What Is Grape Downy Mildew? A Detailed Guide to Grape Management Techniques
What is grape downy mildew? What harm does downy mildew do to grapes? How do you prevent and control grape downy mildew? Netizens, we at Zhidao Zhongdi Wang have summarized the harm and control methods of grape downy mildew, and they are listed below for your reference. The harm of downy mildew to grapes: grape downy mildew mainly damages leaves...
What is grape downy mildew? What harm does downy mildew do to grapes? How do you prevent and control grape downy mildew? Netizens, please help guideZhongdi Wang has summarized the harm and control methods of grape downy mildew, and they are listed below for your reference.
The harm of downy mildew to grapes:
Grape downy mildew mainly damages leaves, and also damages new shoots, flower buds, young fruit and other tender parts. Irregular, pale yellow, semi-transparent, oil-stain-like small spots appear on the upper surface of the leaves, gradually expanding and turning yellow-green, with indistinct edges; several small spots often join into one irregular or polygonal large lesion, and a yellow-white downy mold layer forms on the underside of the leaf, with the lesion turning light brown in the later stage.
Oil-soaked lesions also appear on young grape shoots, with a yellow-white moldy surface, but sparser than on leaves. In the early stage of infection on young fruit, the diseased part turns light green; in the later stage the lesion turns dark brown and sunken, producing a layer of downy white mold, and the fruit becomes hard and shriveled.
Control methods for grape downy mildew:
1. During the growing season and when pruning in autumn, thoroughly remove diseased branches, leaves and fruit, carry them out of the field and burn them in a centralized manner.
2. Timely prune excess lateral shoots and foliage to create good ventilation and light conditions.
3. Before grapes develop the disease, spray a small amount of Bordeaux mixture once about every 10 days for protection. After the disease appears, promptly spray for control with 50% captan 500-times solution, or 65% zineb 500-times solution, or 25% metalaxyl 800-1000-times solution.
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