Golfdom, January 2012

M I T I G A T I N G M O S S Alternative Products for Silvery Thread Moss Control in Creeping Bentgrass S ilvery thread moss is a common weed in creeping bentgrass putting greens Quicksilver carfentrazoneethyl has been found to reduce silvery thread moss populations and has become a standard for comparison for alternative moss control strategies Numerous studies have evaluated alternative products for silvery thread moss suppression Dishwashing detergent Dawn Ultra Ajax and hydrated lime have been found to reduce moss populations however phytotoxicity of creeping bentgrass has been an issue Several researchers have reported moss suppression with baking soda Settle et al found that baking soda dissolved in water and applied with a hand held trigger spray bottle to wet moss colonies twice two weeks apart in the spring effectively controlled moss for the entire season Kennelly et al reported that spot treatment with baking soda at the same interval as Settle was as effective in moss suppression as Quicksilver However slight phytotoxicity to creeping bentgrass on the moss colony margins was observed for up to 14 days after treatment More research is needed into alternative products for silvery thread moss control Lower concentration spot treatments of baking soda and similar products may reduce moss populations while minimizing phytotoxicity to creeping bentgrass It may also be possible to use baking soda in broadcast applications to reduce labor Alternative silvery thread moss controls A field study was conducted in 2009 and 2010 at the Rocky Ford Turfgrass Research 36 TURFGRASS TRENDS January 2012 www turfgrasstrends com Center in Manhattan Kan Treatments consisted of an untreated control and eleven spot or broadcast applications baking soda applied as a spot spray at 3 and 6 oz gal 1 or as a broadcast at 18 and 36 oz per 1000 square feet Armicarb potassium bicarbonate applied as spot sprays at 3 or 6 oz per gallon or as broadcast treatments at 18 44 and 36 oz per 1000 square feet Moss Buster ready to use 1 essential origanum oil i e oil of oregano was applied as a spot spray following label instructions and Quicksilver broadcast at 014 oz per 1000 square feet Spot spray treatments were applied to individual colonies with a hand held triggerspray bottle until moss colonies were visibly wet Broadcast sprays were applied using a hand held CO 2 powered sprayer Baking soda 18 and 36 oz per 1000 square feet and Armicarb 44 and 36 oz per 1000 square feet were applied in a water carrier rate equal to 6 gallons per 1000 square feet to increase the coverage and uniformity of applied treatment solutions while Armicarb 18 oz per 1000 square feet and Quicksilver 014 oz per 1000 square feet were applied following label specifications at water carrier rates equal to 25 gallons per 1000 square feet and 2 gallons per 1000 square feet respectively All treatments were applied twice in the spring and fall of each year with two weeks between application dates Plots were rated every two weeks for percent moss coverage and creeping bentgrass color from May 12 to October 20 2009 and from May 14 to October 13 2010 Creeping bentgrass color data were also collected 1 and 7 days after treatment Entire plots were rated for creeping bentgrass color using a 1 to 9 scale with 1 being totally brown 6 minimum acceptable color and 9 optimum green color Percent moss coverage was rated visually by estimating the percent of each plot infested by silvery thread moss Percent moss coverage differed among plots at the beginning of the study in each year Thus moss coverage was considered to be 100 at the time of the initial rating and moss severity for later rating dates was scaled accordingly Area under the curve AUC By Cole Thompson Jack Fry and Megan Kennelly