ALGAE

algal growth in turf	Characteristic	Description
	Host Grass Species	all turfgrasses; most problematic on putting green turf

 

Note: Still not sure if this is the right disease? The Turfgrass Disease Identification program may be helpful. Or consult the experts at the Turf Diagnostics Lab. Check the TurfFiles glossary for definitions of unfamiliar terms.

FACTORS AFFECTING DISEASE DEVELOPMENT

Algae may develop whenever thinning of the turf canopy permits sufficient air, light, and water to reach the thatch surface. Algal growth is most aggressive during the late spring, summer, and early fall when warm, humid conditions are conducive to algae growth and turf thinning. Low mowing heights, shady conditions, poor soil drainage, and frequent irrigation also encourage algal growth in the turf canopy.

Algae have historically been thought of as secondary colonizers, meaning that they only fill-in areas where turf density has been reduced by some other problem. However, mounting evidence indicates that high levels of algae activity can directly cause thinning of putting green turf, possibly by production of toxins or competition for air, water, and nutrients. An aggressive algae management program can greatly increase the density and overall quality of putting greens during periods of warm and humid weather.

CULTURAL CONTROL

Maintenance of dense, healthy turf is the most effective way to prevent algae invasions. Avoid establishing turf in areas that are heavily shaded or poorly drained, or take steps to correct these problems in established turf. Mow at the recommended height for each turfgrass species, and increase mowing heights in shady areas to compensate for the reduced light levels. Irrigation should be applied deeply and infrequently; apply sufficient water to wet the entire root zone, and then reapply as needed when the turf shows signs of wilt. Putting greens and other heavily trafficked areas must be cultivated regularly to maintain soil drainage and aeration.

CHEMICAL CONTROL

Ammonium sulfate, hydrated lime, or other materials can be applied to “burn” the algae in infested areas. Extreme caution is needed when doing this, especially on golf course putting greens, as these materials can also burn the turf or cause nutritional imbalances in the soil.

The fungicides chlorothalonil and mancozeb are also effective algaecides. These products will control algae on a preventative or curative basis, but preventative applications are much more effective. Repeat applications on a 10 to 14 day interval during warm, humid weather provides excellent algae control and significantly increases the density of putting green turfgrasses. Note that chlorothalonil and mancozeb are not approved for application to residential lawns.

Fungicides containing copper hydroxide should be used with caution, as copper can accumulate in the soil to toxic levels after repeated applications. For this reason, copper hydroxide should only be used under extreme circumstances to bring severe algae infestations under control.

Once a severe algae infestation has occurred, fungicide applications alone will not provide acceptable control. Additional steps must be taken to physically break-up the mat of algal growth so that the turf can recover. Spiking, aerification, verticutting, topdressing, or combinations thereof are effective ways to accomplish this.

© North Carolina State University. This information sheet was prepared by Fred Yelverton, Gail G. Wilkerson, Leon Warren, Travis Gannon, and Gregory S. Buol. Department of  Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared November, 3, 2008. Available on-line at www.turffiles.ncsu.edu. This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.