Reasons for tomato wilt include inadequate watering, vascular wilt conditions, tomato spotted wilt virus, walnut toxicity and stalk borers. Tomato plants suffering from wilt due to inadequate watering or attack by stalk borers can survive with proper treatment. Tomato plants infected by the other conditions listed above cannot survive.
Tomatoes need 1 inch of water per week to thrive. If a tomato plant receives too little water, its leaves may wilt. Instituting a weekly deep-watering regimen helps to revive the plant. Tomatoes are vulnerable to vascular wilt diseases caused by the invasion of their roots by soil-borne fungi that spread into the plant's stem and block the flow of water to the leaves. This causes the leaves to wilt and the plant to die.
There is no treatment for vascular wilts. Tomato spotted wilt virus is a disease that can infect the plant in the greenhouse or field. Causing wilting and death, wilt cannot be cured.
Black walnut trees produce a toxic material called juglone. This material causes wilting, stunting and death of affected plants. There is no treatment. Stalk borers are caterpillars whose larvae bore into the stalks of tomato plants and cause wilting. Tomato plants can survive infestation by stalk borers with proper care.