SALISBURY — The unseasonably cool weather and welcome rains in April and May provided perfect growing conditions for fescue. Unfortunately, once summer temperatures finally arrive, so do disease problems. Large brown circles have tainted cool season fescue lawns in our area with a vengeance. Brown patch is here.
Brown patch is a common turf disease caused by a soil-borne fungus Rhizoctonia solani. Recent weather patterns of rain and heavy cloud cover, along with temperatures above 80 degrees provide the perfect environment for this disease. Early symptoms are small, circular brown patches of turf a foot in diameter. Small patches often meld together and may engulf an entire lawn.
Turf fertilized with high rates of nitrogen fertilizer during late spring or early summer makes lush fescue susceptible to the disease. Tall fescue grown in partially shaded lawns with restricted air movement is more susceptible to brown patch because of higher humidity and more succulent growth.
Tall fescue should not be fertilized after the first of May, unless you are using ultra low rates with iron for a color effect. The recommended amount of nitrogen on tall fescue per year is 3-4 pounds per 1,000 square feet.
Seeding rates of more than 6 pounds of seeds per 1,000 square foot, produces small, crowded seedlings with poor root systems that are also susceptible to brown patch.
Over-seeding with different fescue cultivars will help reduce the rapid spread of the disease. Monocultures of fescue cultivars can be completely engulfed by the fungus.
Brown patch-infested lawns may need soil testing to determine if low pH is a contributing factor. A pH below 6.0 aggravates the spread of brown patch. Now is the time to have soils tested if fall renovation is in your plans. Soils must have a proper pH of 6.0-6.5 to achieve maximum health and growth to ward off the fungus. Turf and ornamental fungicides are necessary to control the fungus. There are some user-friendly granular fungicides available that may help.
According to plant pathologists at N.C. State University, the most important step of controlling brown patch is infrequent irrigation and regular mowing when the grass is dry. Unusually cool, wet weather over the past few weeks has made this almost impossible, hence the rapid outbreak of the disease. Avoid irrigation in the late evening or at night. Early morning irrigation helps prevent the spread of brown patch.
Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. Contact him at 704-216-8970.
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rowan.ces.ncsu.edu
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