Cover St ory
Moss in Turfs? Why? What to Do? By Tom Samples, Ph.D., John Sorochan, Ph.D., Jim Brosnan, Ph.D., Brandon Horvath, Ph.D., and Alan Windham, Ph.D., The University of Tennessee
M
ore than 14,000 species of moss have been identified worldwide. Unlike turfgrasses and most common turfgrass weeds, mosses have no roots or intricate vascular network of conductive tissues (xylem and phloem) to move water, nutrients and sugars from one part of the plant to another. Instead, many are anchored to soil and thatch by threadlike structures called rhizoids, which aid in the uptake of water. Mosses absorb nutrients from their entire aerial surface and are not believed to directly compete with turfgrasses for essential mineral nutrients in the soil. They do, however, intercept sunlight and convert it to chemical energy by way of photosynthesis. Mosses have no flowers and produce no seeds. Instead, they form capsules of spores. The moss lifecycle begins when a spore germinates and chains of cells called 22
protonema begin to grow. Masses of protonema (protonemata) resemble, and may be mistaken for, algae. Eventually, protonemata give rise to gametophores. It is during this lifecycle stage that mosses form stem- and leaf-like structures. The leaf-like structures usually consist of only one single layer of cells, and margins are often toothed. Moss species of the genus Sphagnum are valued components of several soil amendments. Many green-industry professionals, homeowners and gardeners have purchased and used Sphagnum peat to improve the water- and nutrient-holding capacity of landscape soils. Depending on the species from which it is formed, Sphagnum peat can hold about 20 to 30 or more times its weight in water. Mosses range in size from microscopic to 40" or more in length. In turf, they are
TENNESSEE TURFGRASS December/January 2015 Email TTA at: tnturfgrassassn@aol.com
usually very short and grow well below the cutting height. For example, silvery thread moss (Bryum argenteum) can survive in bentgrass and bermudagrass golf greens maintained at a 1/8" cutting height or less. This, like many other moss species, grows in shade or full sun, on concrete surfaces and on damp, compacted soils. In addition to spreading by spores, some mosses may develop from fragments displaced as the turf is mowed or trafficked.
Control measures for mosses in turfgrass Liming Many mosses grow well in acidic soils (pH < 7.0). However, the presence of moss in turfs does not necessarily indicate a need to apply lime. Lime