Evaluation of Conventional and Alternative Products for Silvery-thread Moss Control in Creeping Bentgrass

Silvery-thread moss (Bryum argenteum Hedw.) is a common weed in creeping bentgrass (Agrostis stolonifera L.) putting greens, and control strategies alternative to the conventional use of synthetic pesticides may be useful. Spot-spray treatments of sodium bicarbonate (SB, 22.5 and 45 g ai/liter), potassium bicarbonate (PB, 22.5 and 45 g ai/liter), and essential oil (Moss Buster, 1% essential oil of oregano, ready-to-use), as well as broadcast treatments of SB (55 and 110 kg ai/ha), PB (4.8, 11.4, and 93.5 kg ai/ha), and carfentrazone-ethyl (CE, Quicksilver, 0.09 kg ai/ha) were applied twice in the spring and fall of 2009 and 2010 (4 applications each year). Moss severity and creeping bentgrass color were assessed biweekly. Spot application of SB or PB (45 g ai/liter), essential oil, and broadcast treatment with CE suppressed moss 39% to 55% in 2009. Broadcast applications of SB or PB were not effective either year. Creeping bentgrass treated with spot application of SB or PB (45 g ai/liter) required up to 8 days to recover to acceptable color, whereas bentgrass treated with essential oil required up to 18 days. Bicarbonate and essential oil products can reduce moss severity at a similar level to CE, but rates and/or application methods may need to be adjusted to avoid injury to creeping bentgrass putting greens.