Text adapted from Turfgrass Pest Management: A Guide to Major Turfgrass Pests in Oklahoma. Oklahoma Cooperative Extension Service.

CAUSE: The most important disease of bermudagrass in Oklahoma is spring dead spot. The cause of this disease is unknown at this time (two fungi, Leptosphaeria narmari and Leptosphaeria korrae have been identified as the causal organisms for this disease in Australia and California).

HOSTS: Bermudagrass.

SYMPTOMS: Circular dead spots first appear in spring as bermudagrass resumes growth from winter dormancy. These dead areas are clearly visible in spring and are often confused with winter kill (Figure 1). The spots appear in many of the same places and expand for 3 to 4 years. After the second or third year, the disease often appears as rings of dead bermudagrass, and may disappear after 3 or 4 more years.
The roots and stolons of bermudagrass in affected areas are severely rotted. Regrowth of grass into the dead spots is generally slow, possibly taking the entire growing season to fill in. In some areas, the dead spots remain barren or fill with weeds. When the grass recolonizes the affected areas, it remains stunted.

DISEASE CYCLE: The causal fungi appear to grow most actively during the autumn and spring when temperatures are cool and the soil is moist. This is also when bermudagrass root growth is extremely slow; thus, the pathogen has a competitive advantage over the bermudagrass.

FACTORS FAVORING DISEASE DEVELOPMENT: Spring dead spot is a disease of mature bermudagrass that is intensively managed. The disease is less severe or absent on bermudagrass maintained at low levels of fertility. Heavy applications of nitrogen in late summer stimulate lush, succulent growth that is very susceptible to spring dead spot. Excess thatch accumulation also favors disease development. Cold weather is also a factor since the disease seems to be more severe following extremely cold winters.

CONTROL: Fertilize to meet the nutritional needs of the bermudagrass, but do not apply high rates of nitrogen after late August to prevent lush, succulent growth late in the season. Prevention of thatch accumulation and improving soil drainage through aeration will also help minimize disease problems. Bermudagrass cultivars that have high levels of winter hardiness appear to be less affected by spring dead spot.
Many fungicides have been tested for effectiveness against spring dead spot. The most promising fungicides should be applied in autumn (mid-September to mid-October) to areas that had the disease the previous spring.