Wilt Diseases
Wilt Diseases  Wilt diseases are caused by a common and wide group of the species Fusarium and Verticilium fungi with similar symptoms. The only reliable method for separating these diseases is laboratory culture and identification of the fungus isolated from diseased plants.Damage is usually caused by a blockage of the water conducting tissues of the stem, starving the leaves of water. The disease may persist in the soil for several years depending on the causal organism, and can enter plants through wounds. Some wilts, such as China asters and peas are host specific, while others will attack a wide range of edible and ornamental plants. Susceptible Plants- Fruit, vegetables, especially legumes, tomato, cucurbits, ornamentals, and broad leaf plants are all venerable to wilt diseases.. Symptoms- Plants first show wilting that often starts on lower leaves, with some recovery at night, initially. A dark discoloration can be seen in the middle of the stem when cut well above the soil. The wilt fungi have different general characteristics which will aid in identification and control. These are: · Verticillium thrives in alkaline soil whereas Fusarium grows best in acid soils. · Fusarium is more prevalent in sandy soil; Verticillium in heavy soils. · Fusarium causes more injury when root-knot, reniform or sting nematodes injure the roots; Verticillium does not require injury for infection. · Fusarium can be transmitted internally in seed while Verticillium is not. · Verticillium prefers cooler soil than Fusarium. Prevention and Control- Mound soil around infected plants. If infection is severe, remove all infected plants and associated soil. Do not compost any of the infected plant material. Do not grow susceptible plants on the same site for at least 6 years. Control of wilt diseases is difficult. Carefully follow suggested cultural practices. Crop rotation with tolerant plants and clean tillage to destroy infected tissue will help control wilt diseases. Also see Clematis wilt and Peony blight.
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