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1 霜霉病 主要发生在叶片上 ,也可在茎、花梗上发生。叶片上病斑 ,初呈水浸状黄绿至黄褐色斑点 ,后扩大成多角形或不规则形 ,叶背生白色霉状物 ,重时叶片枯黄 ,此病多发生在连雨、多雾、温度忽高忽低时。防治方法 :①选择抗病品种 ;②合理轮作 ,适期播种 ;③播前进行种子消毒
Downy mildew occurs mainly on the leaves, but can also occur on stems and pedicels. Leaf lesions on the spot was initially flooded yellow-green to brown spots, then expanded into polygons or irregular shape, leaf back white mildew, when the weight of yellow leaves, the disease occurred in even the rain, fog , When the temperature fluctuated suddenly. Prevention and treatment methods: ① select resistant varieties; ② reasonable rotation, sowing; ③ sowing before sowing