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葡萄霜霉病在各葡萄产区均有发生,是葡萄的主要病害之一。幼苗感病后,叶片枯焦,新梢生长停滞,枝条不能成熟,如果成株发病引起早期落叶,削弱树势,影响当年的葡萄产量。 1.病害症状主要危害叶片,也能危害新梢、卷须、叶柄、幼花序、果柄和幼果。叶片受害在其上边产生边缘不清晰的水渍状淡黄色小斑,随后渐变淡绿至黄褐色多角形病斑,病斑逐渐形成不规则形斑块。天气潮湿时.于病斑背面产生白色霜霉状物,发病严重时病叶枯焦,早期脱落。嫩梢受害,初生水清状,略凹陷的褐色病斑,天气潮湿,病斑上产生稀疏的霜霉状物,后期病组织干缩、新梢生长停滞、扭曲枯死。卷须、叶柄、幼花序也能受害,其症状与新梢类似,于病部产生霜霉。如若早期侵染,则最后变褐、干枯及脱落。幼果受害,病部褐色,变硬下陷,上生白色霜状霉层,易脱落。半大果粒受害,病部褐色至暗褐色,软腐,但在果粒表面很少产生霜霉,萎蔫后脱落。果实着色后不再被侵染。
Grape downy mildew occurs in all grape producing areas, is one of the major diseases of grapes. Seedlings susceptible, the leaves coking, shoot growth stagnant, shoots can not mature, if the incidence of adult plants caused by early deciduous, weakening the tree vigor, affecting the year’s grape production. 1. Symptoms of disease The main hazards of leaves, but also endanger shoots, tendrils, petiole, inflorescence, stalk and young fruit. Leaf damage on its edge to produce a clear watery yellowish spot, followed by gradual light green to brown polygonal lesions, lesions gradually formed irregular shaped plaque. When the weather is wet, it produces white downy mildew on the back of the lesion. Shoot damage, nascent clear water, slightly concave brown spots, wet weather, mildew sparse mildew on the lesion, the late shrinkage of tissue disease, the growth of new shoots stagnate, distorted dead. Tendrils, petiole, inflorescence can also suffer from the symptoms similar to the new shoots, in the Ministry of disease downy mildew. If early infection, the last brown, dry and fall off. Young fruit victims, sick brown, hardened sag, white cream creamy mold layer, easy to fall off. Half of the fruit damage, disease brown to dark brown, soft rot, but rarely produced in the fruit surface downy mildew, wilted off. The fruit is no longer infected after coloring.