What causes tomato leaf curling? What is missing from tomato leaf curling?

Many times when we grow tomatoes, we find that the leaves of tomatoes are curled. So what is the reason at this time?

Leaf curl caused by virus diseases

Symptoms: Viral diseases are generally spread by aphids, whiteflies and other virus-transmitting insects. Infected plants are short, with curled and clumped leaves. In severe cases, only veins remain on the leaves without mesophyll. Prevention and control measures: In addition to selecting disease-resistant varieties and implementing crop rotation, spray 1000 times potassium permanganate solution in the early stage of the disease, which can cure viral diseases and soft rot diseases. You can also add 100 grams of Virus A (K), 50 grams of Green Fenwei and 25-30 grams of Yibianjing to 50 kg of clean water to make a mixed solution for spraying and control. Spray once every 6-7 days, and spray 2-3 times in a row.

Leaf curling caused by hormone damage

Symptoms: When hormones such as 2,4-D and chlormequat are used excessively or at too high a concentration, the tomato leaves or growth points will bend, new leaves will not unfold normally, the leaf margins will be twisted and deformed, the stems and vines will bulge, and the color will become lighter. Prevention and control measures: Natural brassinolide can be used at a 3000-fold solution for prevention and control.

Physiological leaf curling

Symptoms: Before and after tomato harvest, the leaves of the first fruit curl slightly, or the leaves of the whole plant curl into a tube and become brittle. This is mainly due to high temperature and drought, which causes the stomata of tomato leaves to close. Prevention and control measures: Drought resistance training should be carried out after the plants are planted and before fruit setting. After fruit setting, water and fertilize in time, and cover the plants with shade nets, covering them during the day and uncovering them at night, and not covering them on cloudy days.

Leaf curling caused by tea leaf mites

Symptoms: Leaves become narrow, stiff and upright, wrinkled or twisted, and finally bald. Control measures: Spray 1.8% Aifudin 3000 times or 20% Mitosil 2000 times, once every 6-7 days, and spray 2-3 times in a row.

Leaf curl caused by nutrient deficiency

Phosphorus deficiency: The back of the leaves of the diseased plants are purple-red, small brown spots appear on the leaves, the lower leaves curl up, the old leaves turn yellow, and the leaf tips turn black-brown and die. Generally, low temperatures during the seedling stage of tomatoes will affect the absorption of phosphorus, and acidic or sticky soils can easily lead to phosphorus deficiency in plants. Prevention and control measures: Increase the application of phosphorus fertilizers and spray 0.3% potassium dihydrogen phosphate.

Magnesium deficiency: During the first inflorescence expansion period, the old leaves at the bottom of the diseased plants lose their green color, and yellowing occurs between the veins, which then spreads upward to form yellowed leaf spots. In severe cases, the leaves become stiff or the leaf edges curl up. Prevention and control measures: Apply more nitrogen, phosphorus, and potassium fertilizers or spray 50-100 times diluted magnesium sulfate on the leaves.