葡萄霜霉病是葡萄生产中的一种严重病害。轻则减产、重则整枝死亡。此病主要危害叶片、其次是新梢、花序和幼果等幼嫩组织。被害叶片开始出现半透明油渍状病.以后变为黄绿色,大小不一,边缘界限不明显,严重时叶焦枯、脱落。花穗、幼果若感病则呈深褐病斑,后期发生灰白色霜霉后不久即干缩脱落。该病一般在7、8月开始发病、9、10月为发病盛期。其发生和危害程 Grape downy mildew is a serious disease in grape production. Light cuts, heavier pruning death. The disease mainly leaves, followed by shoots, inflorescences and young fruit and other young organizations. The victim leaves began to appear translucent grease-like disease later became yellow-green, the size of the edge of the margin is not obvious, serious leaves scorched, fall off. Spikes, young fruit if the disease was dark brown spot, the latter gray-white downy mildew soon after shrinking off. The disease usually begins in July and August, September, October is the peak incidence. Its occurrence and endangerment process