Key Field Management Techniques for Head Lettuce in Summer
First of all, pay attention to fertilizer and water management. Because summer temperatures are high, light is intense, ground evaporation is great, and crop transpiration is also high, frequent watering is needed in the early stage after transplanting to keep the soil moist. Entering the rainy season of July to August, after each heavy rain, drainage should be carried out promptly and cool water should be applied to lower the temperature, so as to protect the leaves. In the later stage of growth, water should be properly controlled, ...
First of all, pay attention to fertilizer and water management. Because summer temperatures are high, light is intense, ground evaporation is great, and crop transpiration is also high, frequent watering is needed in the early stage after transplanting to keep the soil moist. Entering the rainy season of July to August, after each heavy rain, drainage should be carried out promptly and cool water should be applied to lower the temperature, so as to protect the leaves. In the later stage of growth, water should be properly controlled, and no watering should be done 2 to 3 days before harvest to prevent head splitting. Its growing period is relatively short, so topdressing should be mainly chemical fertilizer, but attention should be paid to increasing potassium fertilizer to balance nitrogen and potassium, about 15 kg each time.
Second, pay attention to the prevention and control of pests and diseases. In summer, the diseases of lettuce are mainly downy mildew and gray mold, as well as sclerotinia rot and leaf spot. Downy mildew can be controlled by spraying 75% chlorothalonil 600-fold solution or 40% enhanced ridomil 500-fold solution; gray mold can be controlled by spraying 50% sec-ku-mie or 50% iprodione 1000 to 1500-fold solution.
In the late stage of head formation in lettuce, soft rot and head splitting often occur. Soft rot is mainly caused by excessively high temperature inside the head, so the shade shed should not be removed too early; it is more appropriate to remove the shade shed when the daily average temperature falls below 20°C. Head splitting is mainly caused by excessive soil moisture, so watering should be controlled in the later stage of growth.
For summer cultivation, generally little or no intertillage should be done to prevent increasing soil temperature. Where plastic film is not used as mulch, the main task should be surface weeding. In the early stage of growth, generally 2 to 3 weedings should be done. Entering August, when the temperature drops somewhat, the shade shed or shade net can be removed, and the plants enter a natural growth state.