MANAGEMENT OF LESION AND DAGGER NEMATODES WITH ROTATION CROPS
Annual rotation green manure crops of selected brassicas, buckwheat, forage pearl millet, forage radish, black-eyed Susan, sesame, sudangrass, and velvetbean were evaluated to determine impacts on lesion nematode Pratylenchus penetrans and dagger nematode Xiphinema americanum populations densities. Canadian forage pearl millet ‘101’and ‘Tifgrain 102’ millet effectively controlled P. penetrans but increased population densities of X. americanum. Black-eyed Susan (Rudbeckia hirta) and sudangrass ‘Trudan 8’ also reduced P. penetrans densites but not X. americanum. Rapeseed and other brassicas as a green manure reduced X. americanum densities but did not suppress P. penetrans. Brassica juncea ‘Pacific Gold’, B. napus ‘Dwarf Essex’, but not mustard ‘Caliente’ resulted in low densities of X. americanum in soil. Velvetbean and sesame increased both P. penetrans and X. americanum population densities. A moderately suitable host plant such as buckwheat was ineffective in managing both P. penetrans and X. americanum populations. These results emphasize that suppressive effects of any given cover crop are nematode-specific, and that within a group of cover crops, e.g., the Brassicaceae, species and varieties can vary substantially in their effectiveness. If the rotation crop chosen is a good host for the nematodes present, it may exacerbate the problem instead of controlling it.