Assessment and Management of Root Lesion Nematodes in Montana Wheat Production

Root lesion nematodes (Pratylenchus spp.) hinder dryland wheat production worldwide. Montana, a leading U.S. wheat production region, has climatic conditions favorable for Pratylenchus spp. A 2006-2007 statewide soil survey revealed damaging populations of Pratylenchus neglectus, primarily in winter wheat production areas of Montana, whereas P. thornei was not found. Analyses of wheat yields in infested fields revealed negative correlations between yields and spring nematode populations (all P < 0.05 and all R² > 0.2). Statewide yield losses due to root lesion nematodes were an estimated 12 and 15% for winter wheat in 2006 and 2007, respectively. A subsequent study conducted in 2008 to 2009 revealed significant differences in reproductive success of P. neglectus among seven rotation treatments (P < 0.001). Nematode populations persisted from spring to fall under fallow, barley, pea, and camelina; increased under winter wheat and canola; and decreased under lentil. Populations were sustained through winter following winter wheat and barley but declined following canola, camelina, pea, lentil, and fallow. A screening of 19 barley lines for resistance to P. neglectus revealed significant variation in resistance among entries (P < 0.001), with 'Harrington' barley displaying promising levels of resistance. Development of resistant wheat cultivars remains a principal goal in managing this nematode.