二油菜霜霉病綠色防控

II

GreenPreventionandControlofRapeDownyMildew

油菜霜霉病我國各油菜區重要病害，長江流域、東南沿海受害重。一般發病率為10%～30%，嚴重時達80%以上。

Rapedownymildew:ItisanimportantdiseaseinvariousraperegionsinChina,whichseriouslyharmstheYangtzeRiverBasinandthesoutheastcoast.Thegeneralincidencerateis10%~30%,andreachesabove80%inseverecases.（一）癥狀識別

油菜各生育期均可感病，為害油菜地上部分各器官。

葉片：發病后，初為淡黃色斑點，后擴大成黃褐色大斑，受葉脈限制呈不規則形，葉背面病斑上出現霜狀霉層。二油菜霜霉病綠色防控II

GreenPreventionandControlofRapeDownyMildew

(I)SymptomIdentification

Rapeissusceptibletothediseaseatallgrowthstages,causingharmtothe

abovegroundorgansofrape.

Leaves:Aftertheonsetofthedisease,lightyellowspotsappearatfirst,andthenexpandintolargeyellowish-brownspots,whichareirregularlyshapedduetothelimitationofleafveins.Adownymoldlayerappearsonthespotsonthebackoftheleaves.油菜霜霉病病葉正面癥狀油菜霜霉病病葉背面癥狀SymptomsontheFrontofDownyMildewDiseasedLeavesofRapeSymptomsontheBackofDownyMildewDiseasedLeavesofRape

莖、薹、分枝和花梗：感病后，初生褪綠斑點，后擴大成黃褐色不規則形斑塊，斑上有霜霉病菌。花梗發病后有時肥腫、畸形，花器變綠、腫大，呈“龍頭”狀，表面光滑，上有霜狀霉層。嚴重時全株發病，布滿霜霉，變褐枯死。

Stems,stalks,branches,andpedicels:Afterinfectedwiththedisease,chloroticspotsappearfirst,andthenexpandintoyellowish-brownirregularpatcheswithdownymildewonthespots.Aftertheonsetofthepedicel,sometimesitisswollenanddeformed,andthefloralorgansturngreenandswollen,showinga"dragonhead"shapewithasmoothsurfaceandafrostymoldlayer.Inseverecases,thewholeplantbecomesdiseased,andiscoveredwithdownymildew,andturnsbrownandwitherstodeath.（二）病原寄生霜霉，屬鞭毛菌亞門真菌油菜霜霉病病菌孢囊梗及孢子囊2.孢子囊

3.孢子囊的萌發4.卵孢子

(II)EtiologyParasiticdownymildew,belongingtoflagellariasubphylumfungi

DownymildewpathogenofrapeSporangiophoresandsporangia2.Sporangia3.Germinationofsporangia4.Oospores（三）發病規律越夏：冬油菜區，病菌以卵孢子隨病殘體在土壤中、糞肥里和種子內越夏，秋季萌發后侵染幼苗，病斑上產生孢子囊進行再侵染。越冬：冬季病害擴展不快，并以菌絲在病葉中越冬，翌春氣溫升高，又產生孢子囊借風雨傳播再次侵染葉、莖及角果，油菜進入成熟期，病部又產生卵孢子，可多次再侵染。遠距離傳播主要靠混在種子中的卵孢子。至于近距離傳播，除混在種子、糞肥中的卵孢子直接傳到病田外，主要靠氣流和灌溉水或雨水傳播。

