmethodsorequipment,butdorelyonattentiontodetail,perseveranceandcommonsense.Thebookletdoesnotaddressproblemsthatcan,anddo,occuronthefarm;aseparatebookletaddresseson-farmsituations.Thisaccountassumesthatgrainandgrainproducts,includingflourandanimalfeed,havereachedthefirstpointinthemarketingchainafterleavingthefarm.Thefirstpointmaybeasmall-scaletraderwhoisbuyingdirectlyfromthefarmer,oramiddle-man.Thesituationoftransitstorageandlong-termstorage,suchaswouldoccurinhospitals,prisonsandboardingschoolsisconsidered. Millersand feedcompoundersarealso included. However, large-scalestoragesuchasbymarketingboardsandprivateexporterswhousesilosandwarehousesholdingmanythousandsoftonnesofgrainincentralstoragecomplexesisnotincluded;large scale operations require addressing in a very specific manner not appropriate tosmaller-scaleorganisations.

Oneoftheproblemsindealingwithissuesatthislevelofthemarketingchainisthatno one specific group or organisation has responsibility for providing advice to tradersandmillers.Thebookletisnotintendedtobeusedsolelybytheultimatebeneficiariesthemselves,thoughitmaywellbe. It is intendedtobeusedbyanyonewhois involvedinprovidingpracticaladvicetocounteractthecausesofdeteriorationofgrainandgrainproductsalongthemarketingchain.Thesemaybepestcontrolsuppliers,retailersandwholesalers, extension personnel within and outside of government, staff of tradingorganisationsincludingmarketingboards,andtradeunions.

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Acknowledgements

Iwould like to thank theNaturalResources InstituteUK forallowingme to reproducephotographsfromitscollection.Theinformationislargelyinthepublicdomain.Ihaveinparticularreferredtotwotextbooksforbackgroundmaterial:‘CropPost-HarvestScienceand Technology. Volume 1: Principles and Practice’ edited by Golob, P., Farrell, G andOrchard,J.E (2002),publishedbyBlackwellScience,andWorldFoodProgrammeFoodStorageManal(2003)ed.Walker,D.andFarrel,G.

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Causes of deterioration

Table 1 gRADE DEFINITIONS FOR mAIzE IN INDIA

Grade no. Maximum limit of tolerance (%)

Foreign matter Other food grains Other varieties Damaged grain Immature grain Weeviled grain

I 1.52.54.04.0

1.02.04.05.0

10.015.020.020.0

1.02.03.05.0

2.04.06.06.0

1.03.05.010.0

IIIIIIV

Note:Themoisturecontentmustnotexceed12%.Thegrainmusthaveuniformshapeandcolour.

Grain at the time of harvest may be damagedby field infestations of insect, bird and rodentspests; fungal, viral and bacterial infection; orthe ravages of flooding, high winds or drought.In essence, it is impossible to ensure that anyharvestedcropwillbeperfect.However,farmersshouldalwaysstrivetoobtainthebestcroptheycan, because this will ensure the best possiblereturn on their investments and efforts. Thisgrainwill thenbeusedtofeedthefamilyor,asisincreasinglythecase,soldforprocessingintovalue-added foods or feeds for consumption inurbanorotherareasthatareremotefromthesiteofproduction.Theremaybealongchainthroughwhich the crop will be transported, stored andprocessedbeforeitreachestheconsumer’splateorintheanimal’sfeedtrough,withaccompanyinglosses in quality, quantity, nutrient content andmonetary value at each stage. If these lossesareallowedtooccurandbuildup, therewillbea significant loss in revenue for the producerand the end user. Therefore, no matter howmany stages there are in the marketing chain,it is important that grain quality is maintainedthroughout the chain so that the end productfetches the best price possible, retains a highnutritivevalue,andappearsattractivetobuyers.Thisbookletdescribesprocessesbywhichgrainqualityandquantitycanbemaintainedthroughoutthismarketingchain.

The main causes of deterioration of grain andgrainproductsare:

• Physicalfactors:wetting,heating,breakage,discoloration, contamination with foreignmatter such as stones, rodent droppings,string;

• Biological factors: mould, insects, rodents,birds,goats;

• Humanfactors: theft,poorhandling.Physical factorsaffect foodcommoditiespar-

ticularlyduringtransportation,althoughheatandmoisturecanalsoinfluencedeteriorationduringstorage. Biological factors predominate duringstorageandhumanfactorsoccurthroughoutthemarketingchain.

Losses can be substantial and result in asignificantmarkdowninvalue. Thecommoditymay be downgraded, deemed unfit for export,andtherebyresultinasignificantlossofforeignexchangeearnings.Theremaybeaphysicallossofweight,lossofseedviability,andadecreaseinnutritive value - an important issue in much ofthedevelopingworldwherealargeproportionofthepopulationisundernourished.

LOss OF quALItyQuality is difficult to define and to measureobjectively, except in terms of monetary value.Traders and consumers purchasing or sellingin the market place usually define quality in

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subjectiveterms.However,objectiveparametersmaybeestablishedbygovernments introducinggrading methods or by similar rules developedby autonomous trading organisations such asmarketing boards, milling companies and grainexporters.Grainquality isusuallyassessedandgrades assigned on the basis of appearance,shape, size and colour, although smell anduniformity will also be relevant. An exampleof the Indian standard for maize is shown inTable1.Smallscaletradersandconsumerswilloftenassessonthebasisof fairaveragequality (FAQ), which requires no quantitative measureofparametersbutisasubjectiveassessmentofwhether the commodity meets a level which isgenerallyacceptabletoall.

Foreignmattercontentandcontaminantsarealsofactorsthataffectquality.Thesemayincluderodentdroppingsandhair,insectfragmentsandfrass, weed seeds, parts of plants, soil, stones,glass and string. Contaminants that cannot bereadily removed include urine, oils, pesticides,bacteria and viruses spread by rodents andmycotoxins. The higher the standard set by theconsumer the greater will be the potential forloss; for example, produce to be sold in urbansupermarketswillneedtoachieveahigherstan-dardthanthesameproducesoldatalocalruralmarket.

LOss OF quAntItyAtprimarysellingpointssuchasruralmarkets,grain is frequently sold by volume. This cancauseproblemswhentheunitofsaleisnotstan-dardised. For example, in Southern Africa it ispossibletofillalargejutesackwithbetween90and120kgofgraindependingonthesack’sage,asolderonescanbestretchedmoreeasilythannewones,and thereforehavegreatercapacity .Furthermore,verydrygrainwillhaveatendencytoshrinkandsooccupylessvolumeforagivenweight.It isalsonotunknownforsellerstoaddstones, dust and other extraneous matter to asacktomakeupthevolume.

Maintaining quality of food and feed grain through trade and processing

Further along the marketing chain tradingis carried out on the basis of weight. Then it isrelativelyeasytodetectlossesbutthesemaynotnecessarily be due to a loss in food value. Thelossmaybeduetoareductioninwatercontent,whichoccursduringstorageunderconditionsoflowrelativehumidity;water isgivenupbyrela-tivelywetgraintothedrierair.

Lossof foodvalue iscausedbypestdamage,insects,rodentsandbirdsfeedingongrain,orbymould,yeastandbacterialinfections.Pestattackwillresultineitherwholegrainsbeingremoved,asisfrequentlythecasewhenrodentsarepreva-lent, or parts of the grain being eaten insitu,commonlytheresultofinsectinfestations.Infec-tionsby fungiandbacteria frequentlymake thegrain unappealing and should result in grainbeingdiscardedbut,inpractice,mouldygrainisoften reserved for livestock or for brewing. It ishoweverdangerousformouldygraintobeusedin this manner as often it contains mycotoxinsthat can have severe deleterious effects on thehealthoflivestock.

nutrItIOnAL LOssWeight loss is a reflection of the overall foodloss.Nutrientlossmaybeproportionatelylargerbecause of selective feeding by pests. Rodentsandsome insectmoth larvae,e.g.Ephestia andPlodia, feed preferentially on the germ of the

FIGure 1 rodent damaged maize

Note:rodentsfeedonthegermandremovemuchoftheproteinandvitamins

3Causes of deterioration

grain,removingalargepercentageoftheproteinandvitamincontent.Weevils feedmainlyontheendosperm and reduce the carbohydrate con-tent.Manypestseatthebranofcereals,therebyreducingthevitamincontent;booklice, Liposce-lis spp., feed selectively on the germ and bran.Highmoisturecontentandtheassociatedgrowthofmicro-organismsalsoleadtochangesinvita-mincontentofgrain.Bruchids,suchasthecow-pea weevil, Callosobruchus maculatus, feed onthecotyledonsofpulsesandthe lossofproteinduetosuchinfestationisserious,asupto25%ofthedrybeanmattermaybecrudeprotein.

LOss OF seeD vIAbILItyAreductioninseedgerminationmaybecausedby changes in temperature, moisture content,excessive respiration by kernels, light, insectinfestationandbysomemethodsof insectcon-trol. Attempts to control insects by subjectinggrain to heat, either in a commercial dryer orover the kitchen fire in a farm may well affectthe germination capability. This will not matterif the grain is designated for food or feed butwill ifsomeof it isearmarkedforseed. Insectsandrodentsthatselectivelyattackthegermwillcauseagreaterlossofgerminationpotential.

COMMerCIAL LOssThis may occur as a direct consequence ofthe above, or indirectly as the cost of remedialmeasures required, for example the fumigationof insect damaged grain. Downgrading may berequired and this will reduce the price to theseller;grainmaybethendesignatedforanimalfeed rather than for human food. Commerciallosses may be expressed in terms of monetaryloss, a loss of goodwill, and loss due to legalaction. Commercial losses may affect inter-countrytrade: forexample,afteranoutbreakofthe destructive maize pest Prostephanus trun-catus in Tanzania, Malawi and Somalia refusedtoacceptTanzanianmaizebecauseoftheriskoftheinsectspreadingtotheircountries.

