猝倒病是黄瓜苗期主要病害,幼苗期易发生。尤其在温床育苗时,常发病严重。地温低,床土湿度大,晚上太凉,白天光照不足,通风不良等情况均易发病;种子发芽出土后,到小苗展开一片真叶前,是发病的盛期。一般幼苗发病后,根茎部是水浸状病斑,逐渐变黄变褐。近地面处缢缩,子叶颜色变暗,尖部由向斜上方陡立变平展,进而下垂、打蔫,突然枯死。猝倒病开始是个别小苗因病而死,随后以中心病株向四周蔓延,出现一块一块的圆形病区。严重时,幼苗大部或全部死亡。在高温条件下,病苗残体表面及附近土表长出一层白 Damp down disease is the main disease of cucumber seedling stage, seedling prone. Especially in hotbed nursery, often a serious disease. Low ground temperature, bed soil humidity, too cold at night, insufficient light during the day, poor ventilation and other conditions are susceptible to disease; seed germination unearthed to the seedlings to start a true leaf before, is the peak of the disease. After the onset of the general seedlings, the rhizome is flooded spots, gradually turn yellow brown. Shrinkage near the ground, cotyledons darker, sharp tip by the steep slope above the flattened, and then droop, hit 蔫, suddenly died. Dumping disease is the beginning of individual death due to illness, and then to spread around the center of the diseased plants, appeared a piece of circular ward. In severe cases, most or all of the seedlings die. Under the condition of high temperature, the surface of the disease and its remnant surface grow a layer of white