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Related to Defoliants: Chemical defoliants
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



chemical preparations that cause the fall of plant leaves. Ethylene, which—according to several investigators—forms in plants and causes leaves to fall naturally, is a defoliant. Defoliants widely used in agriculture and the rates at which they are consumed (kilograms per hectare of total product) are given in Table 1.

Table 1. Common defoliants
 Rate of consumption (kg/ha)
Magnesium chlorate ...............6–10
Sodium chlorate-pentaborate ...............8–15
Calcium chJorate-chloride ...............6–10
Butifos (S,S,S-tributyltrithiophosphate) ...............0.7–2.0
Merfos (S,S,S-tributyltrithiophosphate) ...............0.7–1.5
Calcium cyanamide ...............40–45
Butindiol-1,4 ...............3–5
Arsenous acid ...............1–3
cis-β-sodium chloracrylate ...............2–10

Butifos and merfos are the most effective defoliants. However, their shortcomings are a disagreeable odor and comparatively high toxicity to vertebrates. Chlorates are effective as defoliants, but they are slower to act. The salts of endoxohexahydrophthalic acid (endothall) and butindiol (butine-2-diol-l,4) are used on a somewhat smaller scale.

Defoliants usually cause 70-85 percent of the leaves to fall; the other leaves shrivel.

Defoliants are widely used to cause the leaves of cotton plants to fall before harvest time.


Mel’nikov, N. N. Khimiia pestitsidov. Moscow, 1968.
Stonov, L. D. Defolianty i desikanty. Moscow, 1961.
Zakirov, T. S. Khimicheskaia defoliatsiia i desikatsiia khlopchatnika. Tashkent, 1968.

N. N. MEL’NIKOV [8–511–1; updated]

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
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This trifecta is what ultimately brought victory to one of the world's poorest nations over one of the world's richest--but it was a victory with a high cost, as the effects of American poisons, defoliants, and the memory of American massacres linger to this day.
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In an effort to deprive the Communist Vietcong guerrillas of the dense cover they found in the hardwood forests and mangroves that fringed the Mekong Delta, the American military sprayed 79,000,000 liters of herbicides and defoliants (including Agent Orange) over about one-seventh of the land area of South Vietnam.