Abstract:
Abstract
Plant-parasitic nematodes (PPNs) are obligate parasites that feed mainly on plant roots with common aboveground symptoms of stunting, yellowing, wilting, yield losses, and belowground root malformation due to direct feeding damage. Nematodes are unsegmented, bilaterally symmetric roundworms, usually microscopic, and taper toward both head and tail, but females of some of the species may be pear, lemon, or kidney-shaped. Feeding of many PPNs creates entryways into plant roots for secondary pathogens, while feeding of some species directly transmits plant viruses. Nematodes of greatest importance in organic crops appear to be sedentary endoparasites in the family Heteroderidae including the cyst nematodes (e.g., species of Heterodera and Globodera) and root-knot nematodes (Meloidogyne spp.), and migratory endoparasites of family Pratylenchidae (Pratylenchus spp.). Cyst nematode species including soybean cyst, potato cyst, and cereal cyst nematodes cause huge crop losses.
