Occurrence and Control of Cucumber Botrytis cinerea

In recent years, with the continuous expansion of cucumber cultivation area in protected areas, Botrytis cinerea, as a secondary disease, has gradually become a major disease, and poses a serious threat to production. If it is not controlled in time, it will cause great losses. According to the investigation in Zaocheng District, Wuyi, Jizhou and other places, the loss is generally 15% to 20% when the disease occurs, and more than 30% when it is prevalent. The disease not only harms cucumbers, but also harms many kinds of vegetables, such as tomato, eggplant, bean, pepper and so on. Therefore, attention must be paid to the prevention and treatment of this disease in production. First, symptom identification: the disease is mainly harmful to melon strips, leaves and stems at the adult stage. Melon strips and many young melons suffer, most of which are caused by the residual flowers first, and then harm the tip of the melon and expand to the upper part, and in serious cases, half of the melon strips or even the whole melon strips become ill. The disease parts of melon strips turn brown, rot, and there is a dense gray mildew layer on the surface, and the damaged residual flowers or diseased melons falling off to the leaves or stems can cause the disease of leaves or stems. Leaf disease, mostly to the residual flowers as the center, spread around, forming a large near-circular spot, a small amount of gray mildew layer on the surface. Fall on the stem vine, so that the stem vine is broken, and in serious cases the whole plant dies. Second, the pathogen: Botrytis cinerea is caused by Botrytis cinerea. The disease is the source of primary infection by mycelium or conidia attached to seeds, residual bodies, residual soil, or spores from other host gases. The second infection spread through airflow, Rain Water and agricultural operations. Third, the condition of the disease: 3.1 the suitable temperature for the development of the bacteria is 18 ℃ ~ 23 ℃, the relative humidity is more than 90%, and the weak light is the suitable condition for the disease. 3.2 many cloudy days, low temperature, high humidity in the shed, long dew time, when the wind does not wear clothes, Botrytis cinerea will occur seriously. Fourth, prevention and control measures: to control and adjust the relative temperature of the protected land during the melon-setting period and the timely, reasonable and rotational use of pesticides: 4.1 do not have low-lying water in the melon land, prepare deep ditches and high beds, and it is best to cover plastic film for planting; in field management, attention should be paid to timely introduction of vines and removal of excess side branches to ensure good ventilation and light transmission in the field during the melon-bearing period. Attention should be paid to opening side windows and skylights regularly to lower the temperature in protected areas during the melon-bearing period. 4.2 in order to reduce pathogens and keep the field clean, diseased leaves, yellow leaves, diseased flowers and diseased melons should be removed in time 5-7 days before melon festive season. 4.3 appropriate pesticides were used to control the disease at the initial stage of the disease. 4.3.1 20% Chlorothalonil smoke, 300g per mu, 1000 times, 4.3.22% Chlorothalonil, 200g per mu, kindled in the lowest part of the shed in the evening, 4.3.4 50% propofol 1500 times, 4.3.565% promethomyl 1500 times 4.3.640% Baikening suspension 600x 800 times, 4.3.770% Prozac WP 800x 1000 times, 4.3.58% Gray Biqing WP 800x 1000 times, 4.3.9 28% Chlorothalonil WP 800 times. The above chemicals can be used alternately or in combination, once every 7-10 days, continuously for 2-8 times. 5. in order to improve the drug effect in the process of chemical spray prevention and control, we should pay attention to the following points: 5.1The spray should be carried out in a sunny day, ventilated before spraying, and then sprayed after the foliar droplets are air-dried, usually before 10:00 in the morning and after 16:00 in the afternoon. 5.3 when spraying, be sure to spray upward from the lower part of the cucumber seedlings, focusing on the back of the leaves. 5.4 when spraying, the spreading agent should be added properly, such as high fetal membrane, so that the liquid is uniformly attached to the plant, so as to improve the control effect.