棉花凋枯病是棉花的主要病害之一。我们地区近年来发生面积逐年扩展,对产量影响很大,一般减产三成,重的五、六成,少数田块甚至无收。我所从一九七二年开始对此病进行了调查研究,现将结果简报如下:一、发病症状:棉叶发病,先从顶端嫩叶开始,离叶脉较远的叶肉组织退绿,(叶脉仍为绿色),肉眼观察不太明显,把病叶对着太 Cotton blight is one of the main diseases of cotton. In recent years, the area in our region has been expanding year by year, which has a great impact on output. Generally, it has reduced the output by 30%, reduced the output by 50% or 60% and even reduced the production of a few fields. I started from 1972 on the disease were investigated and the results are as follows: First, the incidence of symptoms: the onset of cotton leaves, starting from the top of the young leaves, leaf veins farther away from the leaf veins green, (( Veins are still green), the naked eye is not obvious, the sick leaves on the too