《植物病蟲害綠色防控技術(shù)》課件-三、玉米紋枯病綠色防控（雙語版）

玉米紋枯病綠色防控

GreenPreventionandControlofCornSheathBlight

玉米紋枯病又稱玉米爛腳瘟，我國始見于1966年的吉林省，在上世紀(jì)70年代中后期逐漸成為我國玉米主產(chǎn)區(qū)的一種重要病害。在四川、重慶、貴州、江蘇、浙江、河南、陜西、山東等省及兩湖、兩廣地區(qū)的春、夏、秋玉米均有紋枯病的發(fā)生。一般年份發(fā)病率達(dá)40%，嚴(yán)重時發(fā)病率達(dá)70%。

Cornsheathblight,alsoknownascornrotblight,wasfirstseeninJilinProvincein1966andgraduallybecameoneofthemajordiseasesinthemaincorn-productionareasinChinainthemiddleandlate1970s.SheathblightoccursinSichuan,Chongqing,Guizhou,Jiangsu,Zhejiang,Henan,Shaanxi,Shandongandotherprovinces,aswellasinspring,summerandautumninHunan,Hubei,GuangdongandGuangxi.Theincidenceincommonyearsis40%,or70%inseriouscases.三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight（一）癥狀識別

SymptomIdentification

玉米紋枯病從苗期至穗期均可發(fā)生，危害高峰期在玉米子粒形成至灌漿充實期。該病主要危害葉鞘、葉片和穗部，也侵害莖稈。最初多由近地面的葉鞘發(fā)病，由下而上逐步發(fā)展。

Cornsheathblightcanoccurfromtheseedlingstagetotheheadingstage,andthepeakharmperiodisfromtheformationofcornkernelstothefillingstage.Thediseasemainlyharmsleafsheaths,leavesandears,andalsoharmsstems.Atfirst,thediseasemostlyoccursfromtheleafsheathneartheground,

andgraduallydevelopsfrombottomtotop.其癥狀為在葉片和葉鞘上形成典型的呈暗綠色水浸狀的同心斑，大面積覆蓋被侵染葉片和苞葉，形成不規(guī)則的云紋狀病斑，中部灰褐色，邊緣深褐色，隨后病斑逐漸擴大，包圍整個葉鞘直至葉鞘葉片干枯；病斑向上擴展至果穗基部，果穗停止發(fā)育并迅速發(fā)展至全穗，最后死亡。

Thesymptomsincludethattypicaldarkgreenwater-soakedconcentricspotsareformedontheleavesandleafsheaths,coveringtheinfectedleavesandbractsinalargeareatoformirregularmoire-likespots,withgrayishbrowninthemiddleanddarkbrownontheedges,andthenthespotsgraduallyexpandandsurroundthewholeleafsheathuntiltheleavesoftheleafsheathswither.Spotsspreadupwardtothebaseoftheears,whichstopdevelopingandrapidlydeveloptothewholeears,andfinally,theearsdie.三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight三玉米紋枯病綠色防控

III.GreenPreventionandControlofCornSheathBlight環(huán)境潮濕時，病斑上可看見稀疏的白色蛛絲狀菌絲體。病組織內(nèi)或葉鞘與莖稈之間常產(chǎn)生褐色顆粒狀菌核，菌核周圍有少量菌絲和寄主相連。成熟的菌核灰褐色，大小不等，形狀各異，多為扁圓形，極易脫離寄主，遺落田間。Whentheenvironmentiswet,sparsewhitearachnoidmyceliumcanbeseenonthespots.Browngranularsclerotiaareoftenproducedindiseasedtissuesorbetweenleafsheathsandstems,andasmallamountofhyphaeareconnectedtothehostaroundthesclerotia.Maturesclerotiaaregrayishbrown,indifferentsizesandshapes,mostlyoblate.Theymayeasilydetachfromthehostandbeleftinthefield.三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight（二）病原

多數(shù)研究者認(rèn)為，玉米紋枯病的病原菌主要由半知菌亞門的立枯絲核菌、禾谷絲核菌和玉蜀黍絲核菌3個種，其中玉蜀黍絲核菌常危害果穗導(dǎo)致穗腐，禾谷絲核菌主要侵害小麥，而玉米紋枯病的主要病原菌是立枯絲核菌。

Mostresearchersbelievethatthepathogensofcornsheathblightmainlyconsistofthreespecies:Rhizoctoniasolaniofdeuteromycotina,RhizochondriacerealisandRhizoctoniazeaeVoorhees.RhizoctoniazeaeVoorheesoftenharmsfruitearsandcausesearrot.Rhizochondriacerealismainlyharmswheat,whilethemainpathogenofcornsheathblightisRhizoctoniasolani.玉米紋枯病菌絲幼嫩時無色，較細(xì)，分枝呈直角、近直角或銳角，分枝處大多有縊縮現(xiàn)象，離分枝不遠(yuǎn)處有隔膜。菌絲細(xì)胞多核，一般3～10個，多數(shù)4～6個。隨菌齡和分枝增加，新分枝細(xì)胞漸變粗短，達(dá)一定程度后糾結(jié)成菌核。菌核初為白色，后變?yōu)椴煌潭群稚贤沟装蓟蚱?，球形或橢圓形，表面粗糙，單生或多個結(jié)成不規(guī)則形，表面有許多微孔。