Theselossesoccurthroughoutthemarketingchain. The following sections examine how andwhy they occur, and identify methods by whichtheycanbereducedandqualityandvaluemain-tained.

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Themaintenanceofqualityoffoodorfeedcom-modities depends upon the same principlesand practices whether the quantities be small,perhapsa few tonnes,orwhethernational foodreserves are to be considered. The suggestionsand recommendations described will focus onquantitiesthatmightbestoredbysmalltomedi-um traders or millers, lots of up to 100tonnes,but will be applicable whatever quantities areheld.

Thefollowingfactorswillinfluenceactionsthatmightbenecessarytotake.

• The type of material beingstored,whetheritiscereal,pulseoroilseed;entiregrainormilledproducts;

• The end use of the commodity, whether itbe for animal feed or food for human con-sumption;commoditiesforlocalornationalconsumptionorforexport;

• The duration of storage, i.e. transit, medi-um-orlong-term;

• The climatic conditions to which the com-modity was exposed before receipt; whatconditions are likely to occur whilst com-moditiesareheldinstorage;

• Whatpest management practices havebeenputintoplacebeforereceipt;thecostbenefitofpestcontrol;whatpestcontrolmaterialsand equipment are available; what trainingin pest management have staff received;whatpestcontrolservicesare locallyavail-ableandtheircost.

the type of commodity will determine whichinsect pests are likely to be present. Wholecereal grains, such as maize, wheat, rice andsorghumwillbeatriskparticularlyfromweevils,including Sitophilus zeamais and S. oryzae, themaizeandriceweevilrespectively,andinAfricaandSouthAmerica fromthe largergrainborer,Prostephanustruncatus. Small grains will also

Factors affecting quality

be at risk from the lesser grain borer, Rhyzop-erthadominica.FlourbeetlessuchasTriboliumcastaneum, theredflourbeetle,infestflourandgrainproductsandaregenerallynotassociatedwithentiregrainunlessithassustainedphysicaldamageandiscrackedorsplit.Moths,includingCadracautellaand PlodiaandEphestiaspecies,also cause problems to milled grain and grainproducts.Figure2illustratessomeofthemajorinsect pests of stored grain and grain productsfoundinthetropicsandsub-tropics.

Pulses, beans, cowpea, gram, lentils etc. areattacked by a group of insects known as bru-chids.Unlikethecerealpests,whichdonot dis-criminatebetweenhost type - themaizeweevilwill quite happily attack and develop on wheat–bruchidsarequitespecificintheirhostrange.Acanthoscelides obtectus, the bean beetle, willonly develop on the common bean and othermembers of the Phaseolus family. Callosobru-chusmaculatus,thecowpeaweevil,willdevelopon cowpea and some grams but not on beans.GroundnutsinWestAfricaareatriskfromCary-donserratus, thegroundnutbeetlebutnowhereelseintheworld.

The varietal type will also influence qual-itymaintenance.Somevarietiesaremuchmoresusceptible to insect pests than others. Manysoft hybrid maize varieties are extremely sus-ceptible to insects and could lose up to 25% oftheirweightinjustafewmonthsinstoreiftheyarenotprotectedwithinsecticides.Othermaizevarieties,especiallythosethatoriginatethroughlinesgrowntraditionallybyfarmersmaywellberelatively resistant to insectpestsandonly lose1-2% by weight in a six-month period in store.Furthermore, grain that is unthreshed, suchas paddy rice and groundnut in shell, is much

�

FIGure 2

Acanthoscelides obtectus bean beetle

Callosobruchus maculatus cowpea beetle

sitophilus sp. weevils trogoderma granarium Khapra beetle, larva and adult

tribolium castaneum red flour beetle

ephestia sp. tropical warehouse moth

some common tropical and sub-tropical storage insect pests of grain and grain products


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less susceptible to insects than threshed grain,white or brown rice and groundnut kernels orredskins.

Milled commodities do not keep as well asintact grain. Flours, which consist of relativelyfinelydividedparticles,areabletoabsorbwaterfrom the air much more readily than wholegrains. They are then prone to infection byAspergillus and Penicillium moulds, which areable to produce mycotoxins such as aflatoxinandochratoxin.Furthermore,thesefinelydividedflourparticlesaremuchmoreeasilyoxidisedbyoxygen in the air. This is particularly importantin feedthathasahigh fatcontent,suchas fishmealorcottonseedcake,asthefatisconvertedintofreefattyacidsproducingrancidandnoxiousodours.Therefore, toavoid theseproblems it isimportantnottostorefinishedflourandfeedforlongperiods.

the end use of thecommoditywillalsoinflu-ence how it is managed in store. Commoditiesthataredesignatedforanimalfeedaregenerallyof inferior quality to that used for human food.Thisshouldnotbe thecaseas livestock thriveson good quality feed although it can toleratefeed of poorer quality. However, frequently thisattitude leads to livestock being given poor ifnottoxicfeed,whichmaythensuffertheconse-quencesofdiseaseandperhapsdeath. It isnotuncommon,forexample,formouldygraintobedown-gradedforanimalfeedwhenitreallyoughtto be discarded and destroyed; sometimes it isused in brewing. A classic example of animalssufferingfrominferiorfeedwasdemonstratedintheUK in the1960swhenthousandsof turkeysdiedasaresultofeatingaflatoxincontaminatedgroundnutmeal.

Commodities that are designated for exportrequireahigherlevelofmanagementthanthoseto be sold internally. Importing countries andorganisations, such as the European Union, laydown stringent restrictions on imported foodcommodities. For example, to export cereals totheEUthegrainmusthavelessthan2 µg/kgof

aflatoxinB1,lessthan1mg/kgoftheinsecticidedeltamethrin and less than 0.03 mg/kg of thefungicide imazalil. Many countries will requireimports to be accompanied by a phytosanitarycertificate,whichguaranteesthatthecommodityis freeof live insects, containsonlyaminimumof foreign matter and has chemical residuesbelow specified limits. If these conditions arenotadheredtotheconsignmentmayberejectedor the exporters may be forced to fumigate theconsignment at their own expense. It is essen-tial, therefore, that commodities designated forexportremainfreefromallcontamination.

Grain that is only in transit, perhaps in storefor up to a month or so, will not be subject tothe same infestation pressure as grain to bekept for six months or more. the duration of storage will, therefore, influence the degrada-tion of the commodity and what managementpractices will be needed to rectify any potentialproblems.Thelifecycleofinsectpestspeciesinthetropicsandsub-tropicstakesaboutamonth.Ifthecommodityisonlytobestoredforashortperiod and is uninfested or very lightly infestedon intake, it would not be economic to under-takeanypestcontrolwhilstitremainsintransit.However,insixmonthsthisverylightinfestationcould become severe. Then it will be necessaryto undertake fumigation and/or spraying withcontactinsecticidetorestrictthedamage.

Climatewillplayaveryimportantroleindeter-mining what happens to a commodity in store.In hot, humid conditions food commodities willdeteriorate rapidly. Moulds require the relativehumidity to be above 80% for optimum growthand for insects this is 70%. For both types oforganisms,increasesintemperatureto27-32°Cwill enable the maximum rate of reproductionto be achieved and so maximise the damagethat they can inflict. Good storage conditions inhighhumiditiesare verydifficult toachieveandtoenablecommoditiestobekeptformorethana month will require artificial aeration, ventila-tionsystemsorrefrigeration,methodsgenerally


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unavailableortooexpensiveforsmalltomediumtraderenterprisesinthedevelopingworld.Simi-larly,methodstoreducetemperaturesinstoresarealsodifficulttoputintopractice.Asaresult,in the tropics it isnotpossible tokeepgrainorgrainproductsforverylonginonelocation,andthecommoditymustpassrapidlyalongthemar-ketingchainsothattheconsumerhasaccesstoagoodqualityproduct.

In areas where the relative humidity is lessthan 70% problems created by moulds andinsectsarenotassevere,althoughsomespeciesareadaptedtotheselessoptimalconditions.Forexample,theKhaprabeetle,Trogodermagrana-rium,developsbestat35°Cand isabletogrowata relativehumidityas lowas2%.Thisbeetlepest isparticularlyprevalent intheMiddleEast,Asia and Africa and is a proscribed, quarantin-ablepestwherefoundoutsideitsnormalrange.Itgoesintodiapauseinadverseconditionsandsoisextremelydifficulttocontrolwithinsecticides.

Generally, it ispossibletostoregrainforlon-ger periods in dryer conditions without fear ofdeteriorationandit ispossibleforthisperiodtobeextendedforaslongastwoyearswithappro-priatemanagement.Nevertheless,pestsarestillable to operate in dryer, cooler climes so thatgoodmanagementneedstobemaintained.

At intake, grains will often be infested withinsects or may even show signs of mould con-tamination. Mouldy grain may need to be driedinordertopreventthemouldfromspreading.Ifinsectsarepresentthenthegrainmaynothavebeen treated with insecticide, the effects of thetreatment may have worn off over time, or thetreatmentwasineffective(itmayhavebeenbadlyapplied;itmayhavebeenoldandunderstrength;itmayhavebeenfake).Ifinsectsareabsentitisessential to know whether the commodity hasbeen treated before receipt so that duplicationof treatmentcanbeavoided. Itmaybe that theconsignmenthasnotbeentreatedbutthatprevi-ousgoodmanagementhasenabledittobekept

free of pests. Even if this is the case it cannotbe guaranteed that even with continued goodmanagement it will remain pest free withouttreatment.

