玉米丝黑穗病群众称为灰苞、火烟苞。是由担子菌纲、黑粉目、黑粉料、轴黑粉属的真菌所引起。通常是从种子萌发至五叶期病菌侵入并在植株生长锥潜伏下来,待植株花芽分化阶段急速繁殖而为害花器。便雄穗与比雌穗纤维成丝状,形成大量黑粉,故称丝黑穗病。我县一九七九年以前很少发病。一九七九年春末夏初大旱,此病暴发成灾。仅郑场区70％以上的玉米面积发病,平均发病率达到15—18％,感病品种新单6号发病率29.5％全区近万亩玉米受害,损失产量六、七十万斤。一九八○年平均发病率为3—4％, Corn smut masses called gray bud, fire smoke bracts. Caused by the Basidiomycetes, black powder, black powder, black fungus fungus caused. Usually from the seed germination to the five-leaf germs invasion and lodging in the plant growth cone down until the plant flower bud differentiation rapid propagation and harm flower. The tassel and ear fiber filaments than the formation of a large number of black powder, so that the head smut. I County incidence rarely before 1979. In the spring of early spring and early summer of 1979, the disease broke out. Only Zheng area 70% of the maize area incidence, the average incidence rate of 15-18%, the susceptible variety Xin Dan 6 incidence of 29.5% of the area nearly ten thousand acres of corn victims, the loss of yield six, 700,000 kg. The average incidence in 1980 was 3-4%