Wilt
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What is wilt in plants?
Wilt is a common plant disease symptom where leaves and stems lose water, causing them to droop. This can happen due to various reasons. Nonwoody plants depend on water pressure (turgor) to stay erect, but they constantly lose water through transpiration. When water loss exceeds intake, cells collapse, leading to wilting. Wilting can also result from infections caused by fungi, bacteria, or viruses, collectively known as "wilt" diseases. Examples of specific wilt diseases include Verticillium wilt, Fusarium wilt, Panama disease, and Dutch elm disease. Most plants recover quickly when watered, but prolonged dehydration or untreated infections can be fatal.
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What are the main symptoms of wilt disease?
Wilt is a plant disease symptom where leaves and stems lose rigidity and droop due to water loss. Specific wilt diseases are caused by various pathogens. For example, Verticillium wilt results in leaves turning yellow, wilting, and withering, sometimes stunting growth or causing branch dieback. Bacterial wilt leads to stunting, wilting, and withering, with discolored water-conducting tissue and potential bacterial ooze. Spotted wilt, a viral disease, causes stunted growth, rings and spots on leaves/fruits, distorted leaves, and wilting tops.
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What causes wilt diseases in plants?
Wilt diseases in plants are typically caused by a variety of pathogens, including fungi, bacteria, and viruses. These pathogens disrupt the plant's ability to transport water, leading to a loss of turgidity and subsequent drooping of leaves and stems.
Specific wilt diseases include Bacterial wilt, caused by various bacteria species, induces stunting and withering, and Verticillium wilt, a destructive fungal disease, particularly in cooler climates, affecting numerous plant species.
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How do wilt diseases spread among plants?
Wilt diseases, characterized by water loss in leaves and stems, are caused by various pathogens like fungi, bacteria, and viruses. These pathogens disrupt the plant's vascular system, hindering water and nutrient transport, leading to wilting and potential death.
Fungi, accounting for most infectious plant diseases, spread through spores via wind, water, soil, insects, and infected plant remains. Bacterial wilt spreads through various bacterial species, causing stunting and withering, often evident with a bacterial ooze from cut stems. Viruses, like spotted wilt, are transmitted by insects such as thrips, leading to stunted growth and discolored spots on leaves and fruits.
Control measures include using disease-free seeds, destroying infected plants, crop rotation, and resistant plant varieties.
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What are some examples of plants affected by wilt diseases?
Wilt diseases lead to water loss, causing leaves and stems to droop. These diseases are triggered by various pathogens, such as fungi, bacteria, and viruses.
Examples of plants affected by wilt diseases:
* Fusarium wilt Several hundred plant species are susceptible, including economically important food crops such as sweet potatoes, tomatoes, legumes, melons, and bananas.
* Verticillium wilt Several hundred species of trees, shrubs, vines, flowers, house plants, vegetables, fruits, field crops, and weeds are affected.
* Bacterial wilt Sweet corn, alfalfa, tobacco, tomato, and cucurbits (e.g., squash, pumpkin, and cucumber) are affected.
* Spotted wilt Plants commonly are stunted and bunchy. Brown, purplish, pale green, red, yellow, or white rings (often zoned) and spots form in leaves, flowers, and fruit.3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How can farmers and gardeners prevent or treat wilt in their plants?
To prevent or treat wilt, which is a common plant disease caused by a variety of fungi, bacteria, and viruses, consider these measures:
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Water Management Ensure proper drainage to avoid overwatering, which can lead to root issues and wilt. Most plants recover from wilting when they get enough water, but prolonged dehydration can be fatal.
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Disease-free Plants Grow disease-free and resistant plants. Modern breeders have developed resistant strains and varieties for many important food crops.
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Crop Rotation Practice crop rotation with resistant or immune plants for five years or longer.
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Sanitation Destroy infected plants and susceptible weeds. Sterilize tools between cuts when removing wilted branches.
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Soil Treatment Soil known to harbor Verticillium can be fumigated or heat-treated to kill the disease organisms.
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Fungicides Use appropriate fungicides to control fungal diseases.
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Wilt, common symptom of plant disease resulting from water loss in leaves and stems. Affected parts lose their turgidity and droop. Specific wilt diseases—caused by a variety of fungi, bacteria, and viruses—are easily confused with root and crown rots, stem cankers, insect injuries, drought or excess water, soil compaction, and other noninfectious problems. See also Fusarium wilt; Panama disease; Dutch elm disease.
Bacterial wilt
Bacterial wilt, caused by numerous species of the genera Corynebacterium, Erwinia, Pseudomonas, and Xanthomonas, induces stunting, wilting, and withering, starting usually with younger leaves. Stems, which often shrivel and wither, show discoloured water-conducting tissue. A bacterial ooze is often evident when infected stems are cut and squeezed. Rapidly expanding, dark green, water-soaked areas or streaks may develop first in leaves.
Bacterial wilt may be managed by growing resistant varieties; planting disease-free materials in well-drained, fertile soil that is clean or sterilized; observing stringent sanitation including weed- and insect-control measures; and rotating susceptible crops.
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Oak wilt
Oak wilt, caused by the fungus Ceratocystis fagacearum, is a serious disease in the eastern half of the United States. All oaks (Quercus) are susceptible, as are Chinese, European, and American chestnuts (Castanea) and tan oak (Lithocarpus densiflorus). Trees in the red oak group usually die within several weeks during late spring and summer. Their leaves turn pale or dull green, look water-soaked, curl upward, and often become yellowed or bronzed from the margins inward; the upper branches are usually affected first. White oaks commonly die back slowly over several years. Their leaves usually wilt, turn light brown, curl, and cling to their stems. The disease is spread from tree to tree by natural underground root grafts, sap- and fungus-feeding insects, and possibly by squirrels.
Control measures include prompt removal of diseased trees, injecting fungicide into the soil midway between healthy and recently infected trees, avoidance of injuring or pruning of trees from budbreak to midsummer, and painting wounds promptly with tree wound dressing.
Spotted wilt
Spotted wilt, caused by a virus, is transmitted by the larvae of several species of insect called thrips. Plants commonly are stunted and bunchy. Brown, purplish, pale green, red, yellow, or white rings (often zoned) and spots form in leaves, flowers, and fruit. Long streaks may develop in petioles and stems. Leaves are distorted, sometimes mottled, and may turn yellow or bronze. Tops may wilt and wither; fruit is often rough and distorted. Control includes growing resistant varieties and disease-free stock, spraying or dusting during thrips infestations, promptly destroying infected plants and crop debris after harvest, and observing stringent weed control.
Verticillium wilt
Verticillium wilt is a very destructive fungal disease in cool climates. It affects several hundred species of trees, shrubs, vines, flowers, house plants, vegetables, fruits, field crops, and weeds. The causal agent is the soil-inhabiting ascomycete fungus Verticillium albo-atrum and the related V. dahliae. In hot weather the leaves on one or more branches turn dull green to yellow, wilt, and wither, often from the base upward. Annuals and young trees are often stunted and usually die. Perennials may die branch by branch over a period of from several weeks to years or apparently recover. The sapwood (just beneath the bark) of wilted branches, when cut lengthwise, usually shows dark streaks. Infections occur through roots and wounds.
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Control can be obtained by growing disease-free and resistant or immune plants, rotating with highly resistant or immune plants for five years or longer, destroying infected plants and susceptible weeds, fertilizing and watering to encourage vigour, removing wilted branches on trees and shrubs (sterilizing tools between cuts), and avoiding the wounding of roots or stems when planting or cultivating. Soil known to harbour Verticillium can be fumigated or heat-treated to kill the disease organisms.