Occurrence characteristics and prevention methods of tomato damping-down

Occurrence characteristics of tomato damping-off:

The disease is caused by the infestation of the fungus Pythium aphanidermatum (Eds.) Fitzp. The oocysts stay on the ground for winter with the diseased bodies. When conditions are suitable, the oospores germinate, the germ tubes are generated, and the buds are directly invaded, or the spore bursa is formed after the top of the bud tube expands, and the spore sac is caused by zoospores through wind and rain or irrigation water. Caused initial infection. When the humidity is high, the sporangia and zoospores produced by the diseased area re-infect.

Bacteria like high temperature, high humidity environment, but the temperature requirements are not strict. The main onset in Zhejiang and the middle and lower reaches of the Yangtze River is from February to April. Sensitive growth period in the seedling stage.

Seedbed continuous cropping, low temperature in the shed, high humidity, sown seeds, poor light, poor ventilation, and extensive management of the disease are heavy. In the early years of the year, the incidence of cold and rainy weather was high in early years.

Prevention points

1 seedbed selection: should choose more than three years have not been planted eggplant vegetables, high dry terrain, drainage is convenient, fertile soil, leeward sunny field for seedbed.

2 seed disinfection: dry seeds with 25% metalaxyl powder plus 70% mancozeb (9:1) 1 500 ~ 2000 times liquid dressing, seed surface moisture is appropriate, dosage is 0.4% of seed weight Soaking for 15 to 30 minutes, rinsing with water after 2 or 3 times, drying or germination.

3 bed soil disinfection: 25% metalloxane wettable powder per square meter, 9 grams plus 70% mancozeb WP 1 gram fine dry soil 5 kg mix, before the application of the seedbed water Well, and once drenched, after the infiltration of the water, first spread 1/3 of the well-mixed medicine on the surface of the bowl, and sow the rest of the 2/3 of the medicine soil over the seeds.

4 Strengthen seedbed management: A deep ditch is set around the seedbed to facilitate drainage and lowering of the groundwater level. The temperature and humidity of the seedbed can be reasonably controlled. When the humidity of the seedbed is too high, a layer of dry fine soil can be sprinkled to absorb moisture; the fertilizer and water should be small and small. Lightly pour, while paying attention to timely and moderate ventilation. Strengthen the investigation, remove diseased seedlings and dead seedlings in time, and concentrate or burn them deeply.

5 Pharmacy control: In the early stage of onset, the drug should be administered in a timely manner, sprayed once every 7 to 10 days, and used once every two or three times, depending on the development of the disease. Drugs can be used 68% Jinlei water dispersible granules 600 to 800 times, 75% chlorothalonil WP 600 times, or 50% DLK WP 1000 times, or 80% of Dasheng M-45 can Wet powder 600 times liquid, spray control.