Weather bringing brown patch to lawns

Published 12:00 am Friday, June 20, 2008

By Darrell Blackwelder
For the Salisbury Post
The last month our lawns have been on the steady road to recovery.
The unseasonably cool weather and welcome rains in April and May provided perfect growing conditions for fescue. Unfortunately, once the excessively high temperatures of summer finally arrived so did 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 enviornment for this disease.
Early symptoms are small circular brown patches of turf a foot in diameter. Small patches often melt 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.
Fescue lawns established less than one year can be severely damaged or completely eliminated by this disease. Seeding rates of more than 6 pounds of seeds per 1,000 square feet produces small, crowded seedlings with poor root systems that are also susceptible to brown patch.
Over-seeding with different fescue cultivars helps 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 soil pH of 6.0-6.5 to achieve maximum health and growth to ward off the fungus. Turf and ornamental fungicides such as Banner, Bayleton, Eagle and Heritage can be applied as a control for brown patch. Contracting a lawn care company to spray these may be in your best interest. However, 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. Unfortunately, many are over-irrigating now compounding the situation. Unusually cool, wet weather over the past few weeks has made this almost impossibility, 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. Call 704-216-8970.
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