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POSTERS: Host resistance screening

Idaho spring wheat varies in susceptibility to Fusarium head blight
Suzette Arcibal - University of Idaho. Juliet Marshall- University of Idaho

Fusarium head blight (FHB) is an emerging disease of small grains in the Pacific Northwest (PNW) due to increasing corn acreage and prevalence of Fusarium graminearum. The use of resistant varieties reduces both FHB and deoxynivalenol (DON) contamination. However, varieties with specific end-use quality characteristics tend to be susceptible to FHB and have higher levels of DON. To facilitate wheat variety improvement, screening nurseries comprised of widely-grown cultivars and advanced breeding lines were established at Aberdeen, ID in early May of 2017 and 2018. Corn inoculum was applied at a rate of approximately 30 g/m2 three weeks before anthesis of the earliest maturing variety. Plot severity and FHB incidence were evaluated at soft dough while DON were determined from harvested grain samples. FHB index (IND) values were calculated for the 37 entries that were evaluatedfor both years. Under high disease pressure in 2017, significant varietal responses ranged from 1.4 to 49.9% for IND and from 0.4 to 28.1 ppm for DON. Under moderate FHB pressure in 2018, IND values similarly ranged from 0.2 to 52.9% but the range of DON concentration of 0.3 to 19.5 ppm was significantly less. Low correlation (r) between arc-transformed IND (arcIND) and log-transformed DON (logDON) of 0.3 and 0.4 in 2017 and 2018, respectively, confirms that breeding efforts must target both FHB symptom development and DON accumulation. Disease variables will be analyzed with weather data to develop FHB prediction models specific to the arid, irrigated production areas in Idaho and other PNW states.