Brownpatch
Lawn Disease

Identification: When brownpatch first appears, it looks like small, circular patches of the grass are water-soaked. This dark grass will soon wilt and turn brown. As it progresses, it forms an ever widening circle. In warm season lawns, the grass inside the circle has leaves that are easily pulled and, after time, the grass on the inside of the circle will begin to re-grow, leaving a ring of brown. In cool season grasses, the leaves of the grass will wilt but will remain upright. Also, there is often a dark, grayish-black ring of wilted grass around the affected area in the early morning.

Cause: This disease develops most rapidly when temperatures are around 75-85 degrees and there is plenty of moisture. This means that it is more likely to affect lawns sometime in the fall, especially since temperatures of 90 degrees and higher generally stop fungal activity. High levels of nitrogen in the soil can also increase the severity of the disease.

Prevention:

• Aerate your lawn often
• If possible, reduce the amount of shade
• Follow a schedule when fertilizing so you don't add too much nitrogen
• Water early in the morning and avoid over-watering
• Remove grass clippings when the disease is active
• Use fungicides as a preventative measure when conditions favor an outbreak

Treatment: Prevention is the best way to avoid damage, but, after the lawn is already infected by brownpatch, treatment with fungicides will help the grass rid itself of the disease and recover. Some of the possible fungicides used to treat this disease are benomyl and chlorothalonil.

Grass types susceptible: While many grasses can be affected by this disease, the ones in particular danger include bluegrass, carpet grass, centipede grass, fescue, and St. Augustine.