How to prevent and control downy mildew in water spinach? A detailed explanation of practical technical points
1. Practice a 2-to-3-year crop rotation with other vegetable varieties. 2. Before sowing, dress the seed for sterilization at a ratio of 300 g of 35% metalaxyl per 100 kg of seed; 3. In the early stage of the disease, spray with 50% copper metalaxyl wettable powder at 6000 to 7000 times dilution, or with 72.2% Previcur AS at 8000 times dilution, applying once every 7 to 10 days...
1. Practice a 2-to-3-year crop rotation with other vegetable varieties.
2. Before sowing, dress the seed for sterilization at a ratio of 300 g of 35% metalaxyl per 100 kg of seed; 3. In the early stage of the disease, spray with 50% copper metalaxyl wettable powder at 6000 to 7000 times dilution, or with 72.2% Previcur AS at 8000 times dilution, applying once every 7 to 10 days. Reinfection. Rainwater and insects can also spread it; whether seed can transmit it remains to be studied. Cool, damp nights, warm days, heavy fog and dew, and sticky, wet soil conditions favor the occurrence and epidemic of this disease.
3. Control methods
(1) Select disease-free seed and treat the seed: select a disease-free plot for seed production, soak newly purchased seed in 50°C warm water for 25 minutes, then sow after cooling.
(2) Strengthen garden and field management: choose a plot with high terrain, good drainage and good ventilation for planting. Apply sufficient fertilizer and increase the application of phosphorus and potassium fertilizers. Irrigate reasonably and do not let the onion field become too wet. When diseased plants are found, pull them out and bury them promptly. After harvest, thoroughly remove diseased residues, dispose of them in a centralized way, and carry out deep plowing to reduce the source of inoculum.
(3) Chemical control: spray pesticides in the early stage of the disease, once every 7-10 days, for 3-4 consecutive sprays. Commonly used pesticides include 1:1:240-300 Bordeaux mixture, 40% fosetyl-Al wettable powder at 200-300 times dilution, 25% metalaxyl wettable powder at 500-1000 times dilution, 75% chlorothalonil wettable powder at 500-600 times dilution, 65% zineb wettable powder at 500-700 times dilution, 64% oxadixyl, M8 wettable powder at 500 times dilution, and 66.5% Previcur AS at 700-1000 times dilution.