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fungicide (fŭnˈjəsīdˌ, fŭngˈgə–), any substance used to destroy fungi. Some fungi are extremely damaging to crops (see diseases of plants), and others cause diseases in humans and other animals (see fungal infection).

Surface fungicides, which keep harmful fungi from penetrating the tissues of a plant, include inorganic and organic compounds. Sulfur compounds, long used on plants, have been supplemented for some time by other chemicals, especially by compounds of copper, such as Bordeaux mixture. After 1945, organic salts of iron, zinc, and mercury were synthesized as fungicides. Most post-1965 fungicides are systemic, acting directly on fungal cells. Antifungal drugs, such as miconazole and terbinafine, are used for human fungal infections.

Plant fungicides are usually applied by spraying or dusting, but some types are applied to seeds and soil for the destruction of vegetative spores. Fungicides used on wood, including creosote, prevent dry rot, and certain compounds are used to make fabrics resistant to mildews. Most agricultural fungicides are preventive; those applied after infection are called eradicant, or contact, fungicides.

In the United States, fungicides are governed by the 1972 federal Environmental Protection and Control Act. They must be registered with the Environmental Protection Agency and must conform to specifications. They must control the disease without injuring the plant and must leave no poisonous residue on edible crops. Antifungal drugs are approved by the Food and Drug Administration.

See also pesticide.

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Substance that kills fungi, including mold and mildew, and yeasts.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in agriculture, any one of several chemical substances capable of completely (fungicides proper) or partially (fungistats) suppressing the development of disease-causing fungi in crops; one of the groups of pesticides.

Fungicides may be classified as inorganic or organic, depending on their chemical composition. Inorganic fungicides include compounds of sulfur (lime-sulfur solution, sulfur powder, sulfur colloid), copper (copper sulfate, copper oxychloride), and mercury

Table 1. Principal organic fungicides used in the USSR
PreparationChemical nameLD50 (mg per kg body weight)FormPurpose
Vitavax ...............5,6-dihidro-2-methyl-1,4-oxathiin-3-carboxanilide3,20075% wetting powderTo combat smut and Rhizoctonia disease in grain crops
Granozan ...............Ethylmercuric chloride26.41.8–2.3% powderTo treat seeds of grain crops, flax, sugar beets, against smut, fusarium wilt, anthracnoses
4,6-dinitro-o-cresol (DNOC) ...............Sodium or ammonium salt of 2-methyl-4,6-dinitrophenol5040% water-soluble powderTo combat a complex of diseases affecting fruit and berry crops
Captan ...............N-trichlorome-thylthio-3a,4,7,7a-tetrahydrophthalimide9,000–15,0000.25–0.6% suspensionTo treat apple and pear trees against scab
Karathane ...............2,4-dinitro-6-(2-octyl)-phenyl crotonate98025% wetting powderEffective against powdery mildew on fruit and berry crops and cucumbers
Zineb ...............Zinc ethylenebis (dithiocarbamate)5,200Slightly watersoluble powderEffective against downy mildew of grapes, late blight of potato, southern blight of tomato

(mercuric chloride, or corrosive sublimate). Organic fungicides (see Table 1) constitute a larger group; they include carbamic acid derivatives (zineb, kuprosin-1, poiimartsin, polikarbatsin), phthalimides (captan, ftalan), quiñones (Phygon), dinitroalkal-phenol esters (Karathane), organomercury compounds (granozan, Mercurohexane), oxathiin compounds (Vitavax), and benzimidazole-based preparations (benomyl). Depending on their effect on the causative agent, fungicides may be classified as protectants or eradicants. Protectants prevent contamination of the plant or stop the development and spread of the causative agent at the site of infection before contamination can occur, primarily by acting on the fungus’s reproductive organs; the majority of fungicides are of this type. Eradicants act on the mycelium, reproductive organs, and wintering forms of the causative agent, which is destroyed after contamination of the plant.

Fungicides are used in various ways: as seed-treating materials to combat diseases in which the causative agents are propagated with seeds or are found in the soil; as soil-treatment preparations that destroy soil-borne causative agents (particularly effective in hotbeds and greenhouses); as preparations for the treatment of plants during dormancy, when they destroy the wintering forms of the causative agent (used in early spring before blossoming, in late autumn, and in winter); as preparations for treatment during the vegetation period (mainly preparations with a protective effect, applied in summer); and as preparations for spraying and fumigating storehouses, especially granaries and vegetable cellars.

Fungicides may be either contact (local) or systemic, depending on their distribution within the plant tissue. During treatment, contact fungicides remain on the surface and destroy the causative agent upon contact. Some have a local, subsurface effect; for example, they may penetrate the hull of the seed. The effectiveness of contact fungicides depends on the length of action, the rate of application of fungicide, surface contactness, photochemical and chemical stability, and weather conditions. Contact fungicides have been used in agriculture since the late 19th century. Systemic fungicides (therapeutants) penetrate the plant tissues, circulate through the vascular system, and suppress development of the causative agent by direct action or by means of metabolism in the plant. Their effectiveness is primarily determined by how rapidly they penetrate and, to a lesser degree, by meteorological conditions. Systemic fungicides came into use in the 1960’s, much later than contact fungicides. The division of fungicides into groups is arbitrary. For example, large doses or higher concentrations of preventive preparations may have a curative effect; thus, seed-treating materials may also destroy causative agents of disease in the soil.

