玉米霜霉病是热带、亚热带地区的毁灭性病害。美国早在1916年就对玉米霜霉病有了检疫规定,禁止从东方进口玉米。一些非洲国家、澳大利亚等国也先后制定了类似的检疫法规。我国在1986年将玉米霜霉病 Pe-ronosclerospora spp.列为进口植物检疫对象。在自然界中侵染玉米的霜霉病菌有三个属9个种(见表1)。霜指霉属 Peronosclero-spora 的四个种在其发生地区严重威胁玉米生产。如高粱霜霉病.P.sorghi 1969年在美国得克萨斯州流行,使玉米高梁的产量损失 Downy mildew in corn is a devastating disease in tropical and subtropical regions. As early as 1916, the United States had quarantined maize downy mildew and banned the import of corn from the east. Some African countries, Australia and other countries have also enacted similar quarantine regulations. China in 1986 corn downy mildew Pe-ronosclerospora spp. As imported plant quarantine object. There are three genera and 9 species of downy mildew that infect maize in nature (see Table 1). Four species of frost-pollinating Peronosclero-spora are a serious threat to maize production in their area of ​​occurrence. Such as sorghum downy mildew.P.sorghi 1969 in the United States, Texas prevalence of corn sorghum yield loss