(III)OccurrenceRegularityOversummer:Inwinterraperegions,thepathogensoversummerasoosporesinthesoil,manure,andseedswiththediseasedresidues.Aftergerminationinautumn,theyinfecttheseedlings,andsporangiaareproducedonthespotsforsecondaryinfection.Overwinter:Inwinter,thediseasedoesnotexpandrapidlyandoverwintersinthediseasedleavesashyphae.Inthefollowingspring,theairtemperaturerises,andsporangiaareproducedtospreadbywindandraintoinfectleaves,stemsandcornerfruitsagain.Whenrapeentersthematuritystage,thediseasedpartsproduceoosporesagaintocauserepeatedre-infection.Long-rangespreadmainlydependsonoosporesmixedinseeds.Asforclosespread,oosporesmixedinseedsandmanurearemainlytransmittedbyairflowandirrigationwaterorrainwater,exceptthattheyaredirectlytransmittedtodiseasedfieldsthroughseedsandmanure.（三）發病規律該病發生與氣候、品種和栽培條件關系密切氣溫8～16℃、相對濕度高于90%、弱光利于該菌侵染。長江流域油菜區冬季氣溫低，雨水少發病輕，春季氣溫上升，雨水多，田間濕度大易發病或引致薹花期該病流行。連作地、播種早、偏施過施氮肥或缺鉀地塊及密度大、田間濕氣滯留地塊易發病。

(III)OccurrenceRegularityTheoccurrenceofthediseaseiscloselyrelatedtoclimate,cultivarandcultivationconditionsItisconducivetothebacterialinfectionwhenthetemperatureis8~16°C,therelativehumidityisabove90%,andthelightisweak.IntherapeareaoftheYangtzeRiverBasin,theairtemperatureislowinwinter,withlessrain,andthediseaseisgentle;inspring,theairtemperaturerises,withmorerainandhighfieldhumidity,itiseasytocausethediseaseorcausethediseasetospreadduringtheboltingandfloweringperiod.Continuouscropping,earlysowing,excessiveapplicationofnitrogenfertilizerorpotassium-deficientplotsandplotswithhighdensityandmoistureretentioninthefieldarepronetothedisease.（四）防治技術

1、因地制宜種植抗病品種。如中雙4號、兩優586、新油9號、蓉油3號等。提倡種植甘藍型油菜或浠水白等抗病的白菜型油菜。2、與禾本科作物輪作l～2年，或水旱輪作，可大大減少土壤中卵孢子數量，降低菌源。3、種子消毒播種前用25％甲霜靈可濕性粉劑按干種重量0.3％拌種。也可用50％福美雙或75％百菌清可濕性粉劑拌種，藥量為種量的0.4％。

(IV)ControlTechnique1.Plantdisease-resistantvarietiesaccordingtolocalconditions.SuchasZhongshuangNo.4,LiangyouNo.586,XinyouNo.9andRongyouNo.3.ItissuggestedtoplantBrassicanapusorXishuibaiandotherdisease-resistantcabbagerapes.2.Rotationwithpoaceouscropsfor1~2yearsorpaddy-uplandrotationcangreatlyreducethenumberofoosporesinthesoilandreducethepathogensource.3.Seeddisinfection:Beforesowing,mixtheseedswith25%metalaxylwettablepowderby0.3%ofthedryseedweight.Theseedscanalsobemixedwith50%thiramor75%chlorothalonilwettablepowder,andthedosageis0.4%oftheseedweight.

4、加強田間管理，做到適期播種，不宜過早。根據土壤肥沃程度和品種特性，確定合理密度。采用配方施肥技術，合理施用氮磷鉀肥提高抗病力。雨后及時排水，防止濕氣滯留和淹苗。發現病葉隨時摘除，收獲后搞好田園衛生。5、藥劑防治，一般在3月上旬抽薹期，調查病情發生情況，當病株率達20%以上時，用烯酰嗎啉、甲霜·錳鋅、霜霉威鹽酸鹽、代森聯等，一般隔7～10d噴1次，視病情防治2～3次。4.Strengthenfieldmanagementandsowseedsinduetime,whichshouldnotbetooearly.Determinethereasonabledensityaccordingtothesoilfertilityandvarietycharacteristics.AdoptformulafertilizationtechnologyandreasonablyapplyNPKfertilizertoimprovediseaseresistance.Drainwaterintimeafterraintopreventmoistureretentionandseedlingflooding.Removethediseasedleavesatanytime,andensurefieldhygieneafterharvest.5.Chemicalcontrol.Generall