Assessment of malting barley varieties for resistance to important barley diseases in New York

In 2013, the State of New York created the Farm Brewery License that requires brewers who benefit from the tax and marketing incentives of the license to use state-grown ingredients, especially hops and barley, in their beer. Malting barley has not been grown in New York for about one hundred years, and, until recently, little was known about which barley pathogens would be problematic and what tools would best work to control them in New York. Genetic resistance is one of the most economical and effective ways to manage plant diseases, so cultivars of winter and spring barley were evaluated for disease resistance to natural populations of the pathogens causing scald (Rhynchosporium commune), spot blotch (Bipolaris sorokiniana), leaf rust (Puccinia hordei), powdery mildew (Blumeria graminis f.sp. hordei), and Fusarium head blight (Fusarium spp.). Data were collected from multiple locations over the course of three field seasons to determine the level of resistance each cultivar exhibited for each disease. In this process, spot blotch was identified as a potentially serious threat to spring barley. To prepare for greenhouse evaluations of spot blotch, an aggressive isolate of B. sorokiniana collected in New York was identified, inoculum production techniques were tested, and twelve cultivars were evaluated at seedling and adult growth stages to select susceptible and resistant check varieties. These techniques were implemented to screen a spring two-row barley population composed of diverse elite breeding lines for seedling response to spot blotch to identify quantitative trait loci (QTL) using genome-wide association (GWA) mapping. Two QTL were identified on chromosomes 2H and 7H. The same population was planted in the field, and the lines were evaluated as adults for response to spot blotch, powdery mildew, leaf rust, and Fusarium head blight, using only natural inoculum. One QTL for powdery mildew resistance and two QTL for leaf rust resistance were identified