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A plant disease characterized by wilting. Wilting often occurs in the advanced stages of root diseases when water uptake becomes inadequate. However the term is usually applied to diseases in which wilting occurs in the absence of marked root damage. Such wilting may occur either because the vascular tissues are blocked or because water is being withdrawn by parasitic plants, such as witchweeds (Striga) and broomrapes (Orobranche). Blockage of vascular tissues is caused by various fungi and bacteria. It may be due either to the physical presence of vast numbers of microorganisms or to substances, such as gums and tyloses, that the host forms in response to invasion. Examples of wilt diseases are Dutch elm disease, caused by the fungus Ceratocystis ulmi, and wilts of potato, tobacco, and banana, caused by the bacterium Pseudomonas solanacearum.
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