Detection of Dual Heterodera avenae Resistance plus Tolerance Traits in Spring Wheat

The cereal cyst nematode Heterodera avenae reduces wheat yield in the Pacific Northwest. Resistance and tolerance traits among spring wheat cultivars were poorly defined. Screening trials were conducted with 39 cultivars over a 2-year period in irrigated commercial fields that were infested by H. avenae. Comparisons were made between drill strips treated or untreated with aldicarb at the time of planting. Root sampling at the time of plant anthesis indicated that cultivars differed greatly in susceptibility to H. avenae, with numbers of newly produced white H. avenae females ranging from <5 to 70 per plant. Aldicarb reduced mean numbers of white females as much as 99% on the most susceptible cultivar (`Glee') and increased mean grain yield as much as 77% for the least tolerant cultivar (Vataldo'). Density of H. avenae eggs in untreated soil following harvest was significantly higher than the density in aldicarb-treated plots. Agronomically acceptable traits of resistance plus tolerance were identified in one cultivar of hard red spring wheat ('WB-Rockland') and two cultivars of hard white spring wheat ('Klasic' and 'LCS Star') but in none of the soft white spring wheat cultivars. This is the first report of spring wheat cultivars expressing the dual traits of resistance plus tolerance to H. avenae.