Nematocides

chemical substances for destroying harmful herbivorous nematodes. The most frequently used nematocides include chloropicrin, methyl bromide, Nemagon, D-D mixture, and carbation. These substances have fumigant properties and cause intoxication of nematodes upon penetrating the body in steam or gaseous form through the respiratory system. Organic phosphorus compounds are also widely used (Carbophos, Metasystox, Fosphamid), which have a contact or systemic effect. Upon contact with the skin, some nematocides permeate the bodies of the worms. Nematocides with systemic action are absorbed by roots or leaves and spread throughout the plant, thus poisoning parasitic nematodes. Some nematocides, such as chloropicrin, simultaneously destroy insects, fungi, and weeds.

Fumigant nematocides are used to control nematodes that parasitize the roots of plants; they are applied to the soil or, before planting, to seeds, bulbs, tubers, or roots. Organic phosphorus nematocides are applied to plants to destroy stem or leaf nematodes. The methods, frequency, and rate for applying nematocides vary considerably and depend on the properties and form of the preparation, the soil and environmental conditions, the species of nematode, and the plant being protected. Nematocides that are toxic to plants are applied between ten and 40 days before sowing or planting or in the fall before the coming year’s crop. Less dangerous nematocides are used at sowing and planting time or on a vegetating crop. Special storage, transport, application, and safety procedures must be followed.