Almost all turf diseases are caused by some form of soil dwelling fungi.  For the most part, these fungi are held in check by the beneficial fungi and other microorganisms in the soil. But every now and then they get the upper hand and can do real damage to your lawn. Brown patch is an example of what occurs when the fungi grows out of control. The fungi in question is called Rhizoctonia, and it can survive dormant in the soil for years.

Brown patch seems to show itself in most all species of grasses and seems to thrive on a number of factors such as:

• High temperatures with high humidity
• Higher than normal level of nitrogen in the soil
• Over watering in such a manner that the grass stays wet for extended periods of time

Typically, here in the Raleigh/Cary area of NC, it beings to occur in early summer when temperatures and humidity begin to climb. There seems to be a higher number of incidents of brown patch in yards that have irrigation systems (most likely due to over watering). The patches themselves are irregular circular areas up to several feet in diameter with a brownish grey appearance.

For the most part, brown patch will recede on it’s own with proper landscaping management and nitrogen control. In extreme situations or situations on high value greenery like golf courses or baseball fields, it can be treated with fungicides. We highly recommend that you allow a landscaping professional to evaluate and perform anti-fungal treatments instead of trying to do it yourself.

Excessive use of an anti-fungal will kill both the good and bad fungi, which throws the soil severely out of balance. In some cases, this allows the brown patch to occur again even more seriously the following year as the beneficial fungi is no longer present to help keep the Rhizoctonia fungi in check.