Nematode-wild plant interactions and their implication in nematode management

Many species of plant parasitic nematodes are known to have hundreds of host plant species, both cultivated and wild. In the absence of host crop plants, wild plants often are good alternative hosts for the nematodes of which they not only ensure survival but also soil population densities larger than the tolerance levels for different host crop plants. This is known to occur for a few cyst nematodes, such as the sugar beet cyst nematode, Heterodera schachtii, in the presence of several crucifers and chenopodiaceous wild plants, and for many other nematodes known to have rather large host ranges. These include the bulb and stem nematode, Ditylenchus dipsaci, the root-knot nematodes, Meloidogyne spp., and the lesion nematodes, Pratylenchus spp., which have as host plants many wild plants infesting crops during a period of the year suitable for the nematodes. The control of infesting weeds not only improves the growth of the cultivated host plants because of absence of competitors, but also prevents increase of soil nematode densities in their absence and, therefore, may serve as an effective and useful control option of nematodes, especially suggested for inclusion in integrated pest management programmes based on control methods alternative to synthetic nematicides.