During the “dog days” of summer, we often see Bermuda and zoysia lawns with irregularly shaped brown or red colored areas that “look” dead. The respective areas turn from green to brown or red very quickly, with the adjacent green areas often looking normal. There are several reasons why this may occur, but I believe the most common reason is due to a condition sometimes referred to as “summer stress complex” by lawn care professionals, though specific diseases are sometimes the culprit.
Summer Stress Complex consist of a myriad of fungi that in unison, can damage turf tissue quickly. It’s most common when temperatures are high, the turf canopy becomes wet, but soil moisture is low.
When this condition occurs, watering the lawn appropriately is important, as a dry root system probably influenced establishment of the problem to begin with. Core aeration will often benefit the lawn significantly, as both water and oxygen movement into the soil is facilitated. And rather than applying fungicide, fertility should be stepped up to encourage regrowth and recovery.
Irregular brown areas establish very quickly
If a mower passes over affected area while pathogens are active, the pathogens may be transferred via mower wheels