Evaluation and genetic analysis of red thread (Laetisaria fuciformis) disease prevalence in tall fescue (Festuca arundinacea)

Abstract

Red thread, caused by [Laetisaria fuciformis (Berk.) Burds.], is a common disease on many cool-season and some warm-season grasses throughout the world. Low reproducibility of experiments under both natural and artificial infection and inadequate understanding of the underlying genetics have limited the selection of turfgrass for resistance to red thread. This study investigated red thread prevalence of tall fescue (Festuca arundinacea Schreb.) populations in two locations over multiple years, estimated disease prevalence in a broad collection of tall fescue populations, and calculated heritability of disease prevalence with two different experimental designs. Collections from Albania and Romania, as well as those that were recently backcrossed to adapted germplasm, were more susceptible to red thread compared with the rest of the populations, highlighting the importance of selection efforts against red thread disease in tall fescue. Narrow-sense heritability (0.52, 0.74, and 0.48) estimated from different experimental designs were all in the range of moderate to high, indicating a large proportion of additive genetic variance in red thread prevalence among tall fescue populations. Hence, prevalence of red thread in tall fescue can be effectively reduced through selection and breeding. This is also the first report documenting the efficacy of family selection in reducing red thread prevalence in tall fescue.