The reader of Linyi County with the cell phone ending number 2849 asked him to plant 2 acres of lettuce. How to prevent downy mildew?
Chen Yunqi A: Lettuce is a kind of salad that people like to eat. It grows lettuce, has a small investment, and has quick results. In summer, the temperature is high, the rain is heavy, and the humidity is high. Downy mildew is a major disease that damages lettuce in summer. It is necessary to pay attention to timely prevention and treatment.
First, the symptoms
The disease mainly damages the leaves of lettuce and spreads upward from the lower leaves of the plants. Initially, the leaves have yellowish-yellow-circular or polygonal lesions. When wet, white mold grows on the back of the leaf, sometimes white mold will spread to the front of the leaf, the latter stage of the disease will turn into yellow-brown and become a piece, causing the whole leaf to dry.
Second, the incidence of the law
The disease is a fungal disease. Mycelium is transmitted by wind and rain or insects. The bacteria are invaded by the epidermis or stomata of lettuce. The infection temperature is 15-17°C. The disease is susceptible to disease when it rains, when the soil is wet or when it is poorly drained.
Third, prevention and control measures
1. Agricultural measures. Properly dense planting, pay attention to drainage, reduce the humidity in the field. Implement a 2-3 year rotation, pay attention to clearing the garden in time, and remove diseased leaves and diseased plants in a timely manner.
2. Chemical control. Available 25% metalaxyl WP 800 times, or 72.2% Precike 600 times, or 90% schisomide WP 500 times, or 58% rosin MnZn WP 500 times , Or 72% Kelu wettable powder 700 times, or 72% cream Kang wettable powder 800 times, or 72.2% wet mildew Wei agent 600 times, or 56% wet mildew wet powder 700 times, Spray once every 7 days, continuous prevention and treatment 3-4 times. To prevent drug resistance, the above pesticides can be used interchangeably.
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