The reason and prevention of tomato leaf rolling

Whether in open or protected areas, tomatoes are prone to leaf curling with different symptoms. After many years of observation and summary, the reasons for tomato leaf rolling can be roughly divided into the following six: Virus disease damage: Virus disease can easily lead to curling of tomato plants, and the infected plants are dwarf, and the leaves are curled and clustered. In severe cases, only leaf veins and no mesophyll are involved. Viral diseases are transmitted through the contact of poisonous insects (such as aphids and whiteflies) and sap. High-temperature and dry weather are favorable for their occurrence. Prevention and control measures: (1) Selecting anti-virus strains; (2) Implementing crop rotation to reduce primary infection sources; (3) Spraying 1000 times potassium permanganate solution at the time of onset to prevent diseases such as soft rot and supplementing manganese And potassium. For the control of aphids and other transmission insects, 10% imidacloprid 2000 times or 20% Confodine 4000 times can be used. Hormonal phytotoxicity: The symptoms of 2,4-D phytotoxicity are bent leaves or growing points, new leaves cannot be properly deployed, leaf margins are distorted, stems are raised, and the color becomes lighter. The phytotoxicity symptoms of other hormones such as chlormequat and rhentin are generally lighter than those of 2,4-D. Prevention measures: The hormone concentration for medium-maturing varieties should be 20ppm, the early-maturing variety is 15ppm, and the concentration should be lower when the temperature is high. When using, take care to prevent it from being touched by young leaves or growing points. Never spray it. After the occurrence of phytotoxicity, some chemical fertilizers can be promoted, such as Oppor, natural brassin and so on. Physiological leaf rolling: Before and after the harvest of the tomato, the first ear was slightly rolled, or the entire leaf curled into a tube and became brittle. This is mainly due to high temperature and drought, tomato stomatal closure caused by leaf curling. Preventive measures: Drought-proof exercise before planting until fruit setting. After setting fruit, water and fertilize timely and cover the shade net (cover during sunny day, cover at night, and cover cloudy days). Tea scutellariae damage: Its main symptoms are narrowing of the leaves, stiff erection, shrinkage or distortion, and finally baldness. The control agent can be used 15% fluorenone 3000 times, 1.8% efford 3000 times or 73% gefilte 2000 times. Cold intrusion: Ventilation in the shed is too rapid, and the cold air in the room exchanges strongly with the warm air in the room, which can easily cause curling of tomato leaves near the vent. Under normal circumstances, as long as the air is gradually released, this problem will not arise. Deficiency syndrome: Phosphorus deficiency is characterized by purple backs, brown spots on the leaves, lower leaves rolling up, old leaves turning yellow, dark brown tips dead. In general, the low temperature during seedling stage will affect the absorption of phosphorus, soil acidity or compaction is also easy to lack of phosphorus, can be solved by applying soil phosphate fertilizer or spraying 0.3% potassium dihydrogen phosphate. Magnesium deficiency showed that in the first greenhouse expansion, the old leaves in the lower part of the plant were chlorotic, yellowing appeared between the veins, and then expanded upwards to form yellow variegated leaves. In severe cases, the leaves are stiff or rolled on the edges, and there are necrotic spots or brown bands between veins. Magnesium deficiency in plants can be solved by applying all-element fertilizers or foliar spraying magnesium sulfate 50-100 times.

Posted on October 21, 2018