How to prevent watermelon knock-down

Tripartite disease, commonly known as "small feet," is an important disease of watermelon seedlings. The disease is a fungal disease. After the seedlings have been unearthed and the true leaves have not yet been unfolded, they have been infected by the bacteria, resulting in water-stained dark spots at the base of the young stems. The stems then expand around the stems and gradually shrink into thin lines. Lodging due to loss of support. Diseases such as infestation of watermelon seedlings can also cause tripping.

Dongtai, Jiangsu is the hometown of watermelons. During the last year of watermelon seedlings in the greenhouse, there was continuous rain, lack of light, and high humidity in the seedbeds. The local use of a field covered with no drip film to cover seedlings was also serious. The individual farmers even destroyed the seedbeds and replanted the seedlings. According to the author's experience, the prevention and control of watermelon damping-off is the key.

1. Disease occurrence The disease mainly occurs after sowing until the cotyledon has just flattened and the true leaves have not yet been exposed. According to analysis, germs can survive in soil and fertilizer for many years. Low temperature and high humidity are the inducing factors for the emergence of watermelon seedlings. In the process of watermelon seedlings, the following situations are prone to down seedlings: First, seed germination requires sufficient water, melon farmers are inaccurate when growing seedlings, and the cultivation techniques of bitter gourd on yam and yam medicines. Excessive watering causes excessive soil moisture. Second, the melon seedlings are not supported by the seed endosperm to provide nutrients before they are unearthed. Photosynthesis is not available. The resistance is poor. Once susceptible, the seedlings are easily killed. Third, the seedlings are generally not exposed before membrane excavation. The seedbed has high humidity.

2. Prevention and Control Methods To prevent and treat damping-off disease, we should take "prevention-based, comprehensive prevention and treatment" measures.

1 warm soup soaking. The seeds were soaked in hot water at 55°C for 15 to 30 minutes. The temperature at 55°C was the lethal temperature of the germs. After the seeds were soaked, they could basically kill the germs on the surface of the seeds and passivate the watermelon mosaic virus.

2 drug seed dressing. Can be used 30% Dufu WP powder dressing, kill some of the seeds on the surface of bacteria.

3 substrate seedlings. The use of matrix seedlings requires the texture of the matrix to be loose and has good air permeability. After watering, excess moisture can be discharged through the holes below the plug, reducing the humidity of the substrate and reducing the occurrence of diseases.

4 Heating line heating. Heating the electric heating line under the plug tray can not only increase the temperature of the seed bed, promote early-onset seedling growth, but also promote water evaporation and reduce humidity.

5 artificial fill light. In case of continuous rainy weather, or when the light transmittance in the shed is low, an incandescent light can be hung in the shed to enhance photosynthesis and improve the disease resistance of the plants.

6 timely ventilation. In the case of ensuring the normal growth of melon seedlings, the cover was removed during the day and the membrane was ventilated at noon on sunny days to reduce the humidity of the seedbed. When the temperature exceeds 25°C, the greenhouse membrane is opened for ventilation, and the side of the outlet should be exposed when uncovering the membrane to prevent the excessive cooling rate from causing "flashing seedlings" and leading to the failure of stiff seedlings.

7 pharmaceutical control. When the melon seedling leaves have just been exposed and the true leaves have not yet been exposed, 72.2% of Proplohydrate can be used as a 400 times solution or 72% of cymoxanil as 800 times; or 70% of thiophanate-methyl WP 800 can be used. Double liquid plus 75% chlorothalonil WP 800 times spray control, in case of continuous rainy days or high humidity in the shed, can be mixed with dry fine soil applicator.

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