It isthereforeessentialtoapplytheappropri-ate pest management initiatives to fit the cir-cumstances. Disinfestation is best achieved byfumigation with phosphine gas. This treatmenthas the advantage of requiring very little appli-cation equipment but, to be effective and safe,knowledgeofthecorrectproceduresisessential.Thustrainedpersonnelonlyshouldbeallowedtoconductfumigation.

Treatmentstoprotectgrainagainstinfestationcanbeachievedwithliquidcontactinsecticides.However, these need to be applied to the grainwithasprayerand,onceasackhasbeenfilled,aredifficult toapplywithoutemptying thesack.Sprayapplicationstosacksurfacesarenotrec-ommendedbecause insectscanpenetratesackfabricveryquicklyandavoidpickingupa lethaldoseoftheprotectant.Becauseoftheawkward-ness of using liquid protectants the trader maychose,instead,tofumigateatregularintervalstokeeptheinfestationpressureatnegligiblelevels.This works where large quantities of grain orgrainproductsaretobestoredforlongperiods,but for short periods and with small quantitiesthismaybeuneconomic.

Ifthetraderormillerdoesnothavetheexper-tise to carry out pest control operations, thereare usually private sector companies availableto fill this role. Using such expertise increasesthecostofstorageandmaynotguarantee thatgood practice is implemented. There are manycharlatans involved in the pest control industryand it isnotuncommonfor themtounderdose,use the wrong chemicals, apply the chemicalswith inappropriate equipment or even not treatthegrainatall.InsouthernTanzaniaithasbeenknowforacompanytocarryouta‘fumigation’bysprayingonly theoutsidesurfacesofastackofbags,andthenthespraycontainednoinsecticidebutjustwater!


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Ithasbeencommonpracticetospraythewallsand floor of stores with contact insecticides toprovideresidualprotectionagainstinsects.How-ever, in most environments in the tropics andsub-tropicssuchtreatmentsonlypersistfortwoweeksorsoandwouldthenhavetoberepeated.Thiswouldnotbecosteffectiveandsuchprac-tices are no longer recommended. However, ifthe conventional insecticide is replaced with adiatomaceousearth (DE), thepersistencyof thetreatmentismuchlongerandmuchmoreeffec-tive.ItisstillveryuncommonforDEstobeused

in this way as they are not widely available andtheyarenoteasytoapply.

Before applying pest control procedures thestore owner must estimate the cost-benefit ofthe treatment. Decisions regarding treatmentmust take into account the equipment neededand the level of competence of the staff whowouldundertaketheprocedures.Asalastresort,if external contractors are employed they mustadhererigidlytorequirementsandspecificationsestablishedbythestoreormillowner.


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GOOD husbAnDryThe essence of minimising losses is to ensurethattherailwagon,truck,storeormillarecleanand in good condition. It is essential that goodhygieneispractisedand‘equipment’wellmain-tained.

Dirtanddusthelppeststosurvive.Theypro-vide food for insects and rodents, and becausethey absorb moisture from the air they cancausethemoisturecontentofgrainandfeedtoincreaseandleadtomouldandmycotoxindevel-opment.Dirtanddustwillalsointerferewiththeactionofanypestcontroltreatmentandinpar-ticular,willreducetheeffectivenessofanysolidformulationsofinsecticidethatareapplied.

Sothetruck,containerorstoremustbesweptregularly. But this is not enough. Pests hide inplaces that are difficult to access. They live inheapsofemptysacksorinpilesofold,disusedboxesandsimilarcontainers.Ratsoftenhideinrubbish, which accumulates against the wallsofstores,eitherinsideoroutsidethestore(Fig-ure3).Theyalsohideatthebackofgrainstacks,especiallyifthesacksareleaningagainstorareclosetoawall.

Creating an enabling environment

sacks piled up against store make excellent harbourages for rodents and insects

FIGure 3

It is therefore absolutely essential that theseobstructionsareremovedfromaroundthestoreand fromsidingswhererail trucksare left.Thegroundmustbekeptfreeofvegetation.Heapsofempty sacks should be removed from the maingrainor feedstoreandkept inaseparatearea,asshouldpesticidesand tools. If sackshave tobestoredinthemainstoretheyshouldbemovedfrequentlyso that theareacanbecleaned.Anyrubbishthatcollectsmustberemovedandburnt,buriedortakenawayfordisposal.

Cleanliness will be helped if the store is ingoodcondition.Abadlyrepairedandmaintainedstoreorfreightcontainerwillleakwhenitrainsand may result in the grain becoming wet andthenmouldy. Ifrainenteringastorecomesintocontactwithaluminiumphosphidetabletsduringa fumigation it isquitepossible that the tabletswill ignite and cause a fire. An accident of thisnature occurred in Mpanda in Tanzania in 1985whenhalfof thestorebuilding fabric (concrete)and many thousands of tons of maize and cas-savathatwerebeingfumigatedweredestroyed.

Holesinthewallsanddoorswillallowrodentsand birds to enter. Cracks and crevices in thefabricofbuildingswillallowdusttoaccumulateand will provide harbourages for insects. Wallsandfloorsmustberepairedormadegoodwherenecessary. Trucks must not be permitted to bedriven inside a store if the floor has not beendesignedto taketheweightas itwillcrackandbreakup.

Machinery in flour and feed mills must bekeptsweptandbrushedregularlyandroutinely.At frequent intervals, areas in buildings mustbe cleaned to remove waste from machinery,especiallywhereaccessisdifficult.Flourbeetles,whichfeedespeciallyonmilledcerealproducts,are able to hide and accumulate in and aroundmilling machinery, conveyors and hoppers that

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arenoteasilyinspectedandcleaned.Wherethisis the case it may be necessary to shut downthe building for a period to carry out a wholebuilding fumigation. This will necessitate eithercompletelyenclosingthebuildingwithinafumi-gationsheet,possibleifthebuildingissmall,ormorecommonly,sealingitsothatitisgastight.Sealingdoors,windowsandventilatorstomakethe building gas tight is usually very difficult toachieve,especiallyindevelopingcountieswherethemillhasnotbeenpurposebuilt.Itisusuallymoreappropriate toclean thebuildingas thor-oughly as possible and then to spray the fabricwith a synthetic contact insecticide; any com-modity, flour or feed, can then be treated quiteseparately.

Open trucks and rail wagons should be cov-eredwithtarpaulinswhencarryinggrainorgrainproducts to prevent wetting by rain, access bypestsandtheft.

New sacks are often reserved for high qual-ity products such as coffee and cocoa, whereassecond-handsacksareusedforcarryingcereals,pulses and animal feed. Sacks may be reusedseveral timesandwitheachoccasionthefabricdeteriorates further.Wovenpolypropylenesacksareparticularlyvulnerableandshouldnotbeusedmorethanthreetimes.Sacksshouldberepaired,and stitched as necessary between use. Emptysackscanalsoprovidehidingplacesfor insects

FIGure 4 badly broken floor allows dust and insects to accumulate

andshouldbefumigated,sprayedwithacontactinsecticide spray or boiled in water before use.Boilingsacksisconvenientwhensmallnumbersare involved, perhaps an amount that would behandledbyasmalltrader.Thismethodischeapandenvironmentallyneutral–assumingthereisnoshortageofwater–butthesackswillneedtodrythoroughlybeforeuse.

stOCK MAnAGeMent stacksStore keepers must be able to make plans anddecisions regarding the management practicestobeintroducedintothestore,millorgodown.Toachievethisitisessentialthatthequalityofthecommoditiesbecontinuallyassessedbyinspect-ingthematregularintervals.Inspectionwillonlybeeffective if there isaccesstoasmuchof thestockasispossible.Ofcourse,itisnotpracticaltobreakdownstacks toscrutinisebagskept inthemiddleofthestack,butitshouldbepossibletoviewthecommodityatallsidesofastackandintheuppermostlayers.

Bag stacks should be built 1 m clear of allwalls,buttressesandroofsupports.Ifmorethanonestackisbuiltthegapbetweenstacksshouldalsobe1m.Thetopsofstacksshouldbeclearoftheroofandroofsupportssothatitispossibleforapersontopasseasilyaroundallsidesandoverthetopofeachstack.Thisspaceisessentialnotonlyforinspectionbutalsoforfumigationorotherpestcontrolwork.

Grain and grain products in jute, hessian orwovenpolypropylenesacksshouldnotbestackeddirectlyonthefloor.Theyshouldbestackedonamoisture-prooffloorcovering,suchaspolythenesheeting, or on dunnage such as wooden pal-lets,polesortimber.Stacksmustbebuilt inanorderly manner that allows inspection. Badlybuiltstacks,oronesthataretoohigh,maycol-lapseand injurepeople,causingdamage to thecommodityortothefabricofthestore(Figure5).Stacking against walls will prevent inspectionandmaycausestructuraldamage to thewalls.


13

FIGure 8 Choosing a stack pattern

Layer I

6-bag pattern 8-bag pattern 10-bag pattern

Layer IILayer IILayer II

Layer ILayer I

Tobebuiltsafely,highstacksmusthaveasuf-ficientlylargenumberofbagstobestacked;thestackmustbewellbonded.Themorebagsthereareinastackingpatternthebettershouldbethebondingandstability.

Themainfactorsthatinfluencethechoiceofastackingpatternare:

• Heightofthestack• Easeofdismantling• Ratiooflengthtowidthofbags• Materialthebagsaremadeof(fibre,paper,

WPP)A stacking pattern with great stability is one

in which each bag in each layer is bonded intoneighbouringbagssothattherearenocontinu-ousverticalsacksordivisionsbetweensacks.

The pattern chosen will be a compromise

Stacks incontactwiththeroofmaycausesolarheattobetransmittedtothecommodity.

