稻粒黑粉病（又叫黑谷）是杂交水稻制种田中一种较普遍发生的病害，一般病粒率达5％左右，严重田块达30％以上，不仅影响杂交水稻制种田的产量和质量，而且影响杂交水稻的推广。一、影响发病因素1不育系的开花习性凡开花时间长，颖壳张开角度大、柱头外露多的威20A等不育系株发 Rice powdery mildew (also known as black valley) is a more common disease in hybrid rice farming, the general rate of about 5% of the disease, severe block up to 30%, not only affects the yield of hybrid rice farming And quality, but also affect the promotion of hybrid rice. First, the impact of disease factors 1 flowering habits of male sterile lines where flowering time is long, glume open wide angle, stigma exposed more Wei 20A and other sterile lines