Resistance and Tolerance Screening of Spring Wheat Cultivars to Cereal Cyst Nematode (Heterodera avenae) in Southeastern Idaho

Increased populations of Heterodera avenae in southeastern Idaho are associated with increased planting of susceptible cereal cultivars and lack of crop rotation. Identifying high-yield, resistant spring wheat cultivars with tolerance requires testing new genotypes and susceptibility assessments of marketed cultivars. We conducted two experiments to determine whether cultivars with putative resistance could maintain acceptable yield in the presence of H. avenae. We also evaluated the tolerance response in relation to previously tested cultivars. Seven spring wheat cultivars were planted in two irrigated commercial fields that were naturally infested with high populations of H. avenae. Measures of resistance, tolerance, and grain yield were assessed in aldicarb-treated versus nontreated plots. In aldicarb-treated plots in both years, grain yield of the susceptible cultivars Snow Crest, WestBred 936, WB9411, Patwin-515, and WB9668 was significantly increased. The expected yield increase with aldicarb was limited for the moderately susceptible Expresso due to water stress. 'WB-Rockland', carrying the Cre5 resistance gene, maintained its standard yield, while none of the other cultivars in the experiment showed resistance or tolerance. Our results indicated that aldicarb improves wheat grain yield in irrigated crop production systems, and although removed from the market, it is effective and has utility for research. The results also support the hypothesis that high yield susceptible cultivars can mask the effect of H. avenae on grain yield when managed appropriately.