Stacksmaybebuiltup inmanydifferentpat-terns (Figure6).Largerstacks,whicharecom-pletelybonded,mayutilise thebasic3or5bagdesignasshowninFigure7.Smallerstacksarebetterconstructedwithalargerbasicunitof8or10bagsasshowninFigure8.Thepatternusedtoconstructthestackwillbedeterminedbythesizeof the sacks themselves, especially the ratio oflengthtowidth,theoverallstabilityrequiredandeaseofdismantling(Figure9).Stacksbuiltwitha3-bagbasicunitwillbequicktodismantle;onesidecanberemovedwhilstleavingtheremainderintact,butarerelativelyunstable.


FIGure 5 high stacks

TOO NARROWNO BONDING

SIDEBONDED AND SAFE

TOP VIEW

FIGure 6 Main factors in choosing a stacking pattern

HEIGHT

FIBRE

LENGTH: WIDTHOF BAG

DISMANTLING

MATERIALS OF BAGS

PAPER WOVENPLASTIC

FIGure 7 One type of continuous bonded stack pattern

Layer I Layer II

SIDE

Layer III

14

FIGure 9 special stacking patterns

Bags of 3:2 ratio

5-bag pattern

Layer I Layer I

Layer II Layer II

4-bag pattern

For drying or cooling

betweensafetyandconvenienceinstackinganddismantling.To increasesafety,patternsof6,8or10bagscanbeused,butonlyiftheratioofbaglengthtowidthis2:1.

Iftheratioofthelengthtowidthofthebagsis3:2(not2:1)thenthe5–bagpatterncanbeused.If the bag requires cooling or drying then the 4–bagpatternwillbebetter.

Paper and polypropylene sacks are more dif-ficult tostackproperly than jutesacksbecausethereislessfrictionbetweenthem.Cornersarethe least stable areas of stacks and care mustbetakentoensuretheyaresafe.Itisbetternotto have vertical sides but rather to have sidessloping inwards from the base upwards, thisimprovesstability.Suchadesignwillalsofacili-tateaccesstothetopofthestack.

Ifspaceallows, it isbettertokeepcommodi-tiesseparatedindifferentstacks,asitistokeepdifferenttypesofsacksorcontainersseparated.

InspectionThepurposeofinspectionistogatherinforma-tionaboutthestoreanditscontentssothatdeci-sionscanbemaderegardingproceduresneededfor quality maintenance. In essence, inspectingwillallowthestorekeepertodecideifandwhento carry out pest control. It will also make themanagerawareoftheprogressofthecommod-

ity whilst in store, and its shelf life. Inspectionmust be accompanied by effective record keep-ingso that thehistoryof thecommoditycanbefollowed. Record keeping will inform the store-keeperofwhenthecommoditywasreceivedandwhatpestmanagementpracticeshavebeencar-riedout.Recordcardsmustbeattacheddirectlytothestacktoavoidanypossibleambiguity.Itisgoodpractisetokeeparecordcardeven ifonlyonesmallstackisinstoreasthiswillenabletheownertorememberdetailsaboutthecommod-ity.Figure10showsanexampleofastackrecordcardandinspectionreport.

Inspections must be done regularly and notlessthanonceaweek,irrespectiveofthesizeofthestoreorofitscontents.Theyshouldincludea complete walk around the store both insideand outside, around the stock, including foodandnon-food items.Whereappropriate,a torchshouldbeusedtoexaminedarkareasandthosein shadow, gaps between stacks and betweenbags.

Theinspectormustlookcarefullyfor:• signs of pest infestation, including live

insects, rodent droppings, rodent urinetrails;

• dampness;• moulddamage;• spillage;• contamination of sacks by foreign matter

suchasoil,fertiliser,pesticide;

FIGure 10 stack record card

Date

Date

On reverse side

Treatment given By whom

In Out Balance Signature

Stack No.:

Commodity:


15

• roofleaksandotherstructuralfaults;• theftorothersecurityproblems.Insects accumulate in cracks and crevices,

along sack stitching and where sack surfacesmake contact. If the presence of insects issuspected in a sack this can be confirmed byagitating the bag, when adults will move to theupper surfaces. If the storekeeper has accessto a sampling spear, this can be used to col-lect samples from a number of sacks to checkwhether insects are present. The condition ofpestcontrolmeasuressuchasrodentbaittrapsandproofingwhichmightbedisturbedby load-ingandunloading,shouldbenotedandrectifiedif necessary. Assessments of fumigation and/orcontact insecticide application should be made.Anystructuraldamageshouldbemadegoodassoonaspossible.

Rodentscanleavemanydifferentsignsoftheirpresence. Many species prefer to use familiar,

safe routes when moving around so that theyrepeatedly run across the same ground com-pactingitandleavingitdust-free.Astheymoverodents leave behind greasy smears from theirfurastheybrushagainstsurfaces.Thedamagecaused by biting can also be easily recognised;rodents tend to remove the germ from maizesocreatingahalf-moonshapedcavity inmaizegrain.Similarly,burrowsorholesarealsoindica-tiveofrodentsgainingaccesstoparticularareas.Rodenturinecanbeoftenspottedwhenitformspillars as the animals frequently urinate onthesamespot.Thepresenceof rodentscanbedetectedbyfootprints left ina finesprinklingofflour over the sack surfaces. Perhaps the mostreliable and simplest way to detect their pres-enceistolookfordroppings.Figure11illustratessomeofthesignstolookforwheninspectingforrodents.


1�

damagetocable

FIGure 11 signs of the presence of rodents

urinepillars

damagedsack

footprints damagetostructures

droppings damagedbox


17

transportation

Losses that arise during transportation occurmainly due to damage to the packaging, suchastearsorripsinwovenpolypropylenesacking,resultinginspillage.Forlongerhaulcarriage,forexamplebyrailorlorrytodistantmarkets,otherproblemsmayoccurincluding:waterpenetrationor wetting and subsequent mould damage andmycotoxin contamination; insect or rodent pestinfestation;changesduetothemicro-climateasaresultofmovinggrainfromcool,highaltitudeto lowland, humid altitude; accidental contami-nation.

Care of grain must be of paramount impor-tance no matter what type of transport systemisused.Eventhelargestandmostsophisticatedmeansoftransport,suchasashipbulkcarrier,will require human intervention to make surethatgrainqualitydoesnotsufferduringthevoy-ageorjourney.

The most basic method of transport fromfarm to market is the head load. Women regu-larlycarrywater, fuelandgrainon theirheads.Althoughgrainmaywellbeexposed to theele-ments during carriage, the short duration ofjourneysmeansthatlittleifanychangeinqual-ity is experienced. However, if this head load isinterspersed with travel on a bus or train thenproblemsmayoccurparticularlyduetospillage.

Lessarduousmethodsofdeliveringgrainfromthe farm use animal or motor driven carts ormore.Oxenareusedinmanypartsoftheworldto pull carts, which may contain 2 tonnes ormoreofgraininsacks.Replacingtheoxenwithamotordrivenvehiclesuchasatractorwillenabletheloadtobeincreased.However,bothtypesoftransportarerelativelyslowandonlyallowshortjourneystobeundertaken.

The short journeys made in the transport sofar described do not allow time for biologicaldeteriorationtotakeplace.However,oncetrucks

FIGure 12 Woman with head load of maize cobs on the way to market

FIGure 13 Ox cart (a) and (b) motor driven cart

(a)

(b)

18

are used to transport grain, journeys can bemuch longer and the effects of pests and dis-easesmaybecomeevidentwhenthecommodityisinspectedonarrival.

Trucks transporting any grain or other foodcommoditiesmustbeclean.Theymustbesweptfree of dust and debris. Insects must be elimi-nated to ensure the new consignment is notsubjected to infestation from residual popula-tions. Bodies of trucks should be sprayed witha synthetic contact insecticide such as Actellicemulsifiableconcentrateorwettablepowder.

Loading the truckmustbedonewithenoughcaretoavoiddamagingsacks.Wovenpolypropyl-eneandpapersacksshouldnotbehandledwithhooksastheseeasilydamagethefabricresultinginspillage; it isnotgoodpracticetohandleanytypeofsackwithahook.Loadingshouldbedonemanually or using a small conveyor (Figure 14)Trucksmustbeloadedonlytotheirstatedcapac-ity as overloading will make the truck unstableand likely to tip over, a not uncommon occur-rence(Figure15).

All commodities should be accompanied bydocumentation, which records the origin of theconsignment and any pest management treat-mentthathasbeenapplied.Thisdocumentationwill be especially needed where a consignmentistocrossaninternationalborder;itislikelythatphytosanitaryandfumigationcertificateswillberequired.However,thiscertificationmayalsoberequired for internal grain movements, particu-

larlywhengrainhastobemovedintoandoutofareas of quarantine. For example, in Tanzania,an outbreak of the larger grain borer, a majorpestofstoredmaize,resultedinseveralareasofthecountrybeingquarantined,sothatallmove-mentsofmaize intooroutof theseareaswererestricted. However, other crops that were notaffectedbythispesthadtobetreatedwithinsec-ticide or fumigated, and proof of their being sowasdemandedatcheckpointsestablishedalongroads leading to the quarantined areas (Figure16).Trucksapproaching thesecheckpointswithdocumentation were stopped from entering orexiting,causingsubstantialfinancialpenaltiestotheownersofboththecommodityandthetruck.In some cases the consignments were tempo-

FIGure 14 Loading a truck

FIGure 15 Overturned truck

FIGure 16 Checkpoints for stop and search, may require examination of documents


19

rarilyconfiscatedand fumigatedbygovernmentinspectors before being released back to theownerwhoborethecostoftreatment.

