Viral infections and wind damage contribute to tomato leaves curling, reports Gardening Know How. Physiological conditions including extreme temperatures cause tomato leaves to curl up. Although the exact cause of this condition is unknown, it is believed to be a form of self defense.Continue Reading
Sometimes only the new leaf growth shows signs of curling while the old leaf growth appears to be normal, Gardening Know How states. High winds are capable of damaging leaves and stems on a tomato plant. Viral infections, which infect tomato plants and cause leaves to curl, are transmitted by whiteflies and infected transplants of plants. This condition takes up to three weeks to become visible. Left untreated, plant growth becomes stunted, flowers drop off and fruit production is significantly reduced. Destroying these plants is the best option. This prevents further transmission to nearby tomato plants.
Leaf roll, the self-defensive curling of the leaves, results from physiological variables, Gardening Know How states. During excessively cool and moist conditions, leaves roll in an effort to repel the excess moisture. Uneven watering, high temperatures and dry spells also cause leaves to curl upward to conserve moisture. Plum and paste varieties are more susceptible to this condition. Leaf curl caused by physiological variables does not affect the overall growth or crop yield.Learn more about Outdoor Plants & Flowers