Velvetbean and bahiagrass as rotation crops for management of Meloidogyne spp. and Heterodera glycines in soybean

Soybean (Glycine max) yield often is limited by the phytoparasitic nematodes Meloidogyne spp. and Heterodera glycines in the southeastern United States. We studied the effects of rotation with bahiagrass (Paspalum notatum), velvetbean (Mucuna pruiens), or continuous soybean, aldicarb, and soybean cultivar on yield and population densities in two fields infested with a mixture of Meloidogyne spp. and H. glycines. Velvetbean and bahiagrass reduced population levels of both nematode species to near zero prior to planting soybean. At harvest, both nematode populations were equal in soybean following bahiagrass and continuous soybean but were lower following velvetbean. Both bahiagrass and velvetbean as previous crops were equal in producing significantly (P < 0.003) higher yield than continuous soybean. Velvetbean increased subsequent soybean yield by 98% and bahiagrass increased subsequent soybean yield by 85% as previous crops compared to continuous soybean. The major differences between the two rotation crops were yield response of the nematode-susceptible cultivars and at-harvest nematode populations. Velvetbean tended to mask genetic differences among cultivars more so than bahiagrass. Velvetbean also produced a more longterm effect on nematode populations, with numbers of both Meloidogyne spp. and H. glycines lower in soybean following velvetbean than following bahiagrass or continuous soybean.