1, viral disease, viral disease caused by leaf rolling, there are six common types: mosaic, fern leaf type, stripe type, giant bud type, leaf type and yellow type. The infected plants are short, the leaves are curled and clumped, and in severe cases there are only veins and no mesophyll. Viral diseases are transmitted through the contact of poisonous insects (such as aphids, whiteflies) and juices, which are beneficial to high temperature and dry weather. Control measures: 1. Select anti-virus varieties. 2. Implement rotation and reduce the source of initial infection. 3. Spraying 1000 times potassium permanganate aqueous solution at the time of onset can prevent diseases such as soft rot and supplement manganese and potassium. For the control of aphids and other poisonous insects, 10% imidacloprid 2000 times solution or 20% liquid or 20% Kangfudu 4000 times solution can be used.
2, 2.4-D and other hormonal phytotoxicity 2.4-D phytotoxicity symptoms are curved leaves or growth points, new leaves can not be unfolded normally, the leaves are twisted and deformed, the stems are convex, and the color becomes lighter. Other hormones such as chlormequat, anti-fallin and other phytotoxic symptoms are lighter than 2,4-D. Control measures: The concentration of hormones used in medium-maturing varieties should be 20PPM, and the early-maturing varieties should be 15PPM. When the temperature is high, the concentration should be lower. When using it, take care to prevent it from getting on the young leaves or growing points. Never spray it. After the phytotoxicity, some long-term fertilizers, such as Opul, natural brassinolide, can be applied. The area of ​​the phytotoxicity is large, and there is no morbidity center, which is different from other diseases.
3. Physiological leaf rolling, before and after tomato harvesting, the first ear leaves are slightly rolled, or the whole leaves are curled into a tube shape and become brittle. The reason is that due to the high temperature and drought, the tomato pores are closed, causing the leaves to curl. Control measures: carry out drought-resistant exercise after planting and before fruit setting. Watering and fertilizing at the right time after fruit setting, and covered with a shade net. It is covered during the sunny days and exposed at night. It is not covered on cloudy days.
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