It’s hard to believe temperatures are forecasted in the upper 50’s in Wooster, Ohio for the next seven days. While creeping bentgrass (Agrostis stoloifera L.) remains dormant, silvery-thread moss (Bryum argenteum Hedw.) is going to take full advantage of this warm winter weather. When water is available and temperatures are >40ºF, silvery-thread moss is actively photosynthesizing, producing new shoots, and gaining a foothold in putting greens. Silvery-thread moss’ lack of temperature-related dormancy is concerning because since January 1st we’ve had 27 days of temperatures >40ºF and 12 days of temperatures >50ºF in Wooster. It’s becoming apparent that moss control strategies may need to continue throughout the winter months to prevent a surge in population growth during unseasonably warm weather.
Many superintendents rely on applications of Quicksilver to keep moss populations in check throughout the growing season. Quicksilver’s active ingredient, carfentrazone-ethyl controls weeds by inhibiting an enzyme involved in chlorophyll synthesis, which eventually results in the breakdown of cellular membranes. Oppositely, a healthy creeping bentgrass plant can rapidly metabolize carfentrazone-ethyl into non-herbicidal compounds; however, during stressful conditions (e.g. low and high temperatures) the enzymes involved in this detoxifying process may not have the ability to metabolize all of the herbicide and injury could occur. During these abnormally warm, moist winter days, silvery-thread moss is active and should be injured by an application of Quicksilver, but what about the creeping bentgrass? From a theoretical perspective, chlorophyll production should be nonexistent if creeping bentgrass is dormant; therefore, no pathway would be available for carfentrazone-ethyl to inhibit, and injury to creeping bentgrass would be unlikely. Because the aforementioned statement is entirely theoretical, we decided to conduct field trials throughout the midwest and eastern United States to determine if a winter application of Quicksilver would injure creeping bentgrass.
To test our objective, researchers applied Quicksilver to creeping bentgrass putting greens at 0, 1.6, 3.3, 6.7, and 13.4 fl.oz. product per acre (Note: 13.4 fl.oz. per acre is twice the label rate). Following the application, researchers will collect NDVI measurements and report any negative effects to the creeping bentgrass. Currently, this study is being replicated by researchers at Ohio State, Rutgers University, Kansas State University, University of Nebraska-Lincoln, and the Chicago District Golf Association. We will monitor the putting greens until mid-June and report the results in the months following!