Genotypic variation for snow mold reaction among creeping bentgrass clones

Creeping bentgrass (Agrostis stolonifera L.) is currently the most desirable grass for golf courses in temperate climates. In temperate climates, creeping bentgrass is highly susceptible to snow mold fungi which can cause significant injury and mortality. The objectives of this study were to survey a collection of creeping bentgrass clones for reaction to snow mold fungi (Typhula spp.), to identify clones with potential resistance to snow mold fungi, and to identify ecological factors related to necrotic reactions of creeping bentgrass clones to snow mold fungi. Three hundred sixty creeping bentgrass clones, selected from old golf courses in Wisconsin, were evaluated for necrosis reaction during incubation and recovery periods following inoculation with Typhula ishikariensis Imai or as noninoculated controls. Genotypic variation was observed for tolerance to snow mold and cold, dark (noninoculated) conditions but the two tolerances were uncorrelated with each other. Clones from fairways were more tolerant of snow mold, most likely due to long-term natural selection in the absence of fungicide applications. In a second experiment involving 72 selected clones, selection was successful in identifying divergent groups of clones, although differences between experiments indicated that future selection and breeding should make use of multiple inoculation runs. Resistance to snow mold in creeping bentgrass appears to be nonspecific with respect to race and species of snow mold isolates.