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About the prevention and treatment of cabbage downy mildew
Cabbage downy mildew mainly affects the leaves, initially pale yellow or yellow-green lesions, which are yellowish brown, polygonal or irregular. When the air is humid, a white to grayish frosty mildew layer is produced in the leaf back disease. Early sowing, too dense, poor ventilation, even sputum, lack of fertilizer during the core period, weak growth of the plot, sowing early premature Chinese cabbage often disease serious.
Control measures:
(1) Breeding and selecting resistant varieties according to local conditions.
(2) Heavy disease fields and non-host plants are rotated for more than 2 years.
(3) Strengthen cultivation management. Implement high-narrow and deep-ditch cultivation, timely sowing, reasonable close planting, prevent field closure; apply sufficient base fertilizer, timely topdressing and spraying foliar fertilizer, avoid partial application of nitrogen fertilizer, improve plant disease resistance; moderate watering, anti-large Water flooding and watering at noon on sunny days, water should not be lacking after the heart; the diseased plants are found in the field to be removed in time, the diseased bodies are removed after harvest, and the infection is reduced after flood season.
(4) Seed treatment. Seedless plants are kept seeded and disinfected with seeds. Seed dressing with 25% metalaxyl WP can be used with 0.3% seed weight; or 35% metalaxyl + 50% thiram + 70% thiophanate 5:2:1 Seed dressing, the dosage is 0.4% of the seed amount.
(5) Chemical control. On the basis of good measurement and report, spray the drug to control the disease at the beginning of the disease or when the central disease plant appears, spray 25% metalaxyl WP, or 64% anti-virus sputum, or 58% toxic Mn-Zn WP 500 -700 times solution, or 69% Ankang Zn + 75% chlorothalonil (1:1) 1000 times solution, 3-4 times, once every 10 days, alternately applied, spray evenly. Commonly used agents are: metalaxyl, anti-virus cockroach, toxic toxic manganese Zn, Plex, Kelu, Anke manganese zinc, chlorothalonil.
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