What is rot in plants?

Rot is a plant disease caused by various soil-borne organisms like bacteria, fungi, and fungus-like organisms, leading to plant decomposition and putrefaction. Different types of rot include: * Basal rot: Affects flower and crop bulbs. * Gray mold rot: Impacts vegetables, fruits, flowers, and woody plants. * Heart rot: Common in trees, causing internal decay. * Root rot: Damages plant roots, leading to stunted growth and potential death. * Seed rot: Results in irregular plant stands, especially in wet soils. * Wood rot: Destroys timber, caused by various fungi entering through wounds. Eradication methods involve crop rotation, destroying diseased plants, pruning, disinfection, and heat treatments.

What are some signs that a plant has rot?

Rot in plants, a symptom of fungal disease, manifests in several ways, depending on the type of rot. Some common signs include: * Basal or bulb rot Stunted or yellow leaves that later wilt and die; shoots may fail to emerge. * Gray mold rot Tan to brown soft spots or blotches covered with a dusty mold; seedlings, young shoots, and leaves may wither and collapse. * Heart rot Discolored, lightweight, spongy, crumbly, or powdery heart decay, mainly in trees. * Root rot Plants lose vigor, become stunted and yellow, and may wilt or die back; roots decay and may be covered with mold. * Seed rot Results in row skips and a poor, irregular stand, especially in cold, wet soils. * Wood rot Discolored or stained wood that is lightweight, soft, crumbly or powdery.

What causes rot in plants?

Rot in plants is a disease caused by various soil-borne bacteria , fungi , and fungus-like organisms that leads to plant decomposition and putrefaction. The decay caused by rot can manifest differently, appearing hard, dry, spongy, watery, mushy, or slimy, and it can affect any part of the plant. Common types of rot include basal rot, gray mold rot, heart rot, root rot, seed rot, and wood rot. Factors such as high or low soil moisture can also affect the development and severity of root rot diseases. Wounds from physical injuries can further weaken plants and enable pathogens to enter, leading to rot and additional damage.

What kinds of organisms are responsible for plant rot?

Plant rot is caused by various soil-borne organisms, including bacteria , fungi , and fungus-like organisms called Oomycota . These pathogens lead to plant decomposition, which can manifest differently depending on the specific organism and plant part affected. Some common types of rot and their causes: * Basal rot Various fungi and bacteria * Gray mold rot Botrytis cinerea * Heart rot Various fungi * Root rot Armillaria mellea , Clitocybe tabescens , Fusarium , Pythium , Phytophthora , and Aphanomyces * Seed rot Various fungi and bacteria * Wood rot Daedalea , Fomes , Lenzites , Polyporus , Poria , and Stereum Different control methods are required because the causal agent may induce several different symptoms, even on the same plant organ.

How does rot spread from one plant to another?

Rot spreads from one plant to another through various means, depending on the causal agent, which may be bacteria, fungi, or fungus-like organisms. These pathogens can be transmitted by windblown rain or dust, which carry foliage invaders from one plant to another. Humans can also spread bacteria through activities such as cultivation, grafting, pruning, and transporting diseased plant material. Additionally, animals, including insects and mites, can act as transmission agents. Once a pathogen infects a plant, it may remain dormant on or inside the plant tissue when conditions are unfavorable for growth and multiplication. Fungal diseases, which account for the majority of infectious plant diseases, are controlled through the use of disease-free seeds, crop rotation, and fungicides.

What can gardeners do to prevent or treat rot in plants?

To prevent or treat rot in plants, gardeners can take several steps. It is important to start with disease-free plants and use resistant varieties in well-drained soil with plenty of organic matter. Rotating annuals and biennials, and avoiding root or crown injury can also help. Proper fertilization, watering, pruning, and pest control are essential for maintaining plant health and preventing rot. Eradication methods include crop rotation, destroying diseased plants, eliminating alternate hosts, pruning, disinfection, and heat treatments. Improving drainage can help to avoid root rot . Seedbed drenches of fungicides can also be beneficial for controlling rot in limited areas.

Rot

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Shelf fungus (Polyporus betulinus), which causes decay of birch trees

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Key People:: Lewis Ralph Jones

Related Topics:: seed rot; red rot; root rot; wood rot; soft rot

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Rot

plant disease

Also known as: decay

Written and fact-checked by

Britannica Editors

Last updated

Nov. 4, 2026 •History

Types of rot

Basal rot, also known as bulb rot, is a widespread disease that can infect all flower and crop bulbs and is caused by a variety of fungi and bacteria. Shoots fail to emerge or leaves are stunted and yellow to reddish or purplish; the leaves later wilt and die.

Gray mold rot is caused by fungi in the genus Botrytis, usually B. cinerea. The disease is characterized by soft, tan to brown spots or blotches that become covered with a dusty mold. Gray mold rot can cause seedlings, young shoots, and leaves to wither and collapse and can cause buds, flowers, and fruits to become flecked and rotten. Most vegetables, fruits, flowers, and woody plants are susceptible.

Most trees are susceptible to heart rot, a fungal disease that produces a discoloured, lightweight, spongy, crumbly, or powdery heart decay. Celery and certain root crops are also vulnerable.

Root rot is caused by numerous fungi, especially Armillaria mellea, Clitocybe tabescens, and Fusarium, and many oomycetes, including Pythium, Phytophthora, and Aphanomyces. Plants lose vigour, become stunted and yellow, and may wilt or die back and drop some leaves. They do not respond to fertilizer and water. Trees so affected die gradually; roots decay and may be covered with mold or black stringlike strands called rhizomorphs (Armillaria, Clitocybe). Root rot can be avoided by growing disease-free plants and resistant varieties in well-drained, well-prepared soil with a high content of organic matter; rotating annuals and biennials; avoiding overcrowding and root or crown injury; maintaining vigour by proper fertilization, watering, pruning, and cultivation; and controlling rodents, insects, nematodes, and weeds. Seedbed drenches of fungicides are often beneficial for limited areas of flowers, shrubs, and trees. Soil for use in seedbeds and in pots can be sterilized by heating or by chemical treatment.

Seed rot results in row skips and a poor, irregular stand; it is especially troublesome in cold, wet, heavy soils.

Wood rot destroys economically significant amounts of timber each year. It is caused by hundreds of fungi, including species of Daedalea, Fomes, Lenzites, Polyporus, Poria, and Stereum. Affected wood is often discoloured or stained, lightweight, soft, crumbly, or powdery. Damage usually occurs slowly, often over a period of many years. Infection occurs almost entirely through wounds. Hoof- to shelf-shaped fruiting bodies (conks) develop along the trunk and branches; or mushrooms may form at the trunk base or at the sites of wounds. A fruiting body or mushroom cluster indicates extensive decay. Wood rot can be avoided by removing dead and dying branches, making pruning cuts flush with the stems (leaving no stubs as possible entry for fungi), and wrapping young trees to protect against tree borers that can carry the causal fungi. Tree wound dressings are of doubtful value in preventing rots.