Algae and Turfgrass

Curtis Swift, Ph.D., Colorado State University, Tri River Area


A mass of algae collected from a lawn.

Masses of greenish to brownish globs of algae that form on the soil surface can damage turf by suffocating grass plants and their roots. As these gelatinous deposits dry they form tough black crusts that crack and peel off in sheets. This problem is more common in thin, shaded, over-fertilized, and over-watered turf than in well-drained, healthy turf. Compacted areas, especially where water stands, are especially susceptible. Proper soil preparation prior to seeding or laying sod, selecting the proper grass for the site, fertilizing properly and following other proper cultural techniques helps reduce problems with algae.

Maintaining a thick turf even in areas where shade is a problem, and avoiding water-logged soil and over-watering reduces problems with algae. Watering in late afternoon or early evening has been reported to increase problems with algae. Improving drainage through a vigorous aeration/core cultivation program is recommended. Top dressing to fill the aeration holes will improve drainage if the proper material is selected to fill the aeration holes. Applications of diluted solutions of sodium hypochlorite or liquid household beach (0.01%), copper sulfate (2 to 3 ounces per 1000 square foot area) are recommended treatments. Daconil (chlorthalonil) and Fore (mancozeb) are fungicides labeled for the management of algae.

When algae seal the soil surface and/or the spaces between the soil particles it fosters the development of a condition called anaerobiosis (an anaerobic environment caused by the presence of biotic/living organisms). In sandy soils this creates ‘Black Layer’, a film of bacteria an inch or so below the soil surface. This oxygen depleted environment, results in a toxic situation and subsequent root death. Deep aeration along with proper watering helps correct ‘Black Layer’, a widespread problem in sports turf management.

Smith (1988) reported the development of these anaerobiotic layers were more prevalent when urea was used as a fertilizer when compared with either ammonium nitrate or ammonium sulfate. Smith also found the addition of sulfur to a urea or ammonium sulfate application increased the severity of Black Layer.

As with the correction of algal formations on the soil surface, alleviation of problems with Black Layer is through proper turf management to include aeration.

References:

Beard, J.B. 1973. Turfgrass: Science and Culture. Prentice-Hall Inc. Englewood Cliffs, N.J.

Couch, H.B., 1995. Diseases of Turfgrasses: Third Edition. Krieger Publishing Company, Malabar, FL.

Schumann, G.L., Vittum, P.J., Elliott, M.L., Cobb, P.P. 1998. IPM Handbook for Golf Courses. Ann Arbor press, Inc. Chelsea, MI.

Shurtleff, M.C., Fermanian, T.W., & Randell, R. 1987. Controlling Turfgrass Pests. Prentice-Hall, Inc. N.J. 449 pages.

Smith, J.D. 1988. Black plug layer on Saskatchewan golf courses. Greenmaster 24(8): 6-11, 21.