| Excessive heat can cause older tomato leaves to curl. It's nothing to worry about. Curled leaves can have other causes, though. Underwatering is once cause. Or, insects. Look for aphids within curled leaves. Nematodes (microscopic worms) that infest soils and tomato roots can caused stunted plants, malformed leaves, and yellowing. Bacterial canker causes leaf edges to curl upward, turn brown, wither, then die; the whole plant becomes stunted. Curly top, a virus, curls and twists leaves and stunts plants. Thickened, upward rolling, older leaves may be a sign of Psyllid Yellows. If you do not find aphids (a relatively easy-to-cure problem) and the symptoms appear to get worse, it may be time to dispose of the plant and avoid planting in the same hole with another tomato. In the meantime, check for further symptoms of disease, give the plant a good dose of fertilizer, and water deeply once or twice a week. Good luck and good gardening. |
