Prevention and control of Sclerotinia sclerotiorum caused by brown rot of diseased tissue

Sclerotinia sclerotiorum

1. Characteristics of symptoms:

After the seedlings were susceptible, the cabbage leaves appeared water-immersed light brown disease spots, the edge was not obvious, and the soft rot of the diseased tissue caused quenching. During the pericardium period, waterlogged sunken spots were produced near the surface of the vegetable side and the base of the stem, which began to show light brown, then turned brown or grayish white, and the affected site rotted. When the environment is humid, the disease site has long white villi and black-brown mycelium, forming black mouse dung-like sclerotia. At the base of the stem, the disease spot ringed the stem, and the whole plant died a week later.

Second, the regularity of the disease:

Sclerotinia sclerotiorum (Sclerotinia sclerotiorum) is a fungal disease caused by Sclerotinia sclerotiorum. Sclerotia do not need to dormancy. Under moist conditions, sclerotia can germinate, produce ascospores and spread by airflow. The most suitable temperature for pathogen development is 20 ℃. The hyphae or ascospores produced by sclerotia spread in the field with wind, rain or irrigation. Low temperature, low light, rainy and humid, and the disease occurred seriously. Excessive application of nitrogen fertilizer, low-lying terrain and poor drainage are all conducive to the occurrence of the disease.

3. Prevention and control methods:

1. Agricultural prevention and control. Before sowing, the cabbage seeds are rinsed with 10% salt water or 10% 20% ammonium sulfate, dried and sown. Before sowing, setting the temperature of the seedling bed to 55 ℃ for 2 hours could kill the sclerotia in the soil. Cabbage and cruciferous crops were rotated for 2-3 years. Dig deep into the soil and bury the sclerotia that remain on the surface below the soil layer 10cm. Apply sufficient base fertilizer, increase phosphorus and potassium fertilizer, not partial application of nitrogen fertilizer. Strengthen drainage to make the soil moderately dry. When diseased plants are found, pull them out in time, and take them out of the field, burn them or bury them deeply. When watering, small water should be watered frequently to prevent flooding.

two。 Chemical control. In the early stage of the disease, it is necessary to spray in time, focusing on the base of cabbage stem, old leaves and ground. Each mu can be mixed with 2 to 2.5 kilograms of 5% ammonium chloride powder and 15 kilograms of fine soil and sprinkled between the rows. Spray 50% Sukeling wettable powder 2000 times or 40% sclerotia net wettable powder 1000x 1500 times or 50% prohydantoin wettable powder 1000 times, spray once every 7 times 10 days, spray 2 times 3 times.