Brown Patch of Tall Fescue
Brown Patch normally occurs in midsummer and results in the formation of unsightly blighted patches of turf. The disease may first appear as round circular patches that range in size from a few inches to several feet. The patches may coalesce to form a larger area. Often this disease is mistaken for drought stress as infected areas have a similar appearance.
Under close examination of the blades irregular spots may be noticed that is bordered by a dark margin. Brown Patch development is very rapid, appearing within 24 to 36 hours after infection.
The development of Brown Patch is favored by nighttime temperatures above 70 degrees and a high relative humidity. Tall fescue under high management, especially high nitrogen fertilization is more susceptible to severe damage.
No tall fescue cultivar has good resistance to Brown Patch, but Adventure, Arid, Falcon, Finelawn I, Jaguar, Olympic and Trident have shown less damage.
Brown Patch occurs less frequently when the nitrogen level is adequate or low and the phosphorus and potassium levels are good. Do not over fertilize and apply a majority of the nitrogen in the fall months. Avoid irrigation in the late afternoon or evenings to reduce the spread.
Brown Patch can be suppressed by fungicide applications. Such products as Bayleton or chlorothalonil applied at monthly intervals from June through August can reduce the problem. In mild cases the grass will recover in the fall under favorable temperatures and moisture and therefore treatments may not be needed.
For complete information refer to the following K-State link: Rhizoctonia Brown Patch of Tall Fescue.