Lightweight Rolling and Sand Topdressing to Decrease Fungicide Inputs and Dollar Spot Severity on Fairways.

Dollar spot (Sclerotinia homoeocarpa F.T. Bennett), the most common turfgrass disease in the upper Midwest, affects turfgrass quality, decreases golf course playability, and results in millions of dollars spent on frequent fungicide applications. Michigan State University scientists observed reduced dollar spot infection in putting greens that were rolled several times weekly. Others observed reduced incidence of disease in putting greens treated with sand topdressing. We hypothesized that dollar spot infection on fairways would be decreased by sand topdressing and by rolling thereby reducing the need for frequent fungicide treatments. Our objective was to examine dollar spot severity responses on an Agrostis stolonifera L. and Poa annua L. fairway to lightweight rolling and sand topdressing with and without fungicide applications. The study was conducted from 2011 through 2014 at the Hancock Turfgrass Research Center at MSU using a split block design, and treatments consisted of sand topdressing, three rolling frequencies (1x, 3x or 5x weekly), a control, and three replications. In 2013 and 2014, fungicide application treatments were introduced, and consisted of Emerald¨ at 0.1374, 0.2748, and 0.5495 kg/ha, rolling 3x weekly, sand topdressing, and controls. Infection was visually estimated. Sand topdressing significantly (P < 0.05) reduced infection by 40 to 50% at the peak of the dollar spot infection cycle in 2011 and 2013. Moreover, the 3x and 5x weekly rolled treatments exhibited 50% less dollar spot injury in 2013. First year data results showed no interaction effects of sand topdressing and rolling on fungicide efficacy; however, preliminary results from this study suggest that sand topdressing and lightweight rolling could reduce the need for frequent fungicide inputs to manage dollar spot on fairways.

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