Problems on Centipedegrass

Turfgrass Disease Information Note 1 (TDIN-001)

Henry C. Wetzel III, Extension Plant Pathologist

Centipede decline is a name used to describe the most common problems observed on centipedegrass. These include dollar spot, large patch, fairy rings, nematodes, ground pearls and nutritional problems.

Dollar spot is a disease that is often seen on centipedegrass during the summer. The symptoms of this disease are light brown spots 2 to 4 inches in diameter. It does not appear to cause serious damage. Centipedegrass that is declining because of other factors may have more dollar spot than nearby healthy grass. Large patch caused by Rhizoctonia solani AG2-2LP has been identified on centipedegrass during wet weather in the spring, summer and fall. The symptoms in cool, wet weather are usually large circular patches of thin grass, however, early symptoms may be circular yellow patches. The grass may continue to decline in the affected patches, especially in dry weather, for a long time after the disease activity has stopped. Some fungicides may help control these diseases, including Banner Maxx, Bayleton, Eagle, Prostar or Heritage applied in the early fall should provide acceptable control the following spring.

Fairy rings have been shown to be the cause of some centipede decline problems. Fairy ring symptoms are large circular dead spots, dead rings, or green rings (3 to 20 feet in diameter) that enlarge for several years. Mushrooms of the fungi that cause this disease may be present at the edge of the rings or throughout the circles sometime during the year. Mushrooms may not develop for several years and suddenly appear following a weather pattern that induces mushroom development. Effective treatments are not known for fairy rings in lawns, however, rototilling the soil and replanting healthy grass has eliminate the problem in some cases.

Nematodes have been associated with the decline in sandy soils in some cases. The sting nematode has been shown to cause very serious damage on centipedegrass in sandy soils in southeastern North Carolina. Centipedegrass affected by this nematode will become thin and even die during hot-dry weather. The importance of the ring nematode which occurs frequently in centipedegrass lawns is not known. Damage from large numbers of this nematode has not been observed in many test plots established in the state. Since no nematicides are currently labeled for use in residential lawns, management practices will have to be used to help overcome damage from nematodes. A good management program that includes irrigation when needed can be used to overcome the effect of the ring nematode, but not the sting nematode. Another grass such as bermudagrass or bahiagrass may be an alternative to use in centipede lawns with high levels of sting nematodes. Incorporation of organic matter in the soil may help overcome nematode damage; however, care must be taken to avoid too much nitrogen being released for centipedegrass.

Ground pearls which are small scale insects that attack the roots of centipedegrass may cause circular dead areas that resemble fairy ring. The spots enlarge each year and only weeds grow in the spots. Ground pearls are identified by the presence of small pearl-like bodies on the roots or in the soil. The pink adult stage that crawls is present during early summer. A control is not know for the ground pearls. Other types of grass, such as bermudagrass or bahiagrass, appear to be less sensitive to ground pearls and should be considered for lawns with severe ground pearl problems.

Nutritional factors, including low potassium levels in sandy soils, high phosphorus levels, the use of too much nitrogen fertilizer, and low or high soil pH (5.5 is best) have been associated with the problem. High soil pH will cause centipedegrass to turn bright yellow, especially in the spring, due to iron deficiency (iron chlorosis). High phosphorus levels can increase iron chlorosis since it can replace iron in the plant. The use of fertilizers high in phosphorus may contribute to the decline of centipedegrass. Soil test results should be used to correct these problems and to determine fertilizer requirements.

Improper mowing and fertilization have been indicated as factors in experimental plots where centipede decline developed. More decline was observed in the spring where the grass was mowed at 2 inches than at 1 inch and where high nitrogen rates (2 pounds per 1,000 sq. ft.) were used. More thatch accumulated at the higher mowing height with high nitrogen and caused the stolons to be above the soil. These stolons are more susceptible to damage by cold weather. More centipede decline usually occurs in the spring and summer following very cold winters or following winters with unusually warm weather and then late cold periods. Excess nitrogen increases the thatch and reduces cold and drought tolerance of centipedegrass. Usually not more than 1 pound of nitrogen per 1000 sq. ft. per year is needed on sandy soils. The use of fertilizers that are high in potassium and low in nitrogen may help to reduce stress during the summer and winter. This grass has grown well on clay soils without any fertilization for many years. Centipedegrass has a naturally light green color when managed properly. If a darker green turf is desired in the lawn, another type of grass such as bermudagrass or zoysiagrass should be considered.

Centipedegrass is not very drought tolerant and may be damaged during very dry weather. Irrigation when needed will help reduce damage from drought stress. Localized dry spots of soil that are hydrophobic (difficult to wet) have been associated with declining patches of centipedegrass. The soil in these patches may be powder-dry even after rain or irrigation. Loosening of the soil and heavy irrigation is needed to wet the soil in these spots.

The use of certain herbicides (as sprays or in fertilizers) has been associated with the decline problem. Centipedegrass is very sensitive to some herbicides and recommended herbicides should be used according to label directions for centipedegrass. Damage has been observed where fertilizers containing some types of herbicides have been applied at rates suggested for other types of turfgrasses. In addition to herbicide damage, too much nitrogen is often applied from the herbicide plus fertilizer products for centipedegrass and causes problems discussed above. Once a good stand of centipedegrass is established, weeds usually are not a problem because of the allelopathic activities that centipedegrass has against other plants. Therefore, herbicides should not be needed each year on centipedegrass if it is managed properly.

Centipedegrass is not very shade-tolerant and does not grow well under trees with dense foliage. Root competition from nearby trees may increase drought stress and sometimes causes fairy ring-like symptoms. The landscape should be redesigned to use mulch or shade-tolerant plants in these areas if the trees cannot be removed.

Centipede decline may be caused by a number of different factors and accurate records of previous treatment may be useful in diagnosing the problem. Centipedegrass will usually spread over dead areas more rapidly if the old grass is removed and the soil loosened. New sprigs should be planted in the areas in late spring or early summer for faster recovery.

Additional information on the management of centipedegrass and diseases is given in the N.C. Agricultural Extension Publications AG-381, "Centipedegrass Lawn Maintenance Calendar", and AG-360, "Diseases of Warm - Season Grasses." Your local Cooperative Extension Agent can provide these publications and additional information.

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Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data. All recommendations for pesticide use were legal at the time of publication, but the status of registration and use patterns are subject to change by actions of state and federal regulatory agencies. 03/93/1000

Published by North Carolina Cooperative Extension Service Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Reformatted Dec. 2000 by avlemay