ALABAMA A&M and AUBURN UNIVERSITIES

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contact Donna Reynolds, Extension Assistant Editor

CONTROLLING SPRING DEAD SPOT AND BERMUDAGRASS DECLINE

Auburn, March 12---Spring dead spot (SDS) is a damaging disease of bermudagrass lawns, golf tees and greens. Although the disease is most common in the northern half of Alabama, it may be seen statewide after an unusually cold, harsh winter. A similar patch disease occurs on zoysiagrass.

The development of both diseases is closely tied to turf management practices, says Dr. Austin Hagan, Extension plant pathologist with the Alabama Cooperative Extension System. Spring dead spot occurs most often on over-managed 3- to 6-year-old turf. Excessive nitrogen fertilizing, potash deficiency, sharp increases in soil pH, and thatch accumulation contributes to the development of SDS.

Low maintenance bermudagrass lawns seldom have trouble with SDS. However, low-mowing heights, poor drainage, thatch accumulation and high soil organic matter content have been linked with bermudagrass decline on golf greens and tees.

Symptoms of SDS-damaged turf include arc-shaped to circular patches of bleached, dead turf ranging from a few inches to several feet in diameter. Patches of diseased turf often appear in the same areas year after year.

Bermudagrass decline first appears as irregular patchesof yellow turf up to several feet in diameter in summer. Extension thinning develops as diseased grass turns yellow, withers and dies. Patches of bare ground may be seen on badly damaged greens.

Recovery from SDS-damaged turf is slow says Hagan. The unsightly patches become less noticeable 2 to 3 months after spring green up. In drier, cooler areas, the circular patches of dead turf may persist from year to year. On turf damaged by bermudagrass decline, improvement in turf quality may be seen in the fall or early spring, but symptoms rarely disappear.

Management practices that promote root growth should help reduce the risk of disease outbreaks and speed recovery of damaged turf. To further reduce the risk, fertilize with nitrogen lightly but frequently to maintain moderate turf growth throughout the growing season. Continued use of slow- release forms of organic or inorganic fertilizers also may reduce the risk of SDS and similar patch diseases.

A near neutral to slightly alkaline soil pH may increase severity of SDS on bermudagrass. Maintain soil pH at 5.8 to 6.2. On high-risk turf, lime lightly each year to maintain a recommended soil pH. Use acid-forming fertilizers on sites with near neutral to alkaline (7.0+) pH. Apply iron, manganese and other micronutrients monthly, and apply gypsum periodically on SDA and bermudagrass decline-turfs.

For more information on maintaining and fertilizing bermudagrass and zoysiagrass lawns, visit your County Extension office and ask for Extension circular ANR-239, "Lawn Maintenance in Alabama."