Figure 1.

Nematode infections on plant roots. (Left) Root-knot galls caused by a member of the nematode genus Meloidogyne on plant roots. (Center) Microscopic view of a root-knot nematode (Meloidogyne sp.) female feeding on plant giant cells. Members of this group cause large galls as well as malformed and stunted roots and above-ground plant parts (photo courtesy of E. Bernard, University of Tennessee, Knoxville, TN). (Right) Cyst nematode (Heterodera avenae) females on oat roots. Note the swollen bodies. This nematode is closely related to those studied by Smant et al. (2). The females mature into egg-filled cysts and greatly reduce plant growth, development, and agricultural yield (photo courtesy of R. Cook, Institute of Grassland and Environmental Research, Aberystwyth, U.K.).