Thehyphaeofcornsheathblightarecolorlessandthinwhenyoung,withbranchesatright,nearlyright,oracuteangles.Mostofthebranchesareconstricted,andthereisaseptumnotfarfromthebranches.Hyphaearemultinucleated,generally3~10,mostly4~6.Withtheincreaseoffungusinstarandbranches,thenewlybranchedcellsgraduallybecomethickerandshorter,andthenbecomesclerotiaafterreachingacertaindegree.Thesclerotiaarewhiteatfirst,thenbrownofvaryingdegrees,concaveorflatontheupperpart,sphericaloroval,roughonthesurface,solitaryorirregularinshape,withmanymicroporesonthesurface.三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight（三）發(fā)生規(guī)律

OccurrenceRegularity

初侵染源為玉米田土表和淺土層中的越冬菌核。在溫濕度、光照條件適宜時，越冬菌核開始萌發(fā)菌絲，侵染玉米植株基部葉鞘，通過病、健葉片和葉鞘相互搭接等可造成再侵染，使病害逐步向上蔓延擴展引發(fā)玉米紋枯病。Theprimaryinfectionsourceisoverwinteringsclerotiaonthesurfaceofcornfieldsandintheshallowsoillayer.Whenthetemperature,humidity,andlightconditionsaresuitable,theoverwinteringsclerotiabegintogerminatehyphaeandinfecttheleafsheathsatthebaseofcornplants.Reinfectioncanbecausedbyoverlappingthediseasedandhealthyleaves,andleafsheaths,sothatthediseasegraduallyspreadsupwardandexpands,causingcornsheathblight.病菌可通過表皮、氣孔和自然孔口3種途徑侵入寄主，其中以表皮直接侵入為主。多雨潮濕時病部長出稠密的白色菌絲體，之后菌絲密集成多個菌核，最初為白色，后變?yōu)楹稚?，最后呈暗褐色。成熟的菌核多為圓形或扁圓形，易脫離寄主，遺落田間成為再次侵染的菌源。玉米種子和病株殘體可帶菌，但不能引起玉米植株發(fā)病。

Pathogenicbacteriacaninvadethehostinthreeways:epidermis,stomataandnaturalstomata,ofwhichthedirectinvasionofepidermisisthemainway.Whenitisrainyandwet,densewhitemyceliumwillgrowattheaffectedpart,andthenthehyphaearedenselyintegratedwithmultiplesclerotia,initiallywhite,thenbrown,andfinallydarkbrown.Thematuresclerotiaaremostlyroundoroblate,whichareeasytodetachfromthehostandbecomethesourceofsecondaryinfectioninthefield.Cornseedsanddiseasedplantresiduesmaycarrybacteria,buttheycannotcausecornplantdiseases.

三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight玉米紋枯病病菌屬高溫高速型菌群，病菌發(fā)育適溫為28～32℃，在30℃和有足夠的濕度時2d就形成新的菌核。連續(xù)陰雨或天氣濕悶有利發(fā)病。過分密植，施氮過多，植地連作或前作地為水稻紋枯病嚴(yán)重的田塊本病往往發(fā)生嚴(yán)重。三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight三玉米紋枯病綠色防控

III.GreenPreventionandControlofCornSheathBlightCornsheathblightpathogenicbacteriaisahigh-temperatureandhigh-speedflora.Theoptimumtemperatureforpathogendevelopmentis28–32°C,andnewsclerotiawillbeformedin2daysat30°Cwithsufficienthumidity.Continuousrainorwetandstuffyweatherisconducivetotheonsetofthedisease.Excessivelydenseplantingandexcessivenitrogenapplicationoftenleadtoseriousdiseaseinfieldswithcontinuouscroppingorpre-croppingricesheathblight.（四）防治技術(shù)

ControlTechnique

1、控制菌源玉米收獲后，及時深耕滅茬，清除病原及時深翻消除病殘體及菌核，集中燒毀或高溫堆肥，盡量減少侵染來源；發(fā)病初期摘除病葉，并用藥劑涂抹葉鞘等發(fā)病部位。1.Controlbacterialsource:Afterthecornisharvested,deepplowingandstubbleremovalshouldbecarriedoutintime,pathogensshouldberemoved,diseasedresiduesandsclerotiashouldbeeliminatedintime,andcentralizedburningorhigh-temperaturecompostingshouldbeadoptedtominimizeinfectionsource;attheearlystageofthedisease,thediseasedleavesshouldberemovedandthediseasedpartssuchasleafsheathsshouldbeappliedwithchemicals.

2、選用抗、耐病品種目前生產(chǎn)上尚無對玉米紋枯病免疫的品種，高抗紋枯病的品種也較少，但是選用早熟、耐病、高產(chǎn)的玉米良種，同樣條件可降低病情20%～30%。2.Selectdisease-resistantcultivars.Atpresent,therearenocultivarsimmunetocornsheathblightinproduction,andtherearefewcultivarswithhighresistancetosheathblight.However,selectingearly-maturing,disease-resistantandhigh-yieldingcorncultivarscanreducethediseaseby20%~30%underthesameconditions.三玉米紋枯病綠色防控III.GreenPreventionandControlofCornSheathBlight

3、加強栽培管理實行輪作，合理密植，及時排除田間積水，降低田間濕度，消滅田間雜草。合理施肥，避免氮肥施用過多，以控制病害發(fā)生。

3.Strengthencultivationmanagement:Croprotationshouldbecarriedout,plantingshoul