What are the key points for growing lettuce in summer?
What should be noted when growing lettuce in summer? Please provide guidance. When growing lettuce in summer, pay attention to the following aspects: 1. Pay attention to fertilizer and water management. Because summer temperatures are high, light is strong, ground evaporation is high, and crop transpiration is also high, so at the early stage after planting, water frequently to keep the soil moist. Entering the rainy season in July to August...
What should be noted when growing lettuce in summer? Please provide guidance.
When growing lettuce in summer, pay attention to the following aspects:
1. Pay attention to fertilizer and water management. Because summer temperatures are high, light is strong, ground evaporation is high, and crop transpiration is also high, so at the early stage after planting, water frequently to keep the soil moist. Entering the rainy season in July to August, after each heavy rain, drain water promptly and irrigate with cool water to lower the temperature, so as to protect the leaves. At the later stage of growth, control water appropriately, and do not water for 2 to 3 days before harvest to prevent head splitting. Lettuce has a relatively short growth period, so topdressing is mainly with chemical fertilizers, but attention should be paid to increasing potassium fertilizer to balance nitrogen and potassium, about 15 kg each time.
2. Pay attention to the prevention and control of pests and diseases. The main diseases of summer lettuce are downy mildew, viral disease, and gray mold, as well as sclerotinia rot and leaf spot. Downy mildew can be controlled with 75% chlorothalonil 600 times solution, or 40% enhanced metalaxyl 500 times solution, or 58% metalaxyl-mancozeb 500 times solution; gray mold can be controlled with 50% procymidone, or 50% iprodione 1000 to 1500 times solution, or 50% thiophanate-methyl 500 times solution; for the control of viral disease, in addition to selecting disease-resistant varieties and disease-free good seeds, it should also be combined with the control of aphids, using fenvalerate, menazon, or pirimicarb to promptly control aphids and eliminate transmission. In addition, attention should also be paid to the prevention and control of physiological diseases and nutrient deficiency disorders. For example, boron deficiency in lettuce often causes slow growth of the veins and leaf margins of new leaves, wrinkling and curling of the leaf surface, and uneven leaf color, resembling the symptoms of mosaic virus disease. In severe cases, the leaf tips and leaf margins become scorched, and the growth of the terminal bud is inhibited or dies. Therefore, attention should be paid to the application of boron. Various organic fertilizers contain boron. When necessary, increase the application of borax as a base fertilizer or spray boron fertilizer on the leaves.
3. For summer cultivation, generally do little or no intertillage to prevent increasing the ground temperature. Those not covered with plastic film should mainly focus on surface weeding. At the early stage of growth, generally weed 2 to 3 times. Entering August, when the temperature drops somewhat, the shade shed or shade net can be removed, and the plants enter a natural growth state.
4. In the late stage of lettuce heading, soft rot and head splitting often occur. Soft rot is mainly caused by excessively high temperature inside the head. Therefore, the shade shed should not be removed too early. It is more suitable 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 at the later stage of growth. In addition, to prevent soft rot, it is best not to use human excrement and urine as topdressing.
5. Summer lettuce generally has fewer leaves in the head, so it should be harvested promptly. If harvested late, the head will not only grow larger, but will instead become looser and looser, reducing quality. Harvesting is generally done in the early morning to prevent the leaves from wilting.
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