Control of Typhula Blight and Pink Snow Mold of Creeping Bentgrass and Residual Suppression of Dollarspot by Triadimefon and Propiconazole. L. L. Burpee, Department of Environmental Biology and the Guelph Turfgrass Institute, University of Guelph, Guelph, Ontario N1G 2W1 Canada. A. E. Mueller, and D. J. Hannusch. Department of Environmental Biology and the Guelph Turfgrass Institute, University of Guelph, Guelph, Ontario N1G 2W1 Canada. Plant Dis. 74:687-689. Accepted for publication 19 March 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0687.

Two triazole fungicides (triadimefon and propiconazole) were compared with pentachloro-nitrobenzene (PCNB) for control of Typhula blight and pink snow mold of creeping bentgrass. In an experiment repeated in consecutive years, propiconazole applied at rates of 3.0, 6.0, or 12.0 kg a.i./ha, or triadimefon applied at 12 kg a.i./ha, suppressed the development of Typhula blight and pink snow mold to levels that were not significantly different from disease intensity in plots treated with PCNB at 30.0 kg a.i./ha. Triadimefon, applied at 1.5, 3.0, or 6.0 kg/ha, suppressed Typhula blight, but not pink snow mold, to levels equivalent to those provided by PCNB. Eight months after application, significant residual suppression of dollarspot disease was observed in plots treated with 3, 6, or 12 kg a.i./ha of triadimefon or 12 kg a.i./ha of propiconazole in 1985 or with 12 kg a.i./ha of either fungicide in 1986. A consistent, but nonsignificant (P = 0.05), increase in the intensity of dollarspot was observed in 1986 and 1987, 8 mo after application of PCNB.

Keyword(s): gray snow mold, turfgrass, iatrogenic disease, reduced pesticide use.