The impact of plant residues on the soybean cyst nematode, Heterodera glycines

The potential of plant residues and plant root exudates, from a range of tr aditional and nontraditional crop species, to protect soybean (Glycine max (L.)) plants against Heterodera glycines (Ichinohe) was examined in vitro a nd under greenhouse conditions. Plant residues from nonhosts Lespedeza capi tata Michx, Lespedeza intermedia (S. Wats.) Britt, Lespedeza hirta (L.) Hor nem, Lolium multiflorum (Lam.), Lolium perenne (L.), Lupinus perennis (L.), Melilotus officinalis (L.) Lam., Medicago sativa (L.), Trifolium pratense (L.), Fairway B Lawngrass mixture, and Pisum sativum (L.) reduced the numbe r of H. glycines juveniles in the soil prior to planting soybeans and subse quently in the roots of soybeans. Root exudates of nonhosts Lespedeza capit ata, Trifolium hybridum (L.), Trifolium repens (L.), Lolium multiflorum, Lu pinus perennis, Echinochloa crusgalli (L.) Beauv., Vicia villosa (Roth), Me dicago sativa, and of the host G. max increased the egg hatching rate of H. glycines in comparison to the water control. In addition, root exudates of Trifolium repens and Lolium multiflorum increased egg hatching by 37.9 and 46.6%, respectively, compared to root exudates of soybeans. Root exudates of Trifolium repens, Lolium multiflorum, E. crusgalli, Lupinus perennis, Tr ifolium hybridum, Medicago sativa, and G. max significantly increased neutr al lipid utilization of H. glycines juveniles in comparison to the control. Overall, Lolium multiflorum was the most effective of all species tested f or reducing populations of H. glycines, by increasing egg hatching: of the nematode in the absence of a host, depleting lipid reserves of the juvenile s, and inducing the lowest nematode parasitism of all nonhost residues stud ied.