Released July 9, 2009

FAYETTEVILLE, Ark. – July’s hot days and rainy spells are the perfect conditions for a fungus to cause brown patch in tall fescue lawns, according to Aaron Patton, extension turfgrass specialist with the University of Arkansas Division of Agriculture.

"Brown patch of tall fescue typically occurs during the summer when the fungus becomes active during hot, humid days and nights," he said. "Extended dew periods and nighttime irrigations favor disease activity."

The symptoms are easy to spot: the lawn will have brown patches, in some cases forming circles or rings with healthy grass inside. Patton cautions it’s easy to confuse brown patch with symptoms of drought stress, or another fungus that causes dollar spot.

The best defense may start before the lawn is planted.

"Choose a seed blend or mixture containing tall fescue cultivates that have a low brown patch incidence and severity," he said. "It may also be wise to choose tall fescue seed mixtures that contain 10 percent Kentucky bluegrass.

Patton said bluegrass is not as susceptible to brown patch and recuperates faster from disease than tall fescue.

Other tactics include avoiding nitrogen fertilizers in June, July or August, since nitrogen encourages growth and watering deeply, but infrequently, to reduce moisture.

However, fungicides may be necessary in some areas.

"These materials are most effective when applied on a preventative program, beginning when conditions favor disease onset," Patton said. "Materials containing the active ingredients propiconazole, triadimefon and myclobutanil are registered for brown patch."

Homeowners who elect to use fungicides, should consider using a professional lawn company that has appropriate application equipment, he said.

For more information about brown patch, see publication FSA7558 at http://www.uaex.edu.

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http://www.uaex.edu/news/july2009/0710brownpatch.htm

Contact: Elizabeth Fortune, (501) 671-2120, efortune@uaex.edu