Impact of Irrigation Regime and Host Cultivar on Dollar Spot of Creeping Bentgrass

Dollar spot, 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, based on timing and frequency, as well as creeping bentgrass cultivar, on dollar spot incidence in creeping bentgrass turf managed as a fairway. Irrigation was applied at either 10 p.m. daily or twice weekly, or 5 a.m. daily, on fairway plots established to each of three creeping bentgrass cultivars; Declaration, Flagstick and L-93. Total weekly irrigation volume was approximately the same among all treatments.

Declaration and Flagstick were considered resistant to dollar spot and L-93 was considered susceptible. Plots watered at 10 p.m. daily exhibited significantly less disease than those irrigated at 10 p.m. twice weekly, regardless of creeping bentgrass cultivar. Flagstick developed the least amount of dollar spot each year among all cultivars. In 2011 and 2013, the Flagstick plots receiving daily irrigation (a.m. or p.m.) did not significantly differ and exhibited less dollar spot than those irrigated at 10 p.m. twice weekly for the same cultivar.

These data indicate that daily watering decreases the amount of dollar spot infection in creeping bentgrass fairway turf compared to twice-weekly waterting.