Golf Course Management

JUL 2013

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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Page 83 of 119

Up to Speed by Thomas A. Nikolai, Ph.D. Brush daily? Brushing on golf course putting surfaces has gone in and out of vogue for decades with various styles of brushes used over that time. Browsing through the literature, I found that brushing is recommended for grain reduction, raising stolons to result in smoother surfaces (truer ball roll) and even as a method for reducing Poa annua seedheads. When I was a superintendent in the 1980s, I often used metal brushes mounted out in front of my triplex mower to burn-in vibrant, bold stripes. During the summer of 2012, a putting green brush study was performed at Michigan State University and the University of Tennessee on three different turfgrass species. At Michigan State, the study was performed on creeping bentgrass and Poa annua, while the study at Tennessee was performed on bermudagrass and bentgrass greens. The multiple-site study was a great opportunity for both universities, as very few (if any) mower brush studies have ever been performed and, therefore, most of the attributes of brushing are speculation. The objective of the study, which was funded by The Toro Co., was to determine how forward-rotating and counter-rotating brushes affect the putting surface and the difference between the effects of the two kinds of brushes. To clarify, forward-rotating brushes move in the same direction as the mower reel, while counter-rotating brushes move in the opposite direction of the reel. In addition to the two treatments with different rotational directions of the brushes, a third treatment used another Toro Greenmaster Flex walk-behind mower with no brush attached. At both locations, all research greens were mowed at 0.125 inch with brushes set at 0.100 inch (light) with mowing and brushing six days per week. Greens were lightly dusted with sand once a week with mowing and brushing withheld for 48 hours after topdressing application. Nick Binder of Michigan State and Lucas Freshour at the University of Tennessee were the graduate students in charge of the research. Results from the mowing/brushing study were similar at both sites and on all three turfgrass species. These results included: • Few meaningful differences in regard to green speed; however, the counter-rotating brush tended to decrease green speed a little more than the forward-rotating brush, and the plots that were not brushed were slightly quicker in pace. 78 GCM July 2013 • Signifcantly more topdressing sand was removed with brushing (forward and backward) than without brushing. • On Poa annua, there were no differences in the amount of seedheads among the brush treatments. • The counter-rotating brush decreased the bedknife thickness faster than the forward-rotating brush, and at the conclusion of research at both locations, bedknives were thickest when no brush was used. The objective of the study, which was funded by The Toro Co., was to determine how forwardrotating and counter-rotating brushes affect the putting surface and the difference between the effects of the two kinds of brushes. All parties involved were not anticipating results with more negatives attributed to brushing with none of the perceived attributes being revealed. So what went wrong? Well, nothing. When research results in unexpected outcomes, many skeptics surface and claim the research was not performed correctly. That is how research should work, as this skepticism often leads to continuing research on the practice that will either support or oppose the original fndings. With that said, I would expect the same results from any study that used similar mowing heights with similar brushing depth, frequency and bristle stiffness. However, that is only what I would expect, and I hope to see future studies address this important mechanical practice. Until then, at least brushing remains a great method to burn-in vibrant, bold lines. GCM Thomas A. Nikolai, Ph.D., is the turfgrass academic specialist at Michigan State University in East Lansing, Mich., and a frequent GCSAA educator.

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