VIEW ARTICLE

Disease Control and Pest Management

Biological Control of Dollar Spot Disease of Creeping Bentgrass. D. M. Goodman, Former graduate student, Department of Environmental Biology, University of Guelph, Ontario N1G 2W1, Canada, Present address: Department of Biology, University of Victoria, P.O. Box 1700, B.C., Canada V8W 2Y2; L. L. Burpee, associate professor, Department of Plant Pathology, University of Georgia, Georgia Station, Griffin 30223. Phytopathology 81:1438-1446. Accepted for publication 19 July 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-1438.

Top-dressing creeping bentgrass with sand-cornmeal or chopped grain colonized by fungi or bacteria was tested as a means of suppressing the intensity of epidemics of dollar spot disease incited by Sclerotinia homoeocarpa. In a greenhouse, 45- to 90-day-old turfgrass grown in cups was top-dressed with 1,500 cm³/m² of sand-cornmeal infested by mycelium of S. homoeocarpa, followed by an equal amount of sand-cornmeal infested by potential antagonists. Four of 24 potential antagonists inhibited the growth of S. homoeocarpa and suppressed disease by 25–90%. In 1987, plots on a closely mown sward of creeping bentgrass were treated with inoculum of S. homoeocarpa and top-dressed weekly with sand-cornmeal (400 cm³/m²) infested by isolates of potential antagonists. Maximum disease intensities (percentage of plot area blighted) were 5, 18, or 44% in plots treated with sand-cornmeal infested by Fusarium heterosporum, an Acremonium sp., or an unidentified bacterium, respectively, during a 35-day epidemic, compared to 84% in plots not top-dressed and 64% in plots top-dressed with noninfested, autoclaved sand-cornmeal. In another experiment, maximum disease intensities were 31% in plots not top-dressed; 9% in plots top-dressed with noninfested, autoclaved chopped grain; or 3–6% in plots top-dressed with chopped grain infested by potential antagonists. In 1988, treatments at 2-wk intervals with sand-cornmeal infested by F. heterosporum (isolate pa 7) at 400 cm³/m² limited disease intensity of a 78-day epidemic of dollar spot to 3%, compared to 18% in nontreated plots. Sterilization of sand-cornmeal infested by F. heterosporum (isolate pa 7) by heating to 70 C for 1 h did not significantly (P = 0.10) reduce efficacy. Results of laboratory and greenhouse experiments suggest that F. heterosporum (isolate pa 7) produces substances toxic to S. homoeocarpa.