Grape downy mildew mainly damages the leaves, shoots, buds and young fruit of grapes. It usually starts from June to July and reaches its peak in September. In the early stage of disease, irregular yellowish translucent, oil-like spots appeared on the front of the leaves and gradually expanded into yellowish-brown lesions with no obvious edge boundaries. More than a few small spots connected to an irregular or polygonal lesions, and in the back of the leaves produce a layer of gray mold, later turned light brown, the leaves lose water, dry coke and curl, severe leaves will fall off . The prevention and treatment of pharmaceuticals is mainly prevention. In the early stage of disease, a small amount of Bordeaux mixture is sprayed every 10 days for protection. When sporadic spots are found, the DuPont Fuxing Star is 8000 times liquid; after extensive onset, it should immediately spray 25% metalaxyl WP 600-700 times; or Dasheng M-45 plus BPh. When spraying, pay attention to the lower part of the leaf and the back of the blade. At the moment of peak incidence, precautions should be taken until the defoliation. Each use of pesticides can be added to the fruit tree-specific Tianda 2116 to enhance the photosynthesis of the leaves, increase the accumulation of organic matter, and increase their ability to overwinter.
