The production of greenhouse vegetables satisfies people's demand for buying fresh vegetables in winter, but today, food safety has received much attention. The quality of agricultural products from farmland to table is particularly important. Therefore, in the greenhouse vegetable production process must be implemented in accordance with the pollution-free production of technical regulations to ensure that people buy vegetables. In the production of cucumbers in greenhouses, downy mildew is the main disease affecting the yield and quality of cucumbers, commonly known as “running horses.” After several years of exploration, the Agricultural Technology Center of Yang County, Shaanxi Province, China Agricultural Network Technology Group summarized a set of Based on the implementation of agricultural prevention and control, taking ecological control as the core and assisting in the pollution-free prevention and control technology of chemical prevention and control, how to prevent and control cucumber diseases and insect pests in greenhouses has achieved good results.

First, the main symptoms

Cucumber downy mildew mainly damages the leaves. In the early stage of disease, there were yellow and green spots on the surface of the leaves, which gradually expanded to form polygonal yellow-brown patches by the veins. The disease spread from the bottom to the top, and the whole plant died when it was severe. When the humidity in the shelter is high, the Minister of Backstain Disease produces a gray moldy layer.

Second, prevention and control measures

(a) Agricultural control

1. The primary infestation source of cucumber downy mildew in crop rotation crops is the downy mildew of cucumber or soil in the soil. Therefore, it is advisable to use crops such as summer radish and bitter gourd for the cucumber in the greenhouse to avoid continuous cropping.

2. Good varieties should be selected for high-quality hybrids with strong disease resistance, high yield, and suitable for greenhouse cultivation, such as Jinyou No. 2, Jinza No. 3, and Jinchun No. 4.

3. Cultivate strong seedling beds separate from production greenhouses and disinfect bed soil, strictly control sowing density, strengthen seedbed management, ventilate and ventilate, increase light, control seedlings to grow long, and cultivate disease-free strong seedlings. Before the planting, 75% chlorothalonil wettable powder can be sprayed 500 times, colonized with drugs, and diseased and weak seedlings can be completely eliminated.

4. Canopy disinfection 10 days before colonization of cucumbers, the first time after pupa formation, closed the greenhouses for 5 to 7 days and use high temperatures to kill pathogens in the shed.

5. Formula fertilization: Prepare 6,000 kg of organic fertilizer per acre. Accumulate plastic film two months in advance. After fully fermenting and decomposing, apply 30 kg of urea, 15 kg of diammonium, and 50 kg of potassium sulfate as base fertilizer. The melon period combined with subsurface dark irrigation was divided into 3~4 times with nitrogen topdressing. In the middle and later stages of cucumber growth, spraying 0.5% urea, 0.2% potassium dihydrogen phosphate, and 0.5% white sugar mixture on the leaves can rapidly increase the total sugar and nitrogen content in the green functional leaves and increase the physiological resistance of the leaves.

(II) Ecological Control

In order to control the temperature and reduce the humidity, it is required that the cucumber leaves have no condensation or condensation for more than 2 hours.

1. Temperature-based control of disease occurrence. After the sunrise in the morning, the grasshoppers were opened and the shelf temperature was raised to 25~32°C as soon as possible. Then, the ventilation was cooled and the humidity was lowered, and the relative humidity was controlled at about 75%. If the temperature of the greenhouse is not too low in the morning and the relative humidity is relatively high, it can be ventilated and dehumidified, and then the greenhouse can be warmed up.

2. The relative humidity controls the occurrence of the disease. The afternoon temperature dropped to 25~20°C and the relative humidity was controlled at about 70%. The shed shall be covered with a plastic film; watering shall be carried out in the morning on a sunny day, adopting under-membrane under-irrigation techniques, and pouring small water.

3. Alternately control the occurrence of disease with temperature and humidity. The greenhouse is closed at about 20°C in the evening. Before the cover grasshopper can be re-ventilated according to temperature and humidity. The minimum temperature at night can be reduced to 15°C to 12°C (20°C to 15°C in the middle of the night and 15°C to 12°C in the middle of the night). If the minimum temperature outside the night shed is above 12°C, it can be wet overnight.

4. High temperature stuffy sheds inhibit disease occurrence. When the downy mildew began to spread, it was selected to seal the greenhouse at noon on sunny days, so that the temperature of the upper part of the cucumber vines rose rapidly to 43-45°C, and after 2 hours, it was cooled and cooled slowly. The morning or the morning of the dungeon should be filled with small water in the morning.

(three) supplemental application of CO2 prevention

After the sunrise, the CO2 is cast so that the content of CO2 in the air in the shed is kept at 1000-1500 mg/kg on sunny days and kept at 500-700 mg/kg on cloudy days. This allows the green functional leaves to maintain vigorous photosynthesis and reduce and reduce downy mildew. The occurrence of the disease.

(d) Chemical Control

In the seedling stage and the early stage of disease, the bacillus subtilis WP of 2000 to 2500 times per gram of live spores is sprayed, or the 45% chlorothalonil smoke agent 200 to 250 grams per gram is used to smoke after the closing of the shed in the evening. Prevention. When the humidity in the shed is relatively large, the mu is sprayed with 5% chlorothalonil dust and 1 kg of dust. When the greenhouse is warmed up during sunny mornings, 40% EB aluminum wettable powder can be sprayed at 200-250 times.

Other Chemicals

Formula: CH3CHOHCOOH Molecular weight: 90.08 Performance:It is colorless transparent viscidity liquid, mild acid, guide wetly; the aqueous solution shows the acid reaction. It can be mixed with water, ethanol or ether wantonly, but not dissolved in chloroform. Specification:80%, 88% Packing:25kg drums, 250kg drums, IBC plastic drums. Main use: This product has characteristics, such as hot stability natural purely with soft and certain tart flavor,etc. Widely used in the food,pharmaceutical,electroless plating industries,etc.

Other Chemicals,Epichlorohydrin (Ech),Lactic Acid 80%

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