Yvonne A. Thompson, Department of Crop & Soil Science, Pullman, WA, Kimberly A. Garland Campbell, Wheat Genetics, USDA-ARS Washington State University, Pullman, WA and Timothy C. Paulitz, USDA-ARS Washington State University, Pullman, WA
Wheat (Triticum aestivum L.) is one of the world’s staple crops essential to global food security; however its profitable production can be reduced drastically by Fusarium crown rot, caused by a mixture of F. psuedograminearum and F. culmorum. In the US Fusarium crown rot is prevalent in the Pacific Northwest (PNW) states of Idaho, Oregon, and Washington. Cultural, chemical, and biological management practices of this disease are either not effective or not profitable long term. The development of host plant resistance is one of the most effective management methods. Our goal was to identify differential responses to F. culmorum among adapted wheat cultivars and breeding lines. A second goal was to evaluate the screening method for repeatability. Screening experiments were designed to evaluate winter and spring wheat genotypes from the 2013 Washington Variety Trials and Western Regional Trials; a total of five trials. Seeds were planted into conetainers and inoculated as 1-week-old seedlings with a blend of five F.culmorum isolates using the mycelial infested wheat seed method. Each experiment was arranged as a complete block with eight replications and repeating susceptible and moderately resistant checks, and grown in either a growth chamber or greenhouse until Zadoks growth stage 50-60 (early heading). Disease ratings were performed on a 0-10 scale, 0 = no symptoms shown and 10 = lesions and browning present from base of stem nearing second internode. Statistical analysis using mixed linear models showed that these screenings successfully discerned significant differences in responses within nurseries but that repeatability was generally low. Further strategies for increasing repeatability are being explored.