Openrailwagonsshouldbetreatedinthesamewayasroadtrucks.Freightwagonsthatcanbeclosedoffcanbefumigatediftheycanbemadeairtight(Figure17).Whenempty,freightwagonsmustbethoroughlycleaned.Oncethecommodityhasbeenloaded,preferablyonpallets,tabletsofaluminium phosphide, which release phosphinegasonexposure toair, shouldbeplacedunderthe pallets and the container then sealed. Afumigationwill take7daysor longerdepending

on the temperature, during which time accessto the commodity will not be possible. Fumiga-tioncanalsobeundertakenwhenthecontainerisempty todisinfest the fabric,although this isgenerally unnecessary; it is however useful todisinfestbalesofempty,usedsacksplacedintheunloadedcontainer.

Graincarriedinfreightcontainerscanalsobefumigated whether transported by road, rail orsea.Thisisapracticethatisbecomingincreas-inglycommon,althoughthetreatmentfrequentlyfails.Failuresareduetotheleakageofgasoutofthecontainersothattheconcentrationinsideisinsufficienttokill insectpests.Mostcontainers,likerailwagons,haveventilationopenings.Thesemaybelocatedatthetopofthewalls,sometimesintheroof,andmoreofteninthefloor.Forasuc-cessful fumigation these ventilators have to besealed topreventgas leakage.Thismaybedif-ficult toachieve,especially if theventilatorsaredifficult toaccess,eitherbecause thecontaineris full or because their position under the floormakestheminaccessible.Ifthecontainercannotbe adequately sealed, fumigation should not beattemptedastodosowouldbedangerous-per-sonnelwouldbeatriskfromescapinggas–andineffective because insects would not receive afataldose.

FIGure 17 Freight containers can be fumigated if they can be made gas tight. sealing end ventilators on this container will be difficult

transportation

21

Preventing lossesfromoccurring isalwaysbet-terthanhavingto introduceremedialmeasuresafterwards. However, the trader or storekeepermustdecidewhetheritiscost-effectivetounder-take precautionary measures. This will dependonthetypeofcommoditytobestored,itsintrin-sicvalue,andtheperiodforwhichitwillremaininstore.However,eventhoughagrainconsign-mentmightonlybeintransitandinstorageforafewweeks,successivedeliveriesanddespatchesofgrainmaywellrequireprophylactictreatmentsbe undertaken to ensure that none of the con-signmentisputatrisk.Inareasofhighhumidity,suchasinmuchofSouthEastAsia,insectdevel-opmentcanbeveryrapidanditisnotuncommonfor overwhelming populations of Psochidea orbooklicetoappearinamatterofafewweeks.

Goodhygieneandstoremaintenancearepre-requisites for employing measures to preventlosses from occurring. Pest control measureswill fail if the store is dirty or in poor condition(Figure18).Anotheressentialistoensureahighlevelofstoreandstockmanagement.Inaclean,well-managed store pest control practices canbeeasilyemployed.Thisisveryoftennotthecaseif the stock is not well stacked; if bicycles arerepaired in thestore; ifmetaldrums,oldsacksandpesticidecontainersare lefthaphazardly; ifspiltgrainisnotsweptup;ifthestoreisusedasameetingplaceorcafé.

COntrOL OF InseCt Pests FumigationGrainandgrainproductscanbeprotectedagainststorageinsectpestdamagebyeliminatingexist-ingpopulations, i.e.bydisinfestation,orbypre-venting infestation occurring in the first place.Fumigant gases are used for disinfestation andcontact insecticides are used as protectants topreventinfestations.

Fumigationisachievedbytheactionofagas,phosphine, which is released from aluminiumphosphideormagnesiumphosphidewhenthesecomeintocontactwithmoistureintheair.Phos-phine is extremely poisonous to insects, manand animals, and so very great care must betakenwhen it isused.Fumigationmustonlybeundertakenbytrainedpersonnel.

Fumigationmusttakeplaceinsideagas-tightcontainer or enclosure. This can be a metal orplasticstructuresuchasa20or40tonnefreightcontainer,a3-4 tonnehighdensitypolytank,ora sealable 200 litre oil drum. Most commonly,fumigationsarecarriedoutinfoodstoresundera non-porous fumigation sheet, which is helddownontothefloorwith‘sandsnakes’,longnar-rowtubesofcottonclothorsimilarmaterialfilledwithsand.Theweightofthesandsnakeskeepsthesheetflatonthefloorandpreventsgasleak-age(Figure19).

If the container or enclosure is not gas-tightphosphinewillescapeintotheenvironmentandbeahazardtopeopleandlivestockinthevicin-ity.Gas leakagewillalsoresult inan ineffective

Pest management

FIGure 18 example of a badly managed store in which it is impossible to undertake pest management procedures

22

fumigationasphosphinewillnotbeinsufficientconcentrationlongenoughtokillalltheinsectsin the commodity. If insects survive they maybecome resistant to the gas so that in future,even when good quality fumigations are under-taken,theymaynotbefullyeffective.

Someofthecommercialformulationsofphos-phineareshowninTable2below.Ofthese,tab-letsofaluminiumphosphide,whichrelease1gofphosphine,areinmostcommonuseingrainandfeedstoresinthetropicsandsub-tropics.Pelletsareusefulfordisinfectingindividualsacks.

Once a bag stack has been properly coveredwithafumigationsheetthetabletsareintroducedunderthesheet,whichisthenresealed.Tabletscanbeputinsideasmallpaperenvelopeorpieceofcottoncloth.Theymustbespreadoutaroundthestack,nomorethansixtabletsinonelot.The

FIGure 19 Measuring phosphine gas concentration in stack covered with thick polythene sheeting and anchored to ground with sand snakes

Formulation unit weight (g) Phosphine released (g)

Pellets 0.6 0.2

Tablets 3.0 1.0

Minibags 9.0 3.0

Bag(sachet) 34.0 11.3

Bag(sachet)withstringsorchains 340.0 113.0

Blanket 3,400.0 1,130.0

Plates 117.0 33.0

applicationrateis3-5tabletsforeverytonneofgrainorcubicmetreofstorevolume(Table3).Itiseasiercalculatingthedosageontheweightofgraintobetreatedifthestackisunderasheet.Ifthegrainisinapolytankormetalcontainerthedosageshouldbecalculatedonthevolumetobetreated,itshouldbethesamewhetherthetankiscompletelyfull,halffullornearlyempty.

Fumigationwithphosphine takesaminimumof seven days to complete whatever type ofcontainer or enclosure is used (Table 4). If thefumigation is ended after a shorter period it isvery likely that some insects will survive, thetreatmentwillbeafailureandwillprobablyneedtoberepeated.

Once a fumigation is complete the stack orcontainer must be fully aired to blow off anyremaining gas before the trader can take theproduceaway.Airingisashortprocessthatcanbecompletedin2–8hoursdependingonthesizeof the stack. By the end of the fumigation, thealuminiumphosphidetabletswillhavedegradedleavingagreypowder,aluminiumhydroxide.Thispowder must be stirred into a bucket of waterandthenpouredaway.

Individual 50 kg lots of grain or feed can beseparatelyfumigatedwhenplacedinsideasuit-able sack. The sack must have an inner poly-thenelinerofatleast500µmandasecondouterlayerof jute,hessianorwovenpolypropylenetoprotect the liner. Ideally,onceapellet isplacedinside the sack the polythene should be heatsealed. However, it is acceptable to twist and


Table 2 FORmULATIONS APPROPRIATE FOR SmALL TO mEDIUm SCALE USE

23Pest management

type of fumigation recommended dosagea

g Ph3 per tonne g Ph3 per m3

Bulkfumigationingas-tightsilos 2to4 1.5to3.0

Baggedcommoditiesundergas-proofsheets 3to5 2to3.5

In-bagfumigations 0.2gperbagb

Spacefumigations,e.g.emptystore 1.0

temperature (ºC) exposure period (days after application of the fumigant)

below15 donotuse

15to25 10

above25 7

turnthemouthofthepolytheneonitselfandtieitoffwithstring.Pelletsofaluminiumphosphide,releasing 0.2 g phosphine were designed to beusedinthismanner.

Contact insecticidesInspectionwillindicatetheneedforpestcontrolmeasures. In many storage complexes insectcontrolisconductedonaroutinecalendarbasis.Fumigationmaybecarriedouteverythreemonthsandspraying thestorewallsevery twomonths,regardless of real need. This is a costly andinefficient way to control insect pests becausefrequently, the fumigation will be applied to acommodity with no pests or because the sprayapplicationmayonlybeeffective foroneor twoweeks. It is therefore important to undertakepest control operations only when needed andthiswillbeindicatedbyinspection.

Beforeanycontroloperationsareundertakenthe store or mill areas to be treated must becleaned. Walls, floor and machinery must besweptwithbroomsandthesweepingsremoved.Immediately prior to fumigation, the internalstorefabricandanymachineryshouldbetreatedwith a contact insecticide spray to kill off any

insects that might be lurking in cracks in con-creteor inconcealedplacesaroundmachinery.This treatment isdesigned tokillat the timeofapplication,nottoprovideresidualprotection.

It is always advisable to clean and spray anempty store immediately before a new stock istobereceived.Thiswilldisinfestthebuildingofanyover-winteringinsectpests,whichotherwisecouldattackthe incomingcommodity. It isusu-ally not necessary to spray the roof fabric as itgenerallybecomestoohotduringthedaytimetosupportinsectdevelopment.However,ifthereisaceilingpresentbelowtheeavesthisshouldbetreated.

Hand-operated sprayers are convenient forsmall to medium sized stores. These may beof two types,continuouslypumpedorpre-pres-surised. The former have to be pumped by theoperator throughout the procedure (Figure 20a)but pressurised sprayers do not, and thereforerequire only one hand to operate. Pressurisedsprayers should be fitted with a self-regulatingvalve and operated at about 4 bar (4 kg/cm2).Largerareascanbecoveredwithsprayersoper-ated with petrol engines (Figure20b), includingmotorisedknapsacksprayers.Theselasttendtobeverywastefulofliquidasmuchofthesprayislostintotheairspace.

