何为白菜的三大病害应如何防治０６１００１河北省沧州市郊区农业局米淑玲白菜三大病害是指病毒病、霜霉病、软腐病。白菜病毒病主要在苗期发生，一般６片真叶以前遇高温干旱发病较重。受害幼苗沿叶脉失绿，叶片呈花叶、皱缩、生长缓慢，叶脉上产生褐色坏死斑点或条斑。白... What is the three major diseases of cabbage should be how to prevent 061001 Cangzhou City, Hebei Province, Suburb Bureau of Agriculture Mi Shuling cabbage three diseases refers to the virus disease, downy mildew, soft rot disease. Cabbage virus disease occurs mainly in seedling stage, the general 6 true leaves encountered severe cases of high temperature and drought. Victims of seedling chlorosis along the veins, leaf mosaic, shrinkage, slow growth, brown necrosis of the spots on the veins or streaks. White...