Brown Patch is the most common disease of lawn grasses in Tennessee. It is a common problem of turf-type tall fescue lawns in early Summer. Patches six inches to three feet develop during hot, humid weather. Characteristic straw or tan colored lesions with dark margins on leaf blades and the early morning “smoke ring” of actively growing mycelium at patch borders are easily recognized symptoms of this disease.

Use fertilizers with slow release nitrogen. Do not fertilize your fescue lawn after April 30th, as high nitrogen levels make fescue more susceptible to this disease. Do not irrigate at night. Irrigate early in the day so the grass canopy can dry before nightfall. Overseed areas damaged by brown patch in September to mid-October to thicken the stand of grass.

Lawn fungicides can be used to protect grass from this disease, however, in many cases tall fescue recovers with the advent of cooler fall weather without fungicidal treatment. If using a lawn fungicide, apply the fungicide in areas where brown patch has occurred in the past, prior to symptom development. Brown patch usually appears in tall fescue lawns when relative humidity is high, and temperatures reach 65-70 F at night and >85 F during the day. There are several fungicides labeled for brown patch (and other turfgrass diseases) control available to homeowners. Most work best when applied at the first sign of symptoms or even before symptoms appear but conditions favoring brown patch development occur. Most fungicides will require multiple applications to provide season-long protection.

Tall fescue is susceptible to other diseases, but brown patch is the most common.