Due to the large temperature and humidity in the greenhouse, the light is weak, and the air flow is slow, and it is almost free from the direct influence of the outside wind and rain. The vegetables grow vigorously and buds are tender and the vegetables are susceptible to pests and diseases. Example: Sustained low temperature, high temperature, easy to bring diseases at seedling stage, excessive application of foliar fertilizers and plant growth regulators such as silk flowers, eggplant, tomato gray mold.
Temperature and humidity conditions during the day:
15 °C -25 °C, relative humidity more than 85% 8 days, tomato susceptible to gray mold.
15 °C to 20 °C, relative humidity more than 80% for 2 days, tomato disease easily occurs.
20°C-35°C, high humidity for 2 days, cucumber downy mildew occurs.
15 °C -22 °C, air relative humidity more than 90%, prone to scab.
When the soil in the greenhouse is between 16°C and 18°C, it is prone to blight when it is dry or when it is rainy.
Grey mildew, high humidity environment. Especially in winter greenhouses, high humidity, low temperature, continuous cropping, cultivation density, the disease is prevalent. The most suitable infection period is from flowering to fruiting.
The incubation period for disease onset is generally 5-7 days. When the relative humidity is 60%, it is not conducive to the occurrence of disease. The main diseases of greenhouse vegetables: Fusarium wilt, bacterial wilt, epidemic disease, powdery mildew, gray mold, damping-off disease, virus disease, root-knot nematode disease, downy mildew and so on.
The main pests are: aphids, diamondback moth, Spodoptera litura, beet armyworm, guava, Liriomyza sativae, and red spider.
Specific prevention measures:
1: During the idle period of the greenhouse, 40 kg of lime nitrogen is applied for 1 mu, and ploughing, irrigation, and mulching of the mulch for 7-10 days (the lime-nitrogen decomposes to produce liquid cyanamide and gas cyanamide, and fungi and bacteria in the soil. And broad-spectrum killing effects such as nematodes). It has good control effect on damping-off disease, cucumber wilt and tomato bacterial wilt disease, epidemic disease, watermelon root knot nematode disease and so on. At the same time, through high-temperature treatment, the eggs in the soil have a strong killing power, especially small insects, such as Liriomyza, red spider and other eggs are eradicated.
The optimum temperature for the growth of Fusarium and mycelium was 25°C, and the lethal temperature was 54°C.
The optimum temperature for high temperature and high humidity for controlling cucumber downy mildew and scab was 45°C for 1 day, 40°C for 2 days, and relative humidity above 80%.
2. Spray the soil with 1000-1500 times potassium permanganate to kill the bacteria in the soil. In the case of soil holding more than 60% of the field water holding capacity, special bactericides such as Lycoperteriol and other fungicides are used to close the shed for 5-7 days, which is effective for killing soil bacteria.
3. Water-saving irrigation technology to control greenhouse humidity.
4. Grafted seedlings can effectively prevent soil-borne diseases and effectively prevent root-knot nematode infestation.
5. Chemical control:
(1) Bacterial wilt: Use agricultural streptomycin and the like.
(2) Early blight and gray mold: chlorothalonil + 72% DuPont Kelu 600-800 diluted liquid.
Botrytis cinerea is susceptible to drug resistance and attention should be paid to alternate rotations.
(3) Downy mildew: At the beginning of the disease, 50% Anke WP is used 300 times, or 72% DuPont Kelue WP 800 is used at 1000 times.
Bacterial tomato soft rot prevention and control should pay attention to the following aspects: 1 pollution irrigation water (open reservoir); 2 artificial wounds, wound healing, stems, lettuce, lettuce and other residues; 3 insects spread.
(4) Anthrax, powdery mildew: 70% thiophanate-methyl WP, 500 times.
(5) Pest control
For locusts and thrips, 20% of 20% imidacloprid wettable powder is used.
Melon and Liriomyza spp. were sprayed with a 48% Losbuin 1000 times spray.
Spodoptera litura was sprayed with 3500 sprays of 15% liquid detergent.
Plutella xylostella was treated with dish hi.
Red spider can be used 1000 times.
Liriomyza is controlled with avermectin 2500 times.
Root knot nematode disease can be used for a hundred times bellling roots.
6. At present, there is an upward trend in the occurrence of diseases in greenhouses, and attention should be paid to early prevention.
(1) watermelon, melon: Fusarium wilt, anthrax, powdery mildew.
(2) Tomato: Bacterial wilt, leaf mold.
(3) Cucumber: Downy mildew, Sclerotinia.
(4) Spring cabbage: soft rot disease.
7. Identify the main physiological diseases in the greenhouse.
(1) Calcium deficiency; (2) Boron deficiency; (3) Magnesium deficiency; (4) Fertilizer harm; (5) Harmfulness to medicine; (6) Wet harm.
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