Text adapted from Turfgrass Pest Management Manual: A Guide to Major Turfgrass Pests and Turfgrasses
North Carolina Cooperative Extension Service

CAUSE: Specific cause unknown; however, nematodes, low potassium, high phosphorus levels, high nitrogen fertilization, ground pearls, high pH, fairy rings, drought, excessive thatch, traffic, heavy shade, herbicide injury, and several diseases have been associated with the problem.

HOSTS: Centipedegrass

SYMPTOMS: Small circular dead areas appear in lawns after several years of good turf. Areas do not green up in the spring or begin to die in late spring or during drought stress periods in the summer. Grass at the edge of affected areas may be yellow (chlorotic) and may eventually wilt and die. Nematode damage first appears as weak areas that are invaded by weeds. Fairy rings appear as circular green or dead areas that continue to enlarge for several years. Ground pearls appear as circular dead areas with only weeds growing in the center.

CONTROL: Centipedegrass usually produces a better turf over a number of years if the soil pH is maintained between 5 and 5.5 and low levels of nitrogen fertilizer (not more than one pound per 1,000 square feet per year) are applied. The use of a high potassium fertilizer in sandy soils and low phosphorus fertilizer in high phosphorus soils may help prevent centipede decline. Lowering of a high pH with sulfur materials will reduce chlorosis from iron deficiency. Chlorosis can be temporarily corrected by applying ferrous sulfate or iron chelate. Soil test results can provide information needed to select the above treatments. Apply enough water about once a week during dry weather to wet the soil at least 6 inches deep to avoid drought stress. Mow centipedegrass at 1 inch height as needed since it accumulates less thatch and survives the winter better than at taller heights. Do not "burn off" centipedegrass in the winter because entire plants may be killed and recovery may be slow in the spring.
Rototilling and replanting with healthy sprigs have resulted in the best recovery and eliminated the problem in some cases. Use nematode assays to determine if nematodes are a problem. Good management practices will help overcome the effect of some nematodes.
Soft and spongy lawns may need to be dethatched or power raked to remove debris. Lowering the mowing height in early spring and collecting the debris may also help.
See section on fairy rings and ground pearls for discussion of these pests. Planting a more tolerant grass species should be considered when these two pests become major and recurring problems.

Figure 2. -- "Fairy ring on centipedegrass", North Carolina Cooperative Entension Service