Tomato wilt is a disease in tomato plants caused by infectious organisms, environmental conditions, or poor agricultural practices. Plants with this problem will start to develop yellowing, drooping leaves which eventually brown and die off entirely. The entire plant can be involved, or the tomato wilt may be isolated to specific portions. Treatment involves preventative care to keep plants healthy and prompt intervention when they start to show signs of disease. Some forms of tomato wilt can involve infectious organisms that live in the soil, which may mean it will not be possible to plant tomatoes and other nightshades in the same location in the future.
Fungus is a common culprit behind tomato wilt. This includes Fusarium, Verticillium, and southern blight wilt, all of which involve fungal colonization of the plant that makes it difficult for it to get the nutrients it needs. Another cause can be bacterial infection, seen with canker and tomato pitch necrosis. Signs of tomato wilt in these cases can include spotting and curling of the leaves as they slowly die from lack of nutrients and the plant starts to droop.
Pests may be involved as well. Root-rot nematodes can damage the root system of a tomato plant, making it impossible to take up water and nutrients, while stalk borers damage the vascular system in the stalks of the plant. Sometimes a neighboring plant causes tomato wilt; walnuts and butternuts secrete an herbicide designed to eliminate competitors that can kill tomatoes, for example. Tomatoes can also be subject to viral infection, most notably with the Tomato Spotted Wilt Virus (TSWV).
Poor climate conditions can contribute to leaf curl and eventual wilt. These can include unusually high temperatures, drought, or waterlogged soil. Gardeners may cause tomato wilt by not watering plants enough or watering them too much, and problems can also be caused by bad mulching habits or failure to select a good growing location. These plants need well-drained soil because their roots do not like to be wet, and they also require a warm spot shielded from winds.
When tomato wilt starts to develop, it is important to determine why. If infectious organisms are involved, plants should be uprooted and destroyed so the disease cannot spread. Pests may be eliminated with the use of appropriate chemicals or organic approaches, such as companion planting to discourage insects. Gardeners can also consult an agricultural extension or gardening organization to get cultivation tips, which may help them determine if the problem is caused by something they are doing.