There are various mechanisms involved in the action of fungicides on causative agents. For example, in the treatment of diseased plants with copper sulfate, the copper penetrates the mycelium or spores of the fungus and causes the coagulation of protoplasm; 4,6-dinitro-o-cresol dissociates the processes of respiratory phosphorylation, and zineb blocks enzyme activity. The spectrum of fungicidal activity also varies and depends mainly on the ability of the causative agent to absorb one or another preparation. Some fungicides, such as organomercury preparations and carbamic acid derivatives, suppress the causative agents of many plant diseases; others have a limited spectrum of activity (for example, Vitavax is toxic principally to Basidiomycetes, which cause smut and Rhizoctonia disease), and still others exhibit exclusive specificity (hexachlorobenzene, used against covered wheat smut, and copper preparations, used against downy mildew).

Application methods for fungicides include spraying and dusting of plants and soil, seed treatment, and fumigation of seeds and storehouses. The fungicides may be prepared as dusts, emulsions, suspensions, wetting powders, or aerosols. Systematic use may reduce the effectiveness of some fungicides, owing to the formation of resistant strains of fungi. This can be prevented by strictly observing the proper rates of application and by alternating fungicides. Fungicide production is constantly increasing as a result of the great importance of fungicides to agriculture.

The toxicity of fungicides for plant organisms depends on the chemical nature and concentration or dose of the preparation, the age of the plants, the anatomy and morphology of the plant tissues, the plant’s metabolic characteristics, weather conditions, and other factors. The treatment of vegetating plants with 4,6-dinitro-o-cresol or a nitrafenol, application of which is permitted only during dormancy, substantially lowers yield. Doses or concentrations of such fungicides as butyric solutions of Meta-fos or ftalan in excess of recommended amounts may induce burns and tissue necrosis. Some fungicides, such as hexachlorane derivatives, can contaminate plants and their products and impart a specific unpleasant odor and taste. Small doses of certain fungicides stimulate plant development.

Most fungicides are slightly toxic to warm-blooded animals and man; the lethal dose 50 ranges from 500 to 11,000 mg per kg of body weight. Work with fungicides is governed by safety rules, and the use of individual safety devices, such as protective clothing, protective footwear, and respirators, is mandatory. Most fungicides are not hazardous or only slightly hazardous to insects, such as bees. Certain fungicides, for example, organochlorine compounds, have a high stability in biological media and decompose slowly, which creates a danger of their accumulation, including in plants and plant products; permissible residual quantités are usually 0.05–2 mg per kg of product. Some fungicides affect all living organism they contact and may prove harmful to useful microorganisms, insects, birds, and fish; systematic application may lead to the disturbance of biological equilibrium in biocenoses.

In order to avoid the adverse effect of fungicides on the environment, strict observance of the instructions for fungicide use is essential, especially with respect to doses and periods of treatment. In many countries, including the USSR, the use of fungicides is controlled by law.


Khimicheskaia zashchita rastenii. Edited by G. S. Gruzdev. Moscow, 1974.
Sistemnye fungitsidy. Moscow, 1975. (Translated from English.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


An agent that kills or destroys fungi.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


A substance that is poisonous to fungi; retards or prevents the growth of fungi.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


a substance or agent that destroys or is capable of destroying fungi
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Fungistatic activity was defined by CFU reductions < 3-logs from the starting inoculum, and fungicidal activity was defined by CFU reductions [greater than or equal to] 3-logs (denoted by dashed lines in Figures 1-5).
We assessed the viable cell count over time to verify the fungicidal or fungistatic activity of the test product and to evaluate the interaction of the test product with the microorganism, in order to characterize the dynamic relationship between the product concentration and length of exposure [40].
(3) Terbinafine is considered fungicidal rather than fungistatic.
The fungicidal activities of the series of title compounds 6 were tested at 50 g/ml by modified method described in the literature [29].
MOB-015 is a new topical treatment for nail fungus (onychomycosis) with fungicidal, keratolytic and emollient properties.
Yard Guard is also formulated to control fungi such as mildew within plant life as it contains fungicidal properties which help control most fungal organisms.
These studies were targeted to evaluate the potential of pre and postharvest fungicidal applications and on-tree foliar spray of a plant activator viz.
MOB-015 is based on Moberg Derma's patent-pending formulation technology that facilitates the transportation of high concentrations of a fungicidal substance in and through nail tissue.
By the middle of the nineteenth century, sulfur had gained a lot of popularity for its fungicidal properties, and its use as a fungicide gradually increased until the fungicidal properties of Bordeaux mixture [4] in the control of mildew of grapes were discovered.
Before the weekend, stock up at your local DIY store on decking treatment, methylated spirits, fungicidal wash, a stiff broom, protective gloves and goggles, and a good quality wood-stain brush.
From familiar fungicidal and bactericidal peptides the research scientists produced sequence variations and tested them in vitro on various microbes.