Maize: the gift of the gods

The participants of the symposium at a glance.synthetic capacity by controllingthe fungus.Bernd Rodemann, a plantpathologist at the GermanFederal Biological ResearchCentre for Agriculture andForestry, discussed – like manyother speakers – how variousfactors have a significantimpact on infection: climaticconditions at the time of flowering;preceding crop; soil cultivation;and finally, choice ofcrop variety [see Courier 2/04]– with particular reference totest results from new varieties.Rodemann also showed data onthe relationship between varietalplant height and susceptibilityto Fusarium: taller varietiesare usually less susceptible,because spores have furtherto travel when they arespread from the ground toflowering parts by rain-splashand wind. Taken together, thisknowledge can be translatedinto practical recommendationsfor farmers. Finally, Rodemannhinted how harvesting and storageof cereals should be donesuch that the mycotoxin contentcan be kept as low as possible,or indeed to reduce theformation of mycotoxins. Thefarmer should avoid harvestingduring a period of high relativeair humidity, and should ensurethat the crop is as dry as possibleat the time of harvest. Theharvested seed should becleaned or sieved, and driedbefore storage such that itsmoisture content is below 15%.Storage temperatures shouldnot exceed a maximum of 30°C.Another way of protectingagainst Fusarium is to usefungicides. Kemper had posedthe question: „I know that thebest time to apply a fungicide isone or two days after infection– but when is that exactly? If Iwant to catch the right moment,I’ll need a good forecastingsystem.“ Such „infection riskforecast models“ have indeedbeen developed. They aim topredict the risk of infection afarmer should expect for hiscrop, in order to help him totake the appropriate measuresin good time. Art Schaafsmafrom Canada, Marcia McMullenfrom the USA, Claude Maumenéfrom France and RicardoMoschini from Argentina eachpresented a different model,each with its own approach.For all of these models, themain emphasis is on the analysisof meteorological data, butagronomic field data such ascrop growth stage, varietal susceptibility,previous crop, andthe soil cultivation methodused are also taken into consideration.Some forecasting servicesprovide the farmer withconcrete recommendations asto the best timing for applyingfungicides.Just as important as the timingof spraying is the technologyused to make the application.Reinhard Frießleben, Headof Application Technology atBayer CropScience, describedcurrent trends and new knowledgeregarding the best applicationtechnologies; the mainemphasis of his presentationwas on choosing the best typeof nozzle, the most importantcomponent of the sprayingequipment. How much of thesprayed product actually reachesthe target, where it can beeffective? The degree of coverageachieved is strongly dependenton the type of nozzle used.The effectiveness of the applicationis determined by dropletsize and distribution. Thesmaller the droplet, the better itsticks to the plant surface, andthe longer and more effectivelythe product can work. Unfortunatelythough, smallernozzles have the disadvantageof being more problematic anddifficult to use in practice.Drift-reducing nozzles are onlyto be recommended for sensitivefield-edges, according toFrießleben. The amount ofwater used is another significantdeterminant of the successof a spray application. Studieshave shown that 200 l/ ha is theoptimum amount. However,Frießleben again stressed theprime importance of spray timing.Even if the timing of applicationand coverage of cropsurfaces are optimal, fungicidesdiffer significantly in theirefficacy against Fusarium. AkosMesterházy of the HungarianSzeged University presentedthe results of trials in which hehad tested the potential of variousfungicides. He showed thatonly a few products providedconsistent protection across seasons– here, Bayer CropScience’sprothioconazole was the bestperformer.At the end of the Symposium,Friedrich Kerz-Möhlendick,Team Leader of theCereal Fungicides group atBayer CropScience describedfor the participants what BayerCropScience has to offer forcontrolling Fusarium. He showedthat the combination of theactive substances tebuconazoleand prothioconazole in theproduct Prosaro ® gave the mostcomprehensive protectionagainst Fusarium. Respondingto Kemper’s call for help, Kerz-Möhlendick ended his contributionby extending BayerCropScience company slogan:„We’re not only your partnerfor growth – we’re also yourpartner for Fusarium control.“Please pay a visit to ourwebsites, where you will findfurther information relating to„Fusarium“.Here are the addresses:www.bayercropscience.comand www.agrocourier.com. ■16 CORREO 1/05