Tomato leaves curl mainly due to environmental stress as a physiological response. Common causes include:
- Excessive heat and drought stress: Tomato plants curl their leaves upward to reduce water loss during high temperatures and dry conditions.
- Watering issues: Both overwatering causing root rot and underwatering can lead to leaf curling.
- Nutrient imbalance: Too much nitrogen or lack of potassium and phosphorus in soil can cause leaves to curl and discolor.
- Pests: Aphids, thrips, whiteflies, and spider mites feeding on the leaves may cause curling.
- Herbicide damage: Drift or soil contamination from herbicides leads to twisted, curling leaves.
- Viral infections: Some viruses like tomato yellow leaf curl virus cause curling along with other symptoms.
Generally, curling is the plant's survival mechanism to conserve water and reduce leaf damage. Addressing watering practices, protecting from extreme heat, managing nutrients, controlling pests, and avoiding herbicide exposure can help prevent or fix leaf curl problems.
