一、傷根黃葉
genxishoushangzaochengdehuangyeshidangqianhuangguahuangyedezuizhuyaoyuanyin,zhezhonghuangyezhuyaoshijiaoshuishifeibudangzaochengshanggen,huojiaoshuihouyudaolianyintianzaochengougensuozhi。jianyiyingcaiqupenguanjiehe,zonghefangzhi。pen,jiyemianpenshihanxinhehantiedeyemianfeifangzhiyepianshuailao,cujinyepianbianlv。guan,jiguanshishenggenzhuangmiaojihuojiakesudengcujingenxishengchang。
二、缺素黃葉
缺素型黃葉分為中、下部老葉先黃和中、上部嫩葉先黃兩種情況。中、下部老葉黃,所缺元素多為氮、鉀等;中、上部嫩葉先黃,所缺元素多為鈣、鐵、鋅等。建議應根據黃葉發病的不同部位、不同表現,選擇正確的葉肥進行噴施補充。如缺鉀可噴施磷酸二氫鉀500倍液,缺氮可噴施300倍的尿素液等。
三、病害黃葉
霜黴病、角斑病等病害是造成黃瓜黃葉的重要原因,霜黴病和角斑病多為害黃瓜的中下部葉片。霜黴病的主要症狀:yepianranbingshi,chuqiyeyuanheyebeimianchuxianshuizizhuangbingban,suihoubingbanzhujiankuoda,chengsanjiaoxingdanhuanghesehuohuanghesebankuai,shidugaoshi,yebeimianhuoyemianhuichangchuhuiheisemeiceng,yanzhongshizhizhuyipiankuhuang。jiaobanbingyushuangmeibingzhengzhuangdezhuyaoqubiezaiyu,jiaobanbingdebingbanyiposuichuankong,shidugaoshiyebeiyichurubaisehunzhuoshuimozhuangjunnong。duiyubinghaihuangye,yingjishishiyongshajunjijinxingfangzhi,yiban7~10天噴一次。霜黴病可用克露、安克、霜脲錳鋅等藥劑防治;角斑病可用加瑞農、可殺得、噻枯唑等藥劑。
四、藥害黃葉
菜農朋友在用藥防病時,用藥不當,也能導致葉片發黃。一般用藥量過大,如噴施代森錳鋅過量,容易出現錳中毒,造成葉片發黃、葉脈扭曲變形等。建議用藥務必合理,一旦發生藥害後可葉麵噴施愛多收6000倍液混加600倍液的雲大120加以緩解。
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