INVESTIGATIONS OF POTENTIAL BIOLOGICAL AND CHEMICAL CONTROLS FOR SILVERY THREAD MOSS ON PUTTING GREENS. A. Post*, S. Askew, and D. McCall, Virginia Tech, Blacksburg, VA (53)
Since the loss of mercury and other heavy metal based herbicides silvery threadmoss (Bryum argenteum) has become an increasing problem on golf course putting greens. Superintendants continue to reduce mowing heights and fertility on putting greens to meet golfer demands for faster playing surfaces. This creates optimal conditions for competitive displacement of creeping bentgrass by silvery threadmoss. Only one herbicide, carfentrazone (Quicksilver) and two fungicides, chlorothalonil (Daconil) and mancozeb (Manzeb) are labeled for moss control on putting greens currently. The objective of this study was to widely screen available crop protection chemicals for effects on silvery threadmoss and provide new options for its control on golf course putting greens.
Two trials were initiated to examine herbicide effectiveness on silvery threadmoss. Each was a randomized complete block design with ten replications and forty-nine herbicide treatments applied at one and two times the labeled use rates as well as a nontreated control. After herbicide treatment, moss plugs were randomly placed into 24-well cell culture plates where they remained for the duration of the study. Digital photos were taken for image analysis at 0, 3, 7, 10, 14, 21, and 28 days after treatment (DAT). Each one was then cropped to include a single plot per image. Data was captured in Sigma Scan Pro 5 and managed in ARM 8. Sigma Scan was set to count green pixels in a range from hue=38 to 100 and saturation=0 to 100. When compared to the zero-day after treatment pixel counts this provides a % reduction in green color for each moss plug which equates to a measure of control. Data were subject to ANOVA and means separated by fishers protected LSD (p=0.05). Herbicides which significantly reduced green color included: carfentrazone, flumioxazin, MSMA, glufosinate, sulfentrazone, and an experimental. By 10 DAT, several herbicides reduced green color by more than 90% including flumioxazin, carfentrazone, fosamine, diquat, and sulfentrazone. Successful treatments will be examined in the field next growing season to evaluate their efficacy and safety for potential supplemental registrations.