Inheritance of summer patch disease tolerance in hard fescue ( Festuca brevipila Tracey)

Hard fescue ( Festuca brevipila Tracey) is a cool‐season turfgrass known for exceptional performance under low‐maintenance conditions. However, it is susceptible to summer patch disease. Summer patch is a root disease caused by Magnaporthiopsis poae and Magnaporthiopsis meyeri‐festucae . The objective of this study was to investigate the inheritance of summer patch tolerance in controlled crosses of hard fescue. The experimental populations were full‐sib families created by crossing three tolerant and three susceptible parents in a diallel cross. One hundred progeny from each of the 15 crosses and reciprocals were established in a mowed spaced‐plant trial in 2017 (Trial 1) and 2019 (Trial 2). All progeny and selected parental genotypes were arranged in a randomized complete block design with four replications and inoculated with a mixture of an M. meyeri‐festucae isolate (SCR9) and an M. poae isolate (C11). The disease severity of hard fescue genotypes was assessed by visual rating during the summers of 2018, 2019, 2020, and 2021. Variation in disease responses among progeny suggests that inheritance is controlled by a few major genes. The progeny phenotypes were correlated to the parental phenotypes. The estimate of narrow‐sense heritability was 0.20 (± 0.01), while the estimate of broad‐sense heritability was 0.67 (± 0.08). The heritability estimates are modest but indicate the potential for summer patch tolerance to be improved via selection and breeding. This is the first report of heritability estimates for summer patch tolerance in any turf species. This research will help to determine the most efficient selection procedures for summer patch tolerance in hard fescue. This is the first report documenting the heritability and gene action of summer patch tolerance in hard fescue. Evidence showed summer patch disease could be reduced through breeding. Pre‐selection of parental genotypes and determination of combining ability is important to guarantee the efficacy. Hard fescue is a type of turfgrass that grows well under low‐maintenance conditions, but it is vulnerable to a disease called summer patch, which affects its roots. This study aimed to understand how tolerance to summer patch disease is passed down from parent plants to their offspring in hard fescue. By crossing different hard fescue plants—some tolerant to the disease and some not—researchers observed how the disease affected their offspring. They found that the ability to tolerate the diseas