Trials were conducted at the Iowa State University Horticulture Research Farm near Gilbert, Iowa. Fungicides were applied to ‘Penncross’ creeping bentgrass maintained at 5/32-inch cutting height, using a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1,000 ft². The experimental design was a randomized complete block with four replications. All plots measured 4 ft x 5 ft. Four days after inoculation of the entire plot with rye grain infested with the dollar spot pathogen, fungicide applications began on 14 Jun. Subsequent applications were made on 28 Jun, 5, 12, and 26 Jul, and 9 Aug. The plot was re-inoculated with infested rye grain on 10 Jul.

Dollar spot symptoms appeared in the plot within 2 weeks after the first spray application. Disease development was slight in early July, which prompted re-inoculation. Disease pressure did not subsequently increase above the level of early July, however. Most treatments on 1 Jul, and all treatments on 19 Jul and 18 Aug, exhibited significantly less disease than the untreated check. No phytotoxicity symptoms were observed during the trial.

% plot diseased*

Untreated check ----- 4.03 3.00 1.42

Spectro 90WDG, 2 oz 14 0.00 0.00 0.00

Spectro 90WDG, 4 oz 14 0.00 0.00 0.00

Spectro 90WDG, 8 oz 14 0.00 0.00 0.00

Bayleton 50DF, 0.25 oz 14 0.65 0.00 0.00

+Daconil Ultrex 82.5 WDG, 1.82 oz

Lynx 45 WP, 0.28 oz 14 0.18 0.00 0.00

+Daconil Ultrex 82.5 WDG, 1.82 oz

Bayleton 50 DF, 0.25 oz 14 0.08 0.00 0.00

Lynx 45WP, 0.28 oz 14 0.50 0.00 0.00

DAS0076 Confidential 1.75 0.00 0.03

DAS0076 Confidential 2.50 0.00 0.00

DAS0076 Confidential 0.80 0.00 0.00

DAS0076 Confidential 1.25 0.00 0.88

Eagle 50WP, 0.5 oz 14 0.00 0.00 0.00

Chipco 26GT 2SC, 4 fl oz 14 0.38 0.00 0.00

Chipco Signature 80WG, 4 oz 14 3.50 0.50 0.68

Chipco 26GT 2SC, 4 oz 14 0.20 0.00 0.00

+Chipco Signature 80WG, 8 oz

TM-41702 40WP, 1.88 lb/A 14 0.50 0.00 0.13

TM-41702 40WP, 1.88 lb/A 21 0.90 0.13 0.50

TM-41702 40WP, 1.25 lb/A 14 0.75 0.25 0.18

*Mean of 4 subplots

**P = 0.05