Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 2, 2003
Publication Date: October 31, 2003
Citation: Alderman, S.C., Barker, R.E. 2003. Evaluation of resistance to claviceps purpurea in kentucky bluegrass based on incidence and severity estimates. Plant Disease.87:1043-1047. Interpretive Summary: Ergot, caused by the fungus Claviceps purpurea is an important seed disease of Kentucky bluegrass. The preferred method of disease control is through disease resistance. In field plot research, 104 cultivars of Kentucky bluegrass were evaluated for resistance to ergot. Four methods of disease assessment including percentage panicles infected, ergot per panicle, percentage seed infected, and percentage ergot among seed by weight were compared and found to be equally effective for evaluation of ergot. Disease measured as percentage panicles infected is believed to provide a convenient and rapid means of disease assessment that could facilitate the evaluation disease resistance trials, especially when a large numbers of cultivars are included.
Technical Abstract: The susceptibility of 104 Kentucky bluegrass cultivars to C. purpurea (ergot) was assessed based on percentage of panicles with sclerotia (incidence), sclerotia per panicle (severity), percentage seeds converted to sclerotia, or percentage sclerotia among seed by weight. Cultivar ranking within years, in terms of susceptibility, was similar for all disease measurements. Yearly mean disease incidence of ergot among cultivars ranged from 1.0 to 97.5% for susceptible cv. HV102 to 0.0 to 2.5 for resistant cv. Huntsville, with remaining cultivars more or less evenly distributed between the extremes. Yearly mean values of ergot incidence and severity differed significantly among years. Much of this variability was accounted for by days with rain during the period from beginning of flowering to maturity (period of susceptibility). Among the top 40 susceptible cultivars, disease incidence was only moderately correlated (P=0.05 to 0.15) with days with rain in 30 of the cultivars. Duration of flowering was not significantly correlated with ergot level.