Gray mold of cucumber is harmful to flowers, young melons, stems and leaves. Harm to melon flowers and young melons is the most common. At the early stage of the disease, the pedicel of young melon was waterlogged, the color changed gradually, and the diseased part became soft and rotten. When wet, the surface of the diseased spot is densely covered with gray-black mold, petals wither and fall off, melon branches stop growing, and melon tips rot. When the leaves are diseased, the germs mostly start to infect from the edge, and the diseased spots develop into leaves in a V shape, and there are inconspicuous wheel marks on the diseased spots; Leaf disease, the lesion is flooded at first, then turns to light grayish brown, and sometimes there is gray mold in the middle. The diameter of the lesion is 0.2 ~ 0.25 cm, and its edge is obvious. Sometimes there are inconspicuous wheel lines on the lesion. The stem was diseased, the diseased part festered, the surface was covered with gray-brown mildew spots, and the front melon vine broke and died.
Botrytis cinerea is caused by Botrytis cinerea, a subfamily of fungi. The optimum pathogenic temperature of botrytis cinerea is 18 ~ 23℃, with the highest temperature of 32℃ and the lowest temperature of 4℃. When the humidity is above 90%, the disease becomes serious.
(2) prevention and control methods.
The plant protection policy of "prevention first, comprehensive management" should be carried out to control cucumber gray mold.
① selecting disease-resistant varieties; Grafting seedling, strong seedling planting; Pay attention to rotation with non-melon crops; Increase the application of biological bacteria organic fertilizer, phosphorus potassium fertilizer and trace element fertilizer, reduce the use of nitrogen fertilizer, and prevent melon seedlings from growing in vain; Adjust the relationship between vegetative growth and reproductive growth, maintain the robust growth of plants, and improve the disease resistance of plants themselves.
② Adjust the ecological environment. Field cultivation should be carried out in the north-south direction, appropriately increasing row spacing, improving ventilation conditions and reducing microclimate humidity in the field; Protected cultivation, high temperature management (30 ~ 35℃) during the day, increased ventilation at night and low temperature management (10 ~ 16℃) can reduce indoor air humidity, create unsuitable environmental conditions for the infection and development of gray mold, and control the occurrence of diseases.
(3) Remove the diseased leaves in time, and bury all kinds of sick and disabled bodies immediately. It is strictly forbidden to litter, spread germs and spread diseases.
④ Chemical control. It is best to choose the special melon and eggplant fruit of Tianda 2 1 16 and add the following fungicides, but it is not suitable to mix with alkaline chemicals.
50% Kaiser water dispersant 1500 ~ 2000 times, 10% sego 2000 times, 99% tianda Meilin 3000 times, 50% chlorpheniramine 800 times, 50% prochloraz 800 times and 25% Amisi 2500 ~ 3000 times. For greenhouse cultivation, 5% Wanmeiling powder can be used for powder spraying control per mu of greenhouse 1000g, or 25% botrytis cinerea smoke suppressant and 45% gray wolf smoke suppressant can be used for smoke control with 300-400g per mu of greenhouse.