一、症状的识别 l、黄瓜苗猝倒病。幼苗近地茎基部一圈呈水溃状病斑,病部黄褐色,干缩;幼叶凋萎变色前幼苗就折倒死亡。当土壤在潮湿情况下,病部和病株周围土壤生有一层白色絮状菌丝。 2、黄瓜霜霉病。主要发生在叶片上,幼苗期引起枯叶死苗现象。发病初期叶片正面为黄色小斑块,扩大后因受叶脉限制而成多角形不规则的黄褐色斑块,甚至扩及 First, the identification of symptoms l, Cucumber seedling damping off disease. Seedling near the base of the stem was a water circle-like lesions, brown, shrinkage; young leaves withered discoloration before the seedlings fell to death. When the soil is wet, a layer of white flocculent mycelium is born in the soil around the diseased part and diseased plants. 2, cucumber downy mildew. Occurs mainly in the leaves, seedlings caused dead leaflet phenomenon. Early onset of leaves positive for the small yellow patches, enlarged due to restricted by the veins polygonal irregular brown patches, and even expanded