玉米丝黑穗病属种苗侵入系统性侵染的黑穗病。幼苗期多数病株不表现异常,中后期在雄穗上全部或部分分枝被破坏,形成病瘤,外面包有白膜,破裂后露出黑粉,黑粉散出后残留丝状穗轴,有的小花颖壳增生成小叶状。雌穗发病时,基部膨大,端部尖,多不抽花丝,苞叶早枯黄,由一侧裂开,内部全变成黑粉,外有白膜包被,膜破黑粉散出后,残留黑色丝状物,有的仅穗上部受害,基部籽粒变成畸形丛生的小叶状物,内含少量黑粉。雌病穗前期黑粉包在苞叶内不易 Maize head smut belongs to systemic infection of smut. Most of the seedlings did not show abnormalities in the late, all or part of the tassel in the branches were destroyed to form a tumor, the outer envelope with white film, black powder rupture, black powder scattered residual filamentous cob, Some flowers Ying shell hyperplasia into lobular. Egg spike, the base of the swollen, the tip of the tip, not drawing more silk, husk early yellow, cracked from the side, the internal into a black powder, the outer coating of tunica albuginea, black powder broke out after the film, The remaining black filaments, and some only the upper ear damage, the base of the kernel into a deformed cluster of leaflets, containing a small amount of black powder. Females sick early black powder package in the husk is not easy