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a toxic substance used in the gaseous or vapor state to destroy harmful insects and causative agents of plant diseases. Fumigants constitute a class of pesticides.
One of the most commonly used fumigants is methyl bromide, which is used to kill soil-borne insects and agricultural pests (rate of application, 26–60 g/m3; permissible vapor concentration in a work area, 1 mg/cm3). Other common fumigants include 1,2-dichloroethane, which is employed for soil fumigation against insects of the Phylloxeridae family (800–1,200 kg per hectare [ha]); Nemagon, which is used for fumigation against soil insects (200–300 kg/ha); and D-D Mixture, which is a preparation consisting of dichloropropanes (500–1,000 liters/ha) and is also used for soil fumigation. Hydrocyanic acid, another widely used fumi-gant, is prepared in gaseous form at the fumigation site from such salts as sodium cyanide and tsianplav (a mixture of calcium cyanide and sodium cyanide); it is used to control populations of susliks (120–150 g/ha) and to fumigate tea bushes, citrus trees (under tents), planting stock, and mills, including groats mills (100–125 g/m3). Flies and other flying insects in closed areas are destroyed with aerosol insecticides.
Gas masks and other protective devices are used when working with fumigants. Since many fumigants are explosive and flammable, some of them—such as dichloroethane and carbon disulfide—are mixed with fire-extinguishing chemicals; for example, carbon tetrachloride is added to dichloroethane. Moreover, possible sources of combustion and explosion are removed; electric welding, the striking of matches, and the lighting of fires are forbidden in the area being fumigated. Rubber hoses are used for decanting flammable liquids.
REFERENCESMel’nikov, N. N. Khimiia i tekhnologiia pestitsidov. Moscow, 1974.
Spravochnik po pestitsidam. Edited by L. I. Medved’. Kiev, 1974.
E. I. ANDREEVA