Mosses are primitive plants (bryophytes) that lack a vascular system. They are rapid invaders of areas where turf density is low, especially when surface moisture is high because of frequent rainfall, overirrigation, and/or poor soil drainage

Causal agent

Silvery thread moss (Bryum argenteum)

Primary Hosts

Areas where turf density is low. Moss is primarily a problem in turfgrasses maintained as putting greens.

Disease Cycle

Mosses spread through the dispersal of spores or vegetative fragments. Once established, they form dense perennial colonies of vegetative growth, competing with the surrounding turfgrass. Mosses can survive in a dehydrated and dormant state during periods of heat or drought, resuming growth when conditions become favorable.

Epidemiology

Moss invasions are influenced by the following factors:

• frequent rainfall
• overirrigation
• poor soil drainage
• reduced turfgrass growth

Wet and shady areas with low-cut turf are more susceptible to moss infestations. Silvery thread moss, in particular, has been favored by reduced mowing heights and frequent applications of irrigation and foliar nutrients on golf course putting greens.

Symptoms

Moss invasions in turfgrass areas are characterized by the presence of dense moss colonies. Mosses may form a carpet-like layer over the turf, especially in areas with low turfgrass density. The symptoms include a visual shift from turfgrass dominance to moss dominance. Mosses can give the turf a greenish appearance and create an uneven or patchy surface.

Credit: John Kaminski/Penn State University

Figure 15.3.2: The presence of moss is actually the sign of the organism itself. (a) Research trials have shown that herbicides can provide exceptional control. (b) Moss can grow very low and cause bumpiness of bentgrass greens. In the spring, (c) fruiting bodies are formed and (d) germinate to release more moss spores into the environment.

 

Management

Effective management of moss invasions involves both cultural and chemical practices. Cultural practices focus on creating conditions that favor turfgrass growth over moss. Chemical control treatments are most effective when applied to actively growing moss in spring and fall. Physical disruption of the moss colonies, combined with promoting turfgrass growth, can enhance the long-term efficacy of moss control programs.

Cultural

Cultural management practices aim to create an environment that favors the growth of turfgrass while discouraging moss.

Strategies include:

• improving surface infiltration
• reducing light
• reducing irrigation
• adjusting fertilizer applications based on soil tests
• promoting sunlight penetration
• improving air movement
• mowing at recommended heights for the specific turfgrass species

Chemical

Chemical control options include the use of the following:

• iron sulfate
• calcium or potassium bicarbonate
• quaternary ammonia
• specific soaps
• herbicides, including carfentrazone-ethyl (Quicksilver)
• fungicides

Iron sulfate, calcium or potassium bicarbonate, quaternary ammonia, and specific soaps may be used to burn the moss, but generally the moss recovers and therefore they are not generally a long term solution.