Rape mildew control method
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The downy mildew of rape can occur from the seedling stage to the flowering and podging stage, which damages the leaves, stems, flowers and fruits and affects the yield and quality of rapeseed. First, the symptoms of cotyledon incidence of back green lesions. In the early stage of the onset of the true leaves, pale green patches appeared on the front of the leaves, gradually expanded into polygonal or irregular shapes, and a white mold layer grew on the corresponding back surface. Severely damaged leaves turn yellow, and even dry and fall early. Pedicel swelling after infestation does not result. Second, prevention and control methods (a) agricultural control. 1. Choose high-yield and disease-resistant varieties. 2. When a squid is found to be swollen, it should be cut off promptly and taken out of the field or buried deep. 3. Open ditch drainage dehumidification, cultivating loose soil, reduce bacteria source. (b) Chemical control. At the seedling stage, a 1:1:200-fold Bordeaux mixture is sprayed on the back of the leaves to control 1 or 2 times. In the early flowering period, when the diseased leaf rate reaches 10%, the first prevention and treatment will be carried out, and the disease will be prevented and treated once every 5 to 7 days. If there is more rainy weather, it is better to control 3 times. The commonly used agents are 50% Rhodoxenicillus wettable powder 800 to 1000 times liquid, 75% chlorothalonil wettable powder 600 times liquid.