There are many causes for tomato plants to curl their leaves. Some of the more common reasons for this are sunburn, lack of water, improper fertilizer application, and disease. If you notice your tomato plant leaves curling, look for the cause and take steps to correct it before it spreads.
If your tomato plant’s leaves curl and brown, it is showing signs of sunburn. You should avoid direct sunlight while the leaves are curling or they may be damaged beyond repair.
Watering should also be increased and you may need to switch to a different fertilizer that contains less phosphorus and nitrogen.
If your tomato plant has an open sore on its leaves, remove it immediately and apply a fungicide. If this condition persists, contact your local Master Gardener program for further advice on how to treat the problem.
Early blight can be caused by numerous factors including damp soil, excessive fertilizer application, poor crop rotation, and excess insect damage.
When tomatoes have early blight, the leaves appear misshapen and discolored with irregularly shaped spots appearing along the margins. The spots typically turn brown within a day or two of infection.
The blights develop on new growth rather than on older leaf veins because it begins at the bottom of the plant first before spreading upwards.