Horizontal and Vertical Distribution of spp. in Asymptomatic and Symptomatic Creeping Bentgrass Cultivars.

Dollar spot is an important disease of both cool- and warm-season turfgrasses caused by six fungal species in the genus , yet the ecology and epidemiology of these pathogens remains poorly understood. The goal of this study was to determine the distribution of in asymptomatic and symptomatic creeping bentgrass () in the field using a previously developed quantitative PCR assay. To determine the horizontal distribution of the pathogen, the abundance of spp. was measured in leaf and crown tissue from 90, 1-cm-diameter cores spaced 10 cm apart in May 2019 and 2020 (asymptomatic tissue) and August 2019 and July 2020 (symptomatic tissue). Thirty-seven to 69% of cores sampled from asymptomatic turfgrass and 77 to 95% of cores taken from symptomatic turfgrass yielded positive detections for . Spatial analysis indicated that was randomly distributed in the field in both asymptomatic and symptomatic turfgrass. To assess the vertical distribution of the pathogen, the abundance of was measured in the foliar, crown, and thatch layers of 39, 1-cm-diameter × 2.5-cm-deep cores of creeping bentgrass maintained at fairway height (9.5 mm) during 2019 and 2020. was most abundant in foliar tissue, followed by crown tissue and thatch (lowest abundance) throughout the 2-year study. Both studies provide evidence that is widely distributed in turfgrass swards prior to symptom development and can persist within turfgrass as an endophyte. These findings will improve our understanding of epidemiology and may lead to more sustainable dollar spot management.