Ideas for Moss Control

Moss continues to be a problem throughout Ohio on golf greens in shade or full sun. Below I have tried to summarize some of the moss control treatments that we have done over the years (since 1993) in attempting to control moss. Not all of the conceivable treatments are listed, and the comments are based on our research. Obviously, there are other researchers and practitioners who are also conducting research who may have a better insight.

General Comments:

¥ Mosses are primitive plants that have changed little over the course of history.

¥ There are numerous species of moss that can colonize golf green.

¥ Mosses grow where other plants can't. Thus, if moss is present, something is not ?right?.

Photograph 2. Close-up of moss spores in early spring.

Treatment Summarization (note: Check to see if labeled for moss control)

Ammonium sulfate- In our studies fall and spring applications of ammonium sulfate alone or in combination with ferrous sulfate has resulted in significant reduction in moss. The most effective rate has been 0.75 pounds actual nitrogen per 1000 sq.ft. per month. In studies where we tried to reduce the rate of ammonium sulfate (0.1 to 0.25 pounds per 1000 sq.ft. per month) resulted in minor reduction. Compared to other nitrogen sources ammonium sulfate was the most effective. The potential of burn does exist with ammonium sulfate when applications are made during high temperatures.

Photograph 3. Monthly applications of ammonium sulfate in the spring resulted in moss discoloration.

Photograph 4. Closeup of ammonium sulfate applications on the right and the control on the left.

Ferrous sulfate-At rates as high as 7.0 ounces per 1000 sq.ft. per month during the spring and fall we observed a blackening of the moss and an initial decline only to have it come back.

Hydrated lime-Hydrated lime has been reported to reduce moss populations on greens in the Northeast. In our studies, using rates between 3.0 and 10.0 pounds per 1000 sq.ft. we observed some reduction in moss but not a significant reduction. We did however see a significant phytotoxic affect.

Dawn Ultra® - In Ohio, Frank Dobie at the Sharon Club did extensive work with soaps and other combinations and reported excellent results in reducing moss. Superintendents around the state have modified and used this product with some success. In our studies, we have seen reduction in moss in some of our studies and not others. Using 2.0 ounces per gallon we have found that applying with a watering can or spray bottle is much more effective than spraying through a boom sprayer. We have observed phytotoxic affects with this product when applied during the summer.

Chlorothalonil - In 2001 using Daconil Ultrex® we saw a significant reduction in moss (~75%) when applied biweekly beginning in early June. In 2002 again we have seen a reduction in moss but not as drastic (~15%). However, treatments were not started until June 26th. I think for most effective reduction in moss using chlorothalonil treatments need to be initiated in mid spring and continued through summer on a biweekly schedule. Given the restriction on chlorothalonil use, this practice may not be possible.

Terracyte® - This product is sodium perchloride and lime based. We have only looked at this product for one year (2002). This product however has resulted in a reduction in moss. We have made summer treatments on weekly bases, which are probably not as effective as fall treatments. Research at Cornell University has demonstrated a significant reduction in moss with fall applications of this treatment on four consecutive days.

Junction® - This product is a combination of copper hydroxide and mancozeb. In weekly applications of 4.0 ounces per 1000 sq.ft. we have observed a reduction in moss. In studies at Cornell University Junction ¥ has reduced moss when applied in the fall and the best results are achieved when applied in 2 gallons of water per 1000 sq.ft. In our studies when applied repeatedly during the summer stress period we observed a decline in bentgrass quality. It appears the higher the temperatures the more discoloration of the creeping bentgrass can occur. This product may be an effective tool in the northern United States but may cause some problems on creeping bentgrass in the southern United States (see the 4/2/01 SK message entitled "Caution When Using Junction®".

Authors: Karl Danneberger