Spraysarebestappliedwithanozzleproduc-ingaflatfanpattern,althoughconepatternsarealsoacceptable.Thenozzleheadshouldbekeptabout 15 cm from the wall to provide adequatecover,buttopreventtoomuchbounceandback

Table 3 RECOmmENDED DOSAgE RATES FOR PHOSPHINE

Table 4 mINImUm ExPOSURE PERIODS RECOmmENDED USINg PHOSPHINE

24

ticides and other pesticides. Depending on thechemicalused,between0.1-1.0gofactiveingre-dient must be applied per m2, and usually theapplicationrateofthedilutedsolutiontocementsurfaces is 5 l/100 m2. The appendix providesanexampleofhowtocalculatethedilutionofacontact insecticide tobeapplied to thewallsofastore.

Freight wagons and containers should betreatedinthesamewayexceptthatlessdilutedsolution needs to be applied as the metal sur-facesdonotabsorbanyofthesolution;arateof2l/100m2isusuallysufficient.

There are several commercially-availableinsecticides that can be used for this purpose.These are broadly classified into two groups,organophosphates (OP)andpyrethroids (P) (seeBox 1). Each chemical is known by a commonname and a commercial name. Although com-mon names remain constant the commercialname changes depending on which company ismarketingtheproduct.

Someofthesechemicals,suchasdichlorvos,arehighly volatileandgiveoffa lotofchemicalvapour.Theseareparticularlyusefulforflushinginsectsoutofcracksandarealsousedforspray-ingorfoggingtheairspaceinstorestokillflyinginsectsespeciallyadultmoths.OPandPchemi-calsareoftenusedtogether tocontroldifferent

spray. Sprays should be applied until run offoccurs,asthiswillallowtheliquidtopenetrateinto cracks and crevices where insects may behiding.

Only sufficient spray solution should be pre-paredtotreattheareastobecovered.Inevitably,somedilutespraysolutionmayremainoncetheoperationiscompleted.Ifthishappenstherem-nantsofthesolutionshouldsimplybeappliedtothe walls or floor until the sprayer is emptied.Aftercompletingtheoperationthesprayermustbewashedoutthoroughlywithwater.

Contact insecticides are sold in several dif-ferent formulations. Those that are appropriatefor treating surfaces include wettable powders(wp:solidswhicharedispersedinwater),emul-sifiable concentrates (ec: liquids which are dis-persedinwatertoformanemulsion)andsolubleconcentrates(sc:liquidsdilutedinasolventsuchas oil to form a true solution). Ecs tend to bethe most commonly available and are the mostconvenient to use in hand operated sprayers.Insecticide concentrates generally contain 20-40%(somedeltamethrin formulationsonlycon-tain2.5%)active ingredientandmustbedilutedbeforeuse.

Manufacturers’recommendationsonthelabelmustbeadheredtowhenapplyingcontactinsec-

FIGure 20 hand operated pneumatic sprayer

(a) (b)


25

insects; the former are particularly effective incontrollingweevilswhilstthelatterarebetteratdealing with borers, especially the larger grainborer. Diatomaceous earths (DE) are not suit-ablefortreatingstorefabric inthiswaypriortofumigationastheirrateofactivity istooslowtoensurerapidkill;buttheycanbeusedtoprovidepersistent,residualprotection.

These chemicals, especially the organophos-phates, have high or moderately high mamma-lian toxicity, so great care must be taken whenthey are handled. Gloves must always be wornwhen handling concentrates as should otherprotective clothing, such as overalls and boots,during spraying. During any spraying operationabucketofwatermustbeclosetohandtopourover affected areas that become contaminatedaccidentally.Sprayingshouldneverbeundertak-enbyasingleperson,asecond individualmustbepresenttoensureremedialmeasuresareputinto place in case of accidents. A summary ofsafetyconsiderationsisgiveninBox2.

bOX 1

Common name

Organophosphate (OP)Pirimiphos-methyl

Chlorpyrifos-methyl

Fenitrothion

Dichlorvos

malathion

Pyrethroid (P)Permethrin

Deltamethrin

Fenvalerate

Bioresmethrin

Commercial name

Actellic

Reldan

Folithion; Sumithion;

Accothion

Nuvan; Vapona

Cythion; mLT; Agrothion

Ambush; Talcord; Eksmin

K-Othrine; Decis

Sumicidin; Fenkill;

Sumitox

Isathrine

InseCtICIDes AvAILAbLe FOr sPrAyInG surFACes

FIGure 21 A space sprayer in position on the roof lintel

FIGure 22 Fogging a store

COntrOL OF rODents AnD bIrDsStored grain and grain products must also beprotected against rodents and birds. This maybe almost impossible to achieve if doors areleft open. Even when closed, rodents may stillgainaccessiftherearegapsbetweendoorsandwalls,ifventilatorsareleftopen,throughgapsintheroofingandthroughentrypoints forcabling

Pest management

2�

All holes in the fabric of the building mustbe blocked up, either with cement or with wirenetting; the netting must be fine enough (5mm

and ducting. Similarly, birds are able to enterthrough ventilators and doorways. To prevententry, all gaps should either be filled in withcementor fittedwithwirenetting. Ifdoorshavetobeleftopentheyshouldbefittedwithametalkickplatewhichwillpreventrodentsfromgain-ingaccess;aflexiblecurtainwillkeepoutbirds.

Thusitisimportanttomanipulatetheenviron-ment to restrict access by these pests. Waterand food are essential for rodents and birdsso that by restricting availability the pests willlook elsewhere. This of course is very difficultto achieve around buildings holding grain andgrainproducts.However,itispossibletorestrictaccess by proofing, which prevents pests fromaccessingthefoodinthestoreormill.Thishastobeundertakenbymanipulatingthesurround-ings outside of the store as well as managingconditionsinside.

bOX 2

• Always read the pesticide label and follow the

instructions

• Wear clean and appropriate clothing; gloves

are essential; a face mask is advisable but if

not available a clean piece of cloth should be

tied over the mouth; boots should be worn,

trousers should be worn outside the boots; a

face shield is useful to protect eyes

• Always keep insecticides under lock and

key and when in use, never leave bottles

unattended

• Never transfer insecticides to other containers,

particularly soft drink bottles

• Never reuse insecticide containers for other

purposes; dispose of empty containers, ensure

they cannot be reused

• When working with insecticides do not eat or

drink, do not rub your eyes, do not smoke

• Keep food and drink away from insecticides

• Have plenty of soap and water available, and a

change of clothing

• Always wash after handling insecticides

• Destroy heavily contaminated clothing; after

spraying wash clothing and protective gear

• If spills occur wash the area immediately; wash

off any dribbles that might have contaminated

the outside of the insecticide container and any

vessel used for dilution

• Nobody except those involved in the insecticide

application should be allowed in the store

whilst spraying is in progress; nobody should

be allowed to handle insecticide containers

except authorised personnel

• Workers should be made to cover their feet to

prevent contamination from the floor

• The electricity supply should be turned off

before spraying begins

• Excess spray solution should be applied to the

walls or floor

FIGure 23 screening a drain pipe to prevent rodent entry

sAFe use OF COntACt InseCtICIDes


27

or less) to prevent small mice gaining accessif these are known to be present in the vicinity.Doorsmustnothavegapslargerthan5mmandifakickplateisfitteditshouldbealeast1mhightopreventratsjumpingover.Theendsofrainwa-terpipesshouldbe fittedwithmesh,anddownpipes,forrainwaterandelectricalcables,shouldbe fitted with metal baffles to prevent rodentsclimbing.Debrisandvegetationmustbeclearedaway from the sides of buildings. A trench 30cmdepthand20cmwideshouldbedugaroundthe exterior walls and filled with fine gravel. Toprevent rodents tunnelling, a concrete layer 10cm thick and extending 60 cm below ground,with the base turned out to form an Lshapefor50cmshouldbelaid.Foodspillagemustbeimmediatelyremovedandsourcesofwatereitherproofed,turnedofforremoved.

Itmaynotbefeasible,becauseofthedesignofthepremisesor their location, toput intoprac-tice all of the requirements to make a buildingrodentproof.Nevertheless, it is importanttotryasfaraspossibletoachievethisaim.Ifthestoreis adjacent to other storage buildings, such asinamarket,it isessentialthatallthestoresbetreatedtogetherbecauseifoneisleftunproofeditwillbecomeamagnetforpestsandwillfacili-tateaccesstoalltheotherstores.

Cleanlinessinsidethestore,theseparationofstacks and the removal of non-food items willassistinkeepingrodentsout.However,thismaynotbesufficienttopreventlossesanditmaybenecessarytouserodenticides.

Unlikeinsecticides,whichworksimplyoncon-tact,rodenticidesmustbeingestedtoexerttheireffect. Rodenticides fall into two main groups,acute and chronic poisons. Acute poisons havebeen in use for very many years. They kill thetarget very rapidly,perhaps inamatterofmin-utes or hours. The effect can be very dramaticastherodentdiesoutintheopenandisvisible.However, many individuals will not be affectedsothatdamageandnuisancelevelswillremainsignificant, especially as the rodent population

willquicklyrecover.Acutepoisonsmaybeofuseinrapidlyreducingapopulationsolongasmassbaiting is done. These chemicals are cheap,widelyavailableandcommonlyused.

