Matters needing attention in planting and watering and topdressing to prevent diseases of lettuce in greenhouse

Lettuce

First, grasp the planting time. Lettuce is usually raised around the Autumn Equinox in the first year and planted by the Beginning of Winter. The stem of lettuce grows and expands with the growth of lettuce. Planting too early, too much water in the stem, prone to frost injury. It was planted too late, and the nutrients absorbed in the early stage could not supply the growth of lettuce in winter.

Second, the times and methods of watering. It is enough to water lettuce four times from planting in the first year to harvest in the second year. The first water is poured after planting, and the second water is frozen water. After the frozen water is poured, the border is covered with waste grass mulch, which plays a role of heat preservation and ensures lettuce to survive the winter smoothly. The latter two waters rose in the second year after the Beginning of Spring's temperature rose to about 10 days before harvest.

Third, top dressing. The combination of 60-70 jin high potassium compound fertilizer during each watering is conducive to fruit expansion; second, the use of high nitrogen compound fertilizer to prevent excessive growth of the upper leaves of lettuce, the formation of closed environment, and improve the incidence of diseases.

Fourth, disease prevention. There are few diseases of lettuce. After setting up the arch shed, the lettuce should be released every day to reduce the humidity in the shed and reduce the occurrence of the disease. When the temperature rises, there will be no need for film mulching. In daily management, chlorothalonil or amiceda and mesophytic bacteriocin are sprayed every 10-15 days to prevent diseases.