水稻惡苗病從苗期至抽穗期均可發生
，一般有3個較明顯的發病高峰期。在播種後15tianzuoyouchuxiandiyigefabinggaofeng，zaishuidaofenniegaofengqichuxiandiergefabinggaofeng，zaishuidaoyunsuiqichuxiandisangefabinggaofeng。zaiqianlianggegaofengqifabingjiaoyanzhong。daijunzhongzishishuidaoemiaobingdezhuyaochuanranyuan
，qicishibingdaocao。emiaobingbingjunyifenshengbaozifuzhezaizhongzibiaomianhuoyijunsitiqianfuzaizhongzineiyuedong。bozhongbingguhuoyongbingdaocaofugaicuiya，junkeyinqiyoumiaofabing。miaoqifabing，bingmiaobijianmiaoxigao
，yepian、葉ye鞘qiao細xi長chang，葉ye色se淡dan黃huang
，根gen係xi發fa育yu不bu良liang，部bu分fen病bing苗miao在zai移yi栽zai前qian後hou不bu久jiu死si亡wang。病bing死si植zhi株zhu表biao麵mian產chan生sheng分fen生sheng孢bao子zi，能neng經jing風feng雨yu傳chuan播bo到dao健jian苗miao
，從cong傷shang口kou侵qin入ru
，造zao成cheng多duo次ci再zai侵qin染ran。但dan這zhe種zhong再zai侵qin染ran能neng力li比bi較jiao弱ruo，在zai田tian間jian侵qin染ran健jian康kang稻dao苗miao的de可ke能neng性xing很hen小xiao。

       播前用藥浸種是防治惡苗病的有效措施，適用藥有氰烯菌酯、咯菌腈、乙蒜素、咪(mi)鮮(xian)胺(an)等(deng)。但(dan)用(yong)藥(yao)量(liang)過(guo)低(di)或(huo)用(yong)藥(yao)濃(nong)度(du)過(guo)低(di)會(hui)導(dao)致(zhi)防(fang)效(xiao)下(xia)降(jiang)，造(zao)成(cheng)惡(e)苗(miao)病(bing)發(fa)生(sheng)。用(yong)藥(yao)浸(jin)種(zhong)時(shi)間(jian)過(guo)短(duan)
，也(ye)會(hui)導(dao)致(zhi)防(fang)效(xiao)下(xia)降(jiang)。部(bu)分(fen)地(di)區(qu)水(shui)稻(dao)惡(e)苗(miao)病(bing)病(bing)菌(jun)對(dui)咪(mi)鮮(xian)胺(an)產(chan)生(sheng)了(le)抗(kang)性(xing)，在(zai)這(zhe)些(xie)地(di)區(qu)，宜(yi)換(huan)用(yong)氰(qing)烯(xi)菌(jun)酯(zhi)、乙蒜素、咯菌腈等藥浸種。在水稻浸種過程中，病種子上的病菌會汙染無病種子。水稻惡苗病病菌主要在催芽期間侵染芽穀，此時稻種堆積、溫wen濕shi度du適shi宜yi，由you部bu分fen稻dao種zhong攜xie帶dai的de分fen生sheng孢bao子zi大da量liang萌meng發fa，不bu僅jin侵qin染ran原yuan來lai帶dai菌jun的de稻dao種zhong，還hai侵qin染ran原yuan來lai不bu帶dai菌jun的de稻dao種zhong
，使shi染ran病bing率lv大da幅fu度du提ti高gao。一yi般ban催cui芽ya的de比bi不bu催cui芽ya的de發fa病bing重zhong
，催cui芽ya時shi間jian越yue長chang發fa病bing越yue重zhong。用yong藥yao浸jin種zhong後hou不bu經jing催cui芽ya或huo催cui至zhi露lu白bai播bo種zhong能neng有you效xiao控kong製zhi惡e苗miao病bing發fa生sheng。有you研yan究jiu表biao明ming，縮suo短duan浸jin種zhong催cui芽ya的de時shi間jian


，對dui惡e苗miao病bing也ye有you顯xian著zhu的de預yu防fang作zuo用yong
，以yi幹gan種zhong直zhi接jie播bo種zhong最zui為wei明ming顯xian。相xiang對dui於yu浸jin種zhong催cui芽ya來lai說shuo，幹gan種zhong直zhi接jie播bo種zhong對dui惡e苗miao病bing的de病bing株zhu防fang效xiao可ke達da80％以上。

      上述移栽、機插稻田惡苗病發生較重，可能與浸種選藥不當、浸種質量差
、催(cui)芽(ya)時(shi)間(jian)長(chang)等(deng)有(you)較(jiao)大(da)關(guan)係(xi)。旱(han)直(zhi)播(bo)水(shui)稻(dao)，一(yi)般(ban)播(bo)種(zhong)幹(gan)籽(zi)
，不(bu)催(cui)芽(ya)
，病(bing)菌(jun)侵(qin)染(ran)率(lv)低(di)，即(ji)使(shi)有(you)部(bu)分(fen)帶(dai)菌(jun)種(zhong)子(zi)，病(bing)菌(jun)一(yi)般(ban)也(ye)不(bu)會(hui)侵(qin)染(ran)健(jian)苗(miao)
，因(yin)而(er)發(fa)病(bing)輕(qing)或(huo)不(bu)發(fa)病(bing)。