All rodenticides must be offered in the formof a bait. It is generally useful to lay downbait before adding the rodenticide to allow therodentstofamiliarisethemselveswithsomethingnew in theirenvironment.Many rodentspecies,especially the house mouse, are neophobic,suspicious of and avoiding new objects, so theymustbeallowedtobecomeusedtoobjects.Evenwhentheybegintoeatbait,theymayonlynibbleat itandconsumeasub-lethaldose.Theacutepoison will cause unpleasant feelings that willprevent further feeding inthefuture, therodentbecoming ‘bait shy’. Pre-baiting will allow therodenttobecomefamiliarwiththebaitbutmaytake several days and even weeks with housemice.Evenso,itremainsdifficulttoachievecom-pletemortalitywithacutepoisons.

There are some compounds, sub-acute poi-sons, which are similar to acute poisons butwhere the symptoms are slower to appear. Alethal dose may therefore be consumed in sev-eralfeedingsratherthaninasinglemeal.Deathmaybedelayedforseveraldays.

Chronicpoisonsareallanticoagulants.Deathmay occur in 2-3 days but more usually in7-8days. The discomfort felt by the rodent ismuchlessthanwithacutepoisonssothatfeed-ing will continue unabated, until death occurs.However, it isnecessary toensure that thebaitis placed correctly so that it is consumed bythe rodents regularly. Therefore, care must betaken toensure that rodentsaregiven thebestopportunity to feed; thebaitmustbesitedopti-mally.Whenrodentsregularlyfeednestpartners,young and adults will be encouraged to feed inthesamelocation.Furthermore,ratslikehoard-ingandoftentakebaitbacktothenesttoeatinfamiliarsurroundings,whereothersmayshare.Inthisway,itispossibletoachieve100%killinatargetpopulation.

Pest management

28

Warfarin was the first chronic poison to bemarketed some 50 years ago. Others quicklyfollowedbutthereisnowwidespreadresistanceto most of these early, first generation chronicrodenticides.Moretoxic,secondgenerationcom-pounds have largely superseded earlier chemi-calsbutthereisincreasingevidencethatrodentsare becoming resistant to these as well. It istherefore important to ensure that the applica-tionofrodenticidesisasefficientaspossibleandiscarriedoutbyatrainedpestcontroloperator.

Thereareanumberofready-madeediblebaitsavailableincludingloosecerealsandotherfoods,pellets, wax blocks, gels and pastes. Solubleforms of rodenticide may be added to water,useful infoodstoreswherefreewatersupply isusuallyabsent.Loosebaitsareperhapsthemosteffectivebuthavetobeusedwithcareespeciallyin food storage and preparation premises. It isprobably most efficient to buy the rodenticideconcentrate and mix it in with whatever food islocallyavailableandcheap.Greatcaremustbe

takendoingthisasconcentratesarethemselveshighly toxic. Rodents are mammals like man,and any chemical toxic to rodents will also betoxictoman.

Baits can be laid directly on rodent pathwayseither loosely or placed on trays, in bait boxesor containers. The use of a closed containerwillpreventbaitbeingdisturbedinpublicareas,where people work, such as in stores or mills.In these locations it may be useful to provide asourceofwaternexttothebaitasanattractiontorodents.

Untreated baits can also be used in rodenttraps.Therearetwotypesoftrap,thosethatkillandthosethatcapture.Killtrapsare‘breakback’traps (Figure24) inwhichaspring, releasedbytheactivityof therodent, isreleasedanddrivesdown a metal bar, breaking the back of therodent. Live traps entice the rodent into a cagefrom which it cannot leave (Figure 25). Thereare many designs but all are passive, depend-ingentirelyonthebehaviouroftherodent.Manyrodents are ‘trap shy’. Traps may play a partin controlling the population in a store but it islikelytheywilllosetheirappealovertime;trapsshouldbemovedtodifferentlocationstocounterthe learning capability of rodents. Their mainadvantageisthattheyarenon-toxicandwillnotcontaminatethefoodstore.

Birds enter stores and mills to gain accessto food. Their main deterrent is to ensure thatnofoodisavailable. It isvital,therefore,thatallspillage of grain, flour or feed be swept up assoonaspossibleandtakenoutofthebuildingfordisposal.However,birdscaneasilymakeholesinsacksofgrain,flourorfeedandactionmustbetakentodeprivethemoftheopportunityofdoingso. For most small to medium sized stores themosteffectivewayofpreventingdamagebybirdsis to exclude them from the premises by fixingwirenettingoverentrypoints,forexample,ven-tilation openings. Plastic or metal curtains canalsobeaffixedtodoorwaystoprohibitbirdentry,

bOX 3

ACute

Alphachloralose

mono sodium fluoroacetate

Fluoroacetamide

Red squill (extract of plant Drimia maritima)

or purified as Silmurin

Thallium sulphate

zinc phosphide

sub-ACute

Bromethalin

Calciferol

ChrOnIC (2nD GenerAtIOn)Defenacoum

Bromodialone

Brodifacoum

Floucamfen

Difethialone

rODentICIDes


29

particularlyusefulwherethedoorhastoremainopenforlongperiods.

COntrOL OF MOuLDsFungigainaccesstograinthroughopeningscre-atedbydamageduetopoorhandling.Theygaineasieraccesstoflourandfeedasthe‘openings’are purposely produced by the milling process;finely divided foods are relatively easily invadedbyfungalspores.

Physical damage usually occurs in the fieldjust before or during harvesting, then duringthreshingandwinnowing.By the timethegrainentersthestoreitmaywellbeinfectedwithfun-galsporesorevenbyfungalmycelia,whichare

FIGure 25 rats in a live trap

rat being enticed to a break back trap by loose groundnuts

FIGure 24 recognised as mould growth. Spores germinateand moulds grow because the water activityof the host is sufficient to allow development.In humid conditions mould growth will occurquickly,lesssoindryerclimates.Flourandfeedreadilypickupmoisturefromtheair,muchmoreeasily than grain, and thus provide an excellentsubstrateformoulds.Flourwillgomouldymuchmore quickly than grain so it is imperative thatflourisnotstoredtoolong,unlessitispackagedinanon-porouscontainer,suchasaplasticbinorinpolythenelinedsacks.However,flourmusthave a water activity below 0.7 so that it doesnot release water to condense on the inside ofthecontainer. It isgenerally recommended thatflour or feed are stored for no longer than twoweeks in moderately hot and humid conditionsand even shorter where the relative humidityexceeds80%.

Themostcommonwaytopreventmouldistodry grain down to a ‘safe’ moisture content. At27°C, the lower limit of water activity that willpermitmouldgrowthis0.7.Thisisequivalenttoanequilibriumrelativehumidityintheairof70%.For cereal grains this is a moisture content of13-14%,forpulses11-13%andforoilseedssuchasgroundnuts7%.Ifgrainisfoundtobewetatthepointofpurchaseitisusuallyrejected.Ifthegrain takes up moisture during storage then itmustbedriedartificiallybythestoreowner.

However,mouldgrowthcanalsobepreventedby reducing the temperature of the grain. Thiscanbeachievedduringstoragebyventilatingthestock,eitherusingnaturalaerationorbyforcingairthroughthecommodityusingafan.Althoughthis can be achieved in temperate climates–maizecanbestoredforayearat15%moistureat15°C– it isnotsoeasilyachieved in tropicalcountries; at 15% and 30°C maize would onlylast three months. A system for aerating a bagstackisillustratedinFigure26.Dryingdependson the moisture content of the air in the storeas the system is dependent on aeration alone,there is no artificial drying. Drying bags is dif-

Pest management

30

ficultbecausetheairtendsnottopassthroughtheintergranularspacesbutratherbetweenthesacks, the lineof leastairflowresistance.How-ever,thesystemisconvenientbecausethegraincan remain in sacks. For artificial drying grainmustbeunloadedfromsacks,placedinthedryerand thenputback intosacksafterdrying.Evengrainstoredinbulkmustbeshiftedtoadryer.

There are many types of artificial dryer eachdesignedfordifferentthroughputrates.Adetaileddescriptionofallthetypesisbeyondthescopeofthisbookletbutasummaryofthemaintypesisgivenbelow.

Traydryers:Traydryers,sometimescalledflatbeddryersarethesimplestofthebatchdryers.Grainisloadedontomeshtrayswithinthedryertoadepthof600to700mmandwarm,dryairisblownthroughthetraysuntilthegrainhasbeendriedsufficiently.

Radial dryers: The basic design of the radialdrying bin consists of two vertical metal meshcylinders,oneinsidetheother(Figure27).Grainis loaded into thespacebetween the twocylin-dersandairisblownintotheinnercylinder,fromthere, it passes through the mesh wall and thebedofgrain,andoutoftheoutermeshwall.Aircanbesuckedoutofthecentralcylinder,revers-ingtheair flowthroughthegrain.Thesedryersarepopular,butthereisariskthatgrainnearesttotheinnercylindercanbeover-driedasthisis

where hot, dry air first makes contact with thegrain. Grain towards the outside, where the airleaving the grain, is cooler and wetter. Trans-portabledryerscanberentedoutforoccasionaluse;thismakesdryingaffordableforevensmall-scalefarmerswhodonothavesufficientcapitaltopurchaseadryeroftheirown.

Continuous flow dryers: These are designedto remove moisture from the grain rapidly byblowingorsuckinghotair through thegrainasitpassesthroughthesystemfromtoptobottom.The simpler designs of continuous flow dryershaveaholdingbinontopofthetalldryingsec-tion.Afinalcoolingsection,whereairatambienttemperatureisblownthroughthegrainisusuallyincorporated at the base of the dryer to avoidconveying hot grain into the rest of the system.The bed of grain may be vertical, horizontal orinclined.Grainmaybemovedbyvibration,scrap-ers,conveyors,orbygravity.Thedegreeofdryingis determined by the rate of grain flow throughthe dryer, and is usually controlled by varyingthespeedofoutlet conveyorsor thesizeof theoutletitself.

