Integrated control of cucumber downy mildew in protected area

Cucumber downy mildew, commonly known as horseshoe dry, is a serious epidemic disease of protected and open cucumbers. It can be affected throughout the growth period. It is characterized by rapid spread and serious disease, which can kill most of the leaves in a few days, causing serious damage. Reduce production, and even refuse. Pathogens are mainly transmitted by air currents. High humidity is an important condition for its occurrence. The onset temperature is 16 to 24 ° C, and the optimum relative humidity is 85% or more. When the temperature is lower than 15 ° C or higher than 30 ° C, the disease is inhibited. The relative humidity of the air is below 50% to 60%, and the pathogen cannot produce sporangia. Making full use of the controllability of the protected environment and rational use of agro-ecological control techniques can effectively control the occurrence of downy mildew.
Agricultural control: 1. Choose disease-resistant products. This is the most economical and effective way to control cucumber downy mildew. For example, greenhouses, greenhouse delay cultivation or greenhouse wintering cultivation, cucumber growth period is mostly the peak period, should choose the strong disease resistance of autumn shed No. 1, Jinza No. 1, Jinchun No. 3, Lu Cucu 10 and other varieties In the early spring cultivation of protected areas, it is necessary to select varieties such as Jinchun No. 2, Jinza No. 2, Zhongnong No. 5 and Lu Cucu No. 4 which are resistant to disease, low temperature, low light and premature. 2. Rational fertilization, scientific watering. Add organic fertilizer and apply it with reasonable formula of nitrogen, phosphorus and potassium fertilizer to cultivate strong seedlings and strong plants to improve the disease resistance of the plants. The melon is weak or the leaf color is light and should be sprayed with 0.2% urea and 0.3% potassium dihydrogen phosphate or photosynthetic micro-fertilizer. After pouring the planted water for about 7 days, it will not be watered, and the number of watering will be controlled from the slow seedling to the flowering period. The irrigation is carried out in the sunny morning, after which the shed can be closed, the room temperature is raised to about 30 °C, and the air is kept for 1 hour and then ventilated; the temperature drops below 25 °C, and then the temperature is raised once and then released, the disease prevention effect is better. . 3. Clean the countryside. Remove the diseased leaves and the bottom, yellow and old leaves of the plants in time. After harvest, all vegetable residues, leaves and weeds are removed in a timely and thorough manner. Remove all hosts from the germs to reduce the incidence of the disease.
Ecological control: 1. No drop film is selected. The drip-free film has the advantages of no dripping, heat preservation, light transmission and aging resistance, can reduce the humidity in the protection ground, and improve the lighting conditions, thereby achieving the control effect. 2. Hang the reflective screen. The reflective curtain is hung on the north side of the greenhouse spine to enhance light, increase temperature and reduce humidity. Generally, the temperature is increased by 1 to 2 ° C, and the relative humidity of the air is reduced by 3% to 4%. 3. Adopt sub-film drip irrigation technology. It adopts large ridge double row planting, inter-row filming, film watering, and conditional best under-film hose drip irrigation.
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