Dollar spot (DS), caused by Sclerotinia homoeocarpa, is an important disease of turfgrass. Irrigation practices and host resistance can impact disease incidence and aesthetics on fairway turfgrass. This study was conducted to determine the impact of irrigation regime and creeping bentgrass cultivar on DS incidence as well as vegetative compatibility group (VCG) of the pathogen. Irrigation was applied at either 2200 h daily or twice weekly, or 0500 h daily to three creeping bentgrass cultivars, `Declaration', `SRP-1WM', and `L-93'. `Declaration' and `SRP-1WM' were considered resistant to DS and `L-93' was considered susceptible. Plots watered at 2200 h daily exhibited significantly less disease than those irrigated at 2200 h twice weekly, regardless of creeping bentgrass cultivar. `SRP-1WM' developed the least amount of DS each year among all cultivars. In 2011 and 2013, the `SRP-1WM' plots receiving daily irrigation (AM or PM) did not significantly differ and exhibited less DS than those irrigated at 2200 h twice weekly for the same cultivar. Recovered isolates of S. homoeocarpa were scored for VCG based on barrage zone formation to determine if irrigation regime or creeping bentgrass cultivar corresponded uniquely to VCG. Results indicated that VCGs B and F, averaging 45 and 33% overall, respectively, were the most predominant pairing regardless of irrigation regime or host cultivar. These results indicate that specific irrigation regimes or host cultivars investigated in this study similarly influenced VCG.
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