TURF TALK
WITH ALTERNATIVE PRODUCTS ON A CREEPING BENTGRASS PUTTING GREEN By P. H. Dernoeden and C. P Ryan, Dept. Plant Science and Landscape Architecture, University of Maryland riven by environmental concerns and the high costs of conventional fungicides, golf course superintendents are looking for alternative products to combat turf diseases. This study evaluated such products for their ability to control dollar spot (Sclerotinia homoeocarpa) in creeping bentgrass (Agrositis stolonifera). In recent years, studies have reported very good dollar spot control with Civitas, a mineral-oil product developed by Petro-Canada. Since Civitas can yellow turf, however, it is mixed with a green colorant called Harmonizer to mask any potential discoloration. In our study, Civitas and Harmonizer were applied separately, as well as in a tank-mix combination as recommended by the manufacturer. In addition, Civitas and Harmonizer were tank-mixed with Curalan (vinclozolin) to determine any potential benefits of using this combination. The following products were also evaluated in this study: • DewCure, a wetting agent (marketed by Mitchell Products) reported to suppress dollar spot severity • Phosphite 30 (56% mono and di-potassium salts of phosphorus acid, marketed by Plant Food Co., Inc.), a fungicide that targets Pythium blight • Lesco’s 12-0-0 Plus Micronutrients product, commonly
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Photos, top-to-bottom: Photo 1 – Dollar spot in creeping bentgrass. Photo 2 – Dollar spot infection center in creeping bentgrass. Photo 3 – Our research study area for alternative products for dollar spot control. Photo 4 – Top left: Curalan. Top right: Civitas. Bottom left: Harmonizer alone. Bottom right: Civitas + Harmonizer.
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MTC TURF NEWS
used on golf courses in the MidAtlantic region, but has not been assessed for its potential to reduce dollar spot severity • Fore Rainshield (i.e., mancozeb, Dow AgroSciences), one of a few contact fungicides available for use on turf Among contact fungicides, only chlorothaonil (i.e., Daconil) is used extensively to target dollar spot, especially in resistance-management programs. The level of dollar spot control that can be achieved with Fore Rainshield has not been assessed in Maryland, but an assessment is warranted, given the need for more contact fungicides for use in S. homoeocarpa resistance-management programs. If Fore Rainshield can provide significant levels of dollar spot suppression, it may be useful as a potential replacement, or occasional substitute for, chlorothalonil in tank-mixes to sites with known resistance or reduced sensitivity issues. The same argument can be made for Civitas, DewCure, Lesco 12-0-0 and Phosphite 30, if they have good activity on S. homoeocarpa.
Research methods and materials This study was conducted at the University of Maryland Paint Branch Turfgrass Research Facility. Treatments were applied with a CO2 pressurized (35 psi) sprayer equipped with