Occasionally turfgrasses begin to thin out, and moss and algae begin to form. These primitive plants develop because conditions for growing dense, healthy turf have declined.

Mosses are branched, thread-like green plants, which form a tangled, thick mat over the soil. Algae are threadlike green plants, which form a dense, green scum over the soil surface. Neither moss nor algae are thought to be parasitic and both are spread by windblown spores. Both can form crusts on the soil surface, which reduces air and water movement into the soil.

Factors that favor their development include wet and humid conditions and compacted soils with thin turf.

Moss is more common in shady areas with infertile, acidic soils and excessive thatch, while algae are in full sun conditions and fertile soils.

Cultural practices that favor growth of turfgrasses will reduce the competition from moss and algae.

These practices include:

Maintain a good soil fertility and pH: Have the soil tested to determine proper lime and fertilizer needs. For most turfgrasses the pH should be about 6.5.

Improve drainage: Soils that stay moist because of poor drainage should be contoured so water will drain off the area. In some cases, tile drainage may be necessary to correct wet conditions.

Increase light penetration and air circulation: Pruning tree limbs hanging below 10 feet and selected limbs in the crown will improve light penetration and air movement. Also, removing some of the least desirable trees and thinning or removing shrubs will help. Areas surrounded by buildings and vegetation with limbs close to the ground may require considerable work to provide adequate air circulation and light penetration.

Use a shade tolerant grass: If direct sunlight does not reach the ground during the day, an ornamental ground cover may be better suited to the site than a turfgrass like tall fescue.

Cultivate compacted soils: Aeration with a machine that removes plugs of soil will help reduce compaction. Core aerifiers may be rented from various equipment rental companies, or contracted though a lawn service company. Drainage in fine textured soils can be improved by cultivation and adding large amounts of organic matter.

Irrigate deeply and infrequently: Avoid light, frequent irritation. Wait for signs of moisture stress such as the development of a bluish-gray, dull color before irrigating. Then irrigate to wet the soil at least six inches. Most healthy turfgrasses need about one inch of water per week during active growth.

Renovate: Generally turf may be renovated if less than 50 percent of the area has the desired turf. Chemical control can be used to kill off moss and algae if you are planning on renovating. Use products labeled for moss and algae control. Complete as many of the previous cultural control suggestions so growing conditions are changed to favor turf growth and not moss or algae growth.

Michael Wheeler is the Hall County extension coordinator. Phone: 770-531-6988. Fax: 770-531-3994.