Trials were conducted at the Iowa State University Horticulture Station near Gilbert. Fungicides were applied to creeping bentgrass maintained at 0.16-inch cutting height, using a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal per 1,000 sq ft. The experimental design was a randomized complete block with four replications. All plots measured 4 ft x 5 ft. The entire plot was inoculated with pathogen-infested rye grain on 8 Jun. Spray applications were initiated on 15 Jun in all subplots, then re-applied at recommended intervals on 5 and 13 Jul. The spray regime was suspended on 13 Jul because of absence of dollar spot symptoms. The entire plot was inoculated again on 14 Aug. All subplots were sprayed on this date and on 28 Aug.

Dollar spot symptoms were first observed on 27 Jun. Most products suppressed dollar spot significantly in comparison to the unsprayed control on 27 Jun and on 23 and 31 Aug. No phytotoxicity symptoms were observed during the trial.

Fungicide products, application rates and intervals, and dollar spot severity at the ISU Horticulture Station, 2001