有些菜農對於各種蔬菜病害,不論是真菌性病害、細菌性病害、病毒性病害還是生理性病害,看見蔬菜葉、果稍有變化就噴施農藥;duiyugezhongshucaichonghai,buguanshiyoumanleiyinqidehaishiyachongyinqide,yebuguansuoyongzhiyaonengbunengjianzhiqichong,zhiyaojianchongjiudayaopensha。zhezhongzuofashibuduide。
其qi實shi,每mei種zhong病bing蟲chong都dou有you獨du特te的de習xi性xing與yu危wei害hai特te點dian,如ru白bai粉fen病bing易yi侵qin害hai瓜gua菜cai幼you嫩nen部bu分fen,黑hei斑ban病bing則ze易yi從cong下xia部bu葉ye片pian開kai始shi浸jin染ran,蟎man類lei多duo集ji結jie於yu葉ye片pian背bei麵mian吸xi取qu蔬shu菜cai汁zhi液ye。大da部bu分fen防fang治zhi病bing蟲chong害hai的de藥yao劑ji,專zhuan一yi性xing特te別bie強qiang,往wang往wang針zhen對dui某mou一yi種zhong或huo某mou一yi類lei病bing原yuan物wu引yin起qi的de病bing害hai或huo蟲chong害hai,對dui其qi他ta病bing害hai或huo蟲chong害hai則ze無wu效xiao。所suo以yi在zai施shi藥yao時shi一yi定ding要yao因yin病bing、因蟲施藥。
個(ge)別(bie)菜(cai)農(nong)見(jian)到(dao)棚(peng)室(shi)內(nei)有(you)蟲(chong)害(hai),就(jiu)想(xiang)徹(che)底(di)消(xiao)滅(mie)掉(diao),其(qi)實(shi)完(wan)全(quan)沒(mei)有(you)必(bi)要(yao)。從(cong)經(jing)濟(ji)學(xue)角(jiao)度(du)來(lai)講(jiang),棚(peng)室(shi)內(nei)的(de)害(hai)蟲(chong)隻(zhi)要(yao)不(bu)超(chao)過(guo)防(fang)治(zhi)指(zhi)標(biao)就(jiu)不(bu)應(ying)該(gai)防(fang)治(zhi),否(fou)則(ze)有(you)可(ke)能(neng)會(hui)降(jiang)低(di)產(chan)出(chu)投(tou)入(ru)比(bi),得(de)不(bu)償(chang)失(shi)。
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