Root-Knot Nematodes

a broad group of parasitic worms of the class Nematoda which cause galls on plant roots.

Root-knot nematodes are divided into four families that include five genera: Meloidogyne, Nacobbus, Hemicycliophora, Xiphinema, and Longidorus. The genus Meloidogyne contains more than 30 species, of which four are found in the USSR as well as throughout the world; they are M. hapla (earlier called M. marionï), M. incognita, M. arenaria, and M. javanica. The males are wormlike, reaching up to 2 mm; the females are puffed up and jug-shaped, with a length of about 1 mm. Root-knot nematodes are polyphagous, attacking more than 2,000 plant species (including vegetables and industrial plants, decorative and herbaceous plants, trees and bushes). Their development takes 19–45 days. A female inside a gall will lay as many as 2,000 eggs in her lifetime. As it develops in the egg, the larva of the nematode goes through its first molt, then emerges and embeds itself in the root, feeding voraciously on the juices of the host plant. Then it becomes either an immobile female or a mobile male that leaves the gall in search of a female.

Countermeasures include planting healthy material, crop rotation using crops that are resistant to root-knot nematodes, and treatment of the soil with chloropicrin, Nemagon, or Carbation.