Properly identify brown patch

March 8, 2019 -  By
Photo: Lane Tredway

Brown patch typically varies in color from yellow to brown. Photo: Lane Tredway

For Kevin Herrmann, brown patch is a disease that comes with the turf territory. The general manager of the Raleigh, N.C.-based Fairway Green Lawn & Shrub Care, says, “Pretty much every fescue lawn in the summer in North Carolina is going to have brown patch.”

The basics

Brown patch fungus is mostly a concern for turfgrasses in the Transition Zone and south, and it’s most common in cool-season tall fescue, says John Haguewood, Quali-Pro’s Gulf Coast area manager. He adds that brown patch also can be found in St. Augustinegrass, centipedegrass and seashore paspalum warm-season grasses.

Brown patch tends to appear as roughly circular areas on the turf. The patches can range in size from 6 inches to several feet in diameter, and they vary in color — including yellow, tan, orange and brown — depending on the grass species, weather conditions and prior turf management.

Lane Tredway, technical service manager for Syngenta, says brown patch may be confused with gray leaf spot and Pythium blight and can develop at the same time.

Gray leaf spot appears as gray and fuzzy leaf spots that are oval or round, and Pythium appears dark brown or black and greasy. Tredway says with brown patch, irregularly shaped brown patch lesions appear on each individual leaf, which can range from tan to brown in color, with a thin dark brown border and a dry, desiccated texture.

Brown patch thrives in warm and humid conditions, and the fungus can become active whenever nighttime temps are above 60 degrees. The disease is strongest during May through September, though Tredway notes that he’s seen active brown patch during all months of the year except for January. “I always like to say that brown patch doesn’t have a calendar,” he says.

Photo: Lane Tredway

Brown patch can be identified by its irregularly shaped leaf spots and dry desiccated texture. Photo: Lane Tredway

Controlling the problem

“Understand the site and the historical opportunities, that’s your starting point,” says Rick Fletcher, technical services manager for Nufarm. “If you’ve got a plan for treating those diseases, that plan should include irrigation, thatch controls and core aeration.”

Brown patch thrives during periods of high humidity or 10 hours or more of leaf wetness. Fletcher recommends not irrigating late in the day, since leaving grass wet all night can help promote the growth of brown patch fungus.

Fertilization is also a key component of brown patch control, Tredway says. He recommends that small amounts of nitrogen (0.25 pound of nitrogen per 1,000 square feet) be applied over the summer months.

As for chemical control, a variety of active ingredients including azoxystrobin, propiconazole, thiophanate-methyl, tebuconazole, flutolonil and polyoxins are effective on brown patch in rotation or in combination.

Both Tredway and Haguewood recommend introducing brown-patch-resistant varieties of tall fescue into lawns.

Fletcher says that over time, if a lawn care company is aerating, overseeding and thickening up a stand or doing annual fraze mowing or dethatching, it can slowly introduce resistant cultivars into the turf.

Fairway Green tries to get ahead of its brown patch problems with a proactive strategy, according to Herrmann.

“The best way to control injury and damage brown patch is to control on a preventive basis,” he says. “Get out there before the disease gets active and protect the turf with a fungicide.”

Fairway Green uses various fungicide brands and modes of action that provide coverage from 17 to 28 days. The company also provides a leave-behind flyer to educate customers on brown patch and the treatment process.

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