鞭毛菌亚门真菌Mastigomycotina.ppt

白锈病白锈病白锈病（5）霜霉科PeronosporaceaeTheycause‘downymildew’diseasesofseveralimportantcrops.Thename‘downymildew’isgivenbecauseofthehangingsporangiophoresfromthelowersurfaceofleavesthroughstomata.Thesporangiaphoresbranchandbearsporangiaattheirtips.Thesporangiausuallybehaveasconidia.Thevariousgeneraareidentifiedonthebasisofthecharacteristicbranchingoftheirsporangiophores.TheimportantgeneraarePeronospora,Bremia,Basidiospora,Sclerospora,Plasmopara,Pseudoperonospora,Bremiella.1、指梗霉属Sclerospora孢囊梗主轴粗短，顶端不规则二叉分枝；藏卵器与卵孢子壁愈合。如谷子白发病感

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鱼丝囊菌属Aphanomyces丝囊菌引起萝卜根腐3、霜霉目Peronosporales无两游现象，游动孢子囊大多数为球形。卵孢子为单卵球。ThegenerabelongingtoPeronosporalesshowmorphologicalchangeswhicharemoresuitedtotheamphibiousorterrestrialhabitatofthesefungi.Sporangiaindryweatherinsteadofformingzoosporesgerminatedirectlybygermthbe,thusbehavingasconidia.Theintercellularhypheaofparasiticgeneraformhaustoriawhichenterhostcellsandabsorbnutrients.Pythiaceae,Peronophthoraceae,Albuginaceae,Peronosporaceae.（1）腐霉属Pythium：重要病原，主要引起腐烂如引起腐烂的瓜果腐霉和幼苗猝倒。主要存在于土壤中。P.debaryanum—Dampingoffoftobaccoandchillies.P.aphanidermatum—Softrotofpapaya,dampingoffofpotato.P.graminicolum—Rhizomeandrootrotofturmertic.P.myriotylum—‘Footrot’ofginger.瓜果腐霉图猝倒病原猝倒病图猝倒病图猝倒病图猝倒病图腐霉引起腐烂病害控制Control:DampingoffofseedlingsandrootrotscausedbyPythiumaremorecommoninsoilsofhighwaterandhumuscontent,Thus,waterlogginginfieldsshouldbeavoided.Soilsterilizationtokillthefungusisdonethroughfungicides.Butbettermethodofcontrolistotreattheseedsbeforesowingwithprotectivefungicides.（2）疫霉属PhytophthoraPhytophthorasurvivesinthedeadhosttissuesleftinthesoil.P.infestans,asarule,survivesasdormantmyceliumininfectedpotatotubers.However,itcanbeculturedinlaboratory番茄晚疫病辣椒疫病等