在多雨的1975、1977年,江汉平原棉区棉苗疫病发生,造成大量缺苗和死苗。从4月底至6月上旬,一般补种4—6次。到后期,在湿度高、温度低的棉田,棉铃疫病也发生较重。症状棉苗子叶先受侵染,在病部出现深青色水浸状,然后变成青褐色,最后发展成为黑色油光状,致使幼苗倒伏枯死。潮湿时,枯苗表面布满黄白色的绵毛状物。有真叶的幼苗,先是发病的两片子叶下垂,天气转晴后,病子叶焦枯脱落,真叶和幼茎逐渐变黑枯死(见图)。铃疫病起初在病部出现青色水浸状,逐 In rainy 1975 and 1977, cotton seedling blight occurred in Jianghan plain cotton area, resulting in a large number of lack of seedlings and dead seedlings. From the end of April to early June, the general replanting 4-6 times. To late, in the high humidity, low temperature cotton fields, bollworm disease also occurred heavier. Symptoms of cotton seedlings first infested with dark green in the disease flooded like, and then turned into a greenish brown, and finally developed into a black shiny shape, resulting in seedlings fall dead. Wet, dry seedling surface covered with yellowish white fleece. There are real leaves of seedlings, the first two leaves of the disease ptosis, the weather became fine, the cotyledons scorched off, true leaves and young stems gradually black dead (see photo). Bell disease at the beginning of the disease appeared cyan flooded, by