Tower (mixed-flow) dryers: These dryersresembletallrectangularstoragebins,fittedwitha largenumberofhorizontal, triangularshapedducts across the width of the dryer. Approxi-mately half of these ducts introduce warm, dryair into the grain whilst the others remove thecooled, damp air. Grain is fed in at the top andpassesdown,around theducts,bygravity.Withthe dryer full of grain, the grain moves slowlydownthroughthedryer,firstthroughthedryingsection and then a final cooling section usingambientair.

Louvered-bed dryer: This dryer is similar indesign to the tray batch dryer except that thegrain is dried as it passes over louvered-bedsthrough which heated air is blown rather thanbeing dried in situ. The depth and speed of themoving bed of grain is controlled to determinethedegreeofdrying.Therearetwobasicdesigns,thecascadedryerandconveyordryer.

FIGure 26 ventilation of conventional bag stack

Fan Po lyth en e sh eeting

D unn ag e

B A G ST A C K

Pallets to im p ro ve airflowacross th e top of th e stack


31

FIGure 27 Operating principle of simple radial drying bins

Central air tube

Expandedmetal wall

Airswept floor

Grain outlet

Air doors Air duct

Walded mesh andhessian wall

Extraction fan

PVC sleeve

The cascade dryer is a gravity fed cross-flowdryerwithgraindepthcontrolledbyaseriesofroller dams along the length of the louvered-bed. The degree of drying is controlled by thespeedoftheoutputelevator.Toavoidexcessivelylong lengths, larger dryers may involve severalchangesindirectionofgrainflow.

Inconveyordryersgrain isalsosupportedonan inclined louvered-bed through which air is

Pest management

blown, but grain flow through the dryer is by avariablespeed,heavyduty,rollerchainconveyor.These dryers may be single-directional, two-directionalormulti-directional.Thechanges indirection of grain flow mixes the grain, allowssome of the dried waste material to be blownfrom the grain and reduces the overall size ofthemachine.

FIGure 28 Operating principle of a single direction cascade dryer

Wet grain inlet

Roller dams

Moist air outlet

Dry grain outlet

Variable speed elevator

Cooling fanHot air

Fan and furnace

Coll air

33

hyGIene AnD stOre MAnAGeMent• Cleanallareaswherestockmaybekept in

stores, mills, around machinery; sweep atleastonceaweek;

• Remove from store and dispose of sweep-ingsandotherrubbish;

• Remove from store all empty sacks andpesticides where other space is available;otherwise keep non-food items separatedfromgrainandotherfoodstock;

• Keep store well maintained and in goodrepair; repair cracks and crevices, makegood where the floor has broken up, fill inholesinstructure;makesureventilatorscanbeopenandclosed;

• Fitwiremeshtoopeningstostoprodentandbird entry; fill in holes in doors, floor andwalls;

• Spray the fabric of the building, freightcontainer or truck with contact insecticidesolutiontokilloff insectpestsintheemptystore;

• Makesurethatanysacksthatarereusedarefreeofpests.

stOCK MAnAGeMent• Build stacks using an appropriate stacking

pattern so that they are stable but easy todismantle;

• Leaveagapof1mbetweenstacks,fromthewalls and beneath the roof eaves; ensurethatitispossibletogainaccesseasilytoallexposedsurfaces,includingthetop;

• Build the stack on dunnage of pallets orpoles, or on a polythene sheet if floor islevel;

• Inspectthestockandthestoreitselfatleastonceaweek;checkforthepresenceofpestsandtoconfirmtheeffectivenessofpestcon-trolproceduresthathadbeencarriedout;

• Use cards attached to stacks to record thehistoryandperformanceof thecommodity;userecordcards/sheetstorecordpestcon-trolproceduresandinspections

trAnsPOrt• Make sure truck or cart is clean and well

swept;• Spraythefabricofthetransportwithcontact

insecticide;• Ensurethatallpaperworkrelatedtotheload

isinorder;• Donotusehookstoloadandunloadsacks,

ratherusemanhandlingoraconveyor;• Donotoverload;• Iftransportcanbemadeairtight,fumigateif

pestsarepresent.

Pest MAnAGeMent• Fumigation should only be undertaken by

trainedpersonnel;• Onlyfumigateinairtightenclosuresorwhere

itcanbemadeairtight;• Fumigation should last at least 7 days,

beforeaerationbegins;• Aeratethoroughly;• Dispose of spent fumigation tablets by tip-

pingresidueinwater;• Spray store with contact insecticide to kill

off insects present before fumigation takesplace; do not use insecticides to provideresidualprotection;

• Only trained personnel should handle andapplycontactinsecticides;

• Neverworkalone;• Ensureasupplyofcleanwateristohand;• Wash off spillages from the body or from

othersurfacesimmediately;

summary of actions needed

34

• Accidents should be immediately reportedand details of the chemicals used shouldalwaysbemadeknowntothedoctor;

• Wash equipment thoroughly after each useoratheendofeachday;

• Useacleanchangeofclotheseachday.• Always have warning notices posted for

fumigationandpestcontroltakingplace.

• take care when handling synthetic rodenti-cides;ensurebaitisplacedappropriately;

• Makesurestockisdryatintake;useappro-priatedrierifitgainsmoistureduringperiodinstore;

• Ensurethatallnon-essentialpeoplearenotallowedaccesstothestore.


35

AppendixCalculation for the application of contact insecticide to store walls

Therearethreesteps:• Calculatetheareatobetreated• Calculatetheamountofinsecticidesolution

needed• Calculate the amount of diluted solution

neededThe store is empty. The area to be treated

will be theareaof fourwallsand the floor (theroofwillnotbesprayed,thereisnoceiling).Thedimensions of the two short walls are 5 x 5 m.and of the two long walls 20 x 5 m. The floordimensionsare20x5m.

The totalsurfaceareaofeachshortwall is5x5=25m2.

The total area of both short walls is 25 x 2 =50m2.

Thetotalsurfaceareaofeachlongwall is20x5=100m2.

The totalareaofboth longwalls is100x2=200m2.

Thesurfaceareaofthefloortobetreatedis20x5=100m2.

Therefore,thetotalsurfaceareaofthestoretobetreatedis:50+200+100=350m2.

The insecticide to be used is 20% Actellicemulsifiable concentrate (e.c.) volume/volume(v/v). This solution therefore contains 20 ml ofactiveingredient(a.i.)per100mlofsolution.

Wewanttoapplythechemicalatarateof1.0ga.i./10m2ofsurface.Asweneedtotreatatotalof350m2,wewillneed:350/10*1mlofa.i.=35mla.i.

However,theinsecticideisonly20%.Therefore100mlcontainsonly20gofa.i. 1ga.i. iscon-tainedin1/20*100ml=5ml.

Therefore35mla.i. iscontained in35/1*5=175mlof20%Actellic.

Thus we will use 175 ml of the insecticide ina water based solution. This solution has to beappliedatarateof5l/100m2.Totreat350m2wewillneed:350/100*5l=17.5l.

Therefore to spray the store fabric we willtake175mlof20%Actellicanddiluteitwithjustunder18lofwater(itisimpracticaltotrytomea-sureoutthewatermoreaccurately).

If thestorehad threebagstacks inplacewewouldneedtocalculatethefloorspaceoccupiedbythestacksandsubtractitfromthetotalstoreareabeforecalculatingtheamountofinsecticideneeded. This is because we cannot spray theflooroccupiedbythestacks.

If the threestackswereofequaldimensions:3x4m,theneachwouldoccupy12m2,andthetotaloccupiedbythethreewouldthenbe:3x12=36m2.

Asthetotalfloorareais100m2(fromabove),the actual floor area we can spray will only be:100–36m2=64m2.Thenthetotalsurfacetobetreatedwillbe:

50+200+64m2=314m2.Wewanttoapplythechemicalatarateof1.0

ga.i./10m2ofsurface.Asweneedtotreatatotalof 314 m2, we will need: 314/10 * 1 ml of a.i. =31.4mla.i.

However,theinsecticideisonly20%.Therefore100mlcontainsonly20gofa.i.

1ga.i.iscontainedin1/20*100ml=5ml.Therefore31.4mla.i.iscontainedin31.4/1*5

=157mlof20%Actellic.Ifwedonothaveanaccuratemeasureforthe

Actellic,wecanmeasureout160ml.Wewillalsoneedlessofthedilutedsolution:

314/100*5l=15.7lor,lessprecisely,16l.





training manual

2GOOD PRACTICES FOR ANIMAL FEED AND LIVESTOCK

The food produced by the farmer has a long journey to travel on its way to the consumer’s plate or the animal’s feed trough. There may be a long chain through which the crop will be transported, stored and processed, with accompanying losses in quality, quantity, nutrient content and monetary value. These losses can be substantial, and if they are allowed to occur and build up, will result in a significant loss in revenue for the farmer and the end user.

This booklet describes the causes of these potential losses and illustrates actions that should be undertaken to prevent or remedy them. It assumes that grain and grain products, including flour and animal feed, have reached the first point in the marketing chain after leaving the farm. The situation of transit storage and long-term storage is considered, and millers, traders and feed compounders are also included.

The booklet is not intended to be used solely by the ultimate beneficiaries themselves, though it may well be. It is intended to be used by anyone who is involved in providing practical advice to counteract the causes of deterioration of grain and grain products along the marketing chain. These may be pest control suppliers, retailers and wholesalers, extension personnel within and outside of government, staff of trading organisations including marketing boards, and trade unions.

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MAINTAINING QUALITY OF FOOD AND FEED GRAIN THROUGH … · 2012-11-30 · MAINTAINING QUALITY OF FOOD AND FEED GRAIN THROUGH TRADE AND PROCESSING training manual GOOD PRACTICES FOR