Effect of Nozzle Type and Water Volume on Dollar Spot Control in Greens-Height Creeping Bentgrass

A field study was conducted in 2007 and 2008 to determine the influence of nozzle type and water volume on the control of dollar spot of greens-height creeping bentgrass, caused by Sclerotinia homoeocarpa F. T. Bennett. The nozzles utilized were XR, TurfJet, Air Induction, Turbo TwinJet, and Turbo Drop Twin Fan, all producing flat spray patterns. For each nozzle type, three flow rates were used to produce water carrier volumes equivalent to 0.5, 1.0, or 2.0 gal/1000 ft². Chlorothalonil (1.8 oz/1000 ft²) was applied on a 14-day interval. Disease was assessed by counting the number of dollar spot infection centers in plot centers where spray coverage was complete. Overall, all nozzles except for TurfJet provided similar dollar spot suppression, and water volume was rarely a factor. On one rating date in 2007, all nozzle-volume combinations reduced dollar spot compared to untreated turf except for the TurfJet nozzles at the lower water volumes. On one date in 2008, all nozzle and volume combinations reduced dollar spot compared to untreated turf, with the exception of plots receiving fungicide through XR and TurfJet nozzles at 0.5 gal/1000 ft² or Air Induction nozzles at 1.0 gal/1000 ft². Therefore, the use of a reduced water volume and an air induction drift reducing nozzle may be a practical option for managing dollar spot with a contact fungicide in creeping bentgrass.