Evaluation of Ergot Resistance and Disease Escape in Kentucky Bluegrass Cultivars

Series/Report Number: COARC2016

Abstract: Ergot is an important disease of Kentucky bluegrass seed production in Oregon. The disease is caused by the fungal pathogen Claviceps purpurea, which infects flowers prior to fertilization resulting in the production of sclerotia rather than seed. Sclerotia are the overwintering structures of the fungus and produce airborne ascospores that serve as primary inoculum the following growing season. In some years the timing of ascospore release by the fungus may not coincide with grass flowering (anthesis), which is the only period of host susceptibility, and cultivars with short, uniform flowering periods, or those that flower outside of periods of peak spore production, may potentially escape infection. The objective of this study was to evaluate Kentucky bluegrass cultivars for the potential to escape or resist ergot under central Oregon field conditions. It was hypothesized that cultivars which flower before or after peak ergot spore production, or those with shortened periods of anthesis, would have reduced ergot incidence and severity compared to cultivars with prolonged periods of anthesis or those which flower when ergot spores are present in large numbers.