大白菜霜霉病俗称”烘叶”“白霉”等。是北方地区大白莱的主要病害之一,一旦发生,常给生产上造成严重损失。 一、症状 大白菜霜霉病主要为害成株期叶片,也能为害幼苗、留种株茎、花薹及种英。苗期受害,初期正面无明显症状,叶背面有白色霜状霉层,后期苗叶发黄,整株枯死。成株期受害,初期呈现淡绿色水浸状斑点,叶正面不表现症状,随着病情 Cabbage downy mildew commonly known as “drying leaves” “white mold” and so on. It is one of the major diseases in the northern region and causes serious losses to the production once it occurs. First, the symptoms Cabbage downy mildew is mainly harmful to adult leaves, but also damage seedlings, plant seed stems, flower stalks and species of British. Seedling victims, the initial positive no obvious symptoms, the back of the leaves have white mold mildew layer, yellow leaves later stage, the whole plant died. Adult damage, the initial pale green flooding-like spots, the positive leaves do not show symptoms, with the disease