Spring Dead Spot

The below was taken from a UGA Cooperative Extension Service Publication.  The entire publication can be found on UGA’s publication website.

Identification and Control of Spring Dead Spot in Georgia

Spring dead spot (SDS) is a persistent and destructive disease of bermudagrass in Georgia. The disease is particularly prevalent and damaging in north Georgia, especially in the Piedmont region. However, SDS can be observed throughout the state after harsh winters and in areas where bermudagrass has been exposed to freezing temperatures for extended periods of time. The disease has also been observed in zoysiagrass, although less frequently.

Symptoms

As turfgrass “greens up,” well-defined circular patches of dead, bleached-out grass are noticeable in affected areas (Figure 1). Recovery from the disease is slow. Because the turfgrass in affected patches is dead, the primary means of recovery occurs by spread of stolons into the patch. Because recovery is dependent on lateral infill of surrounding bermudagrass, symptoms can remain visible well into the growing season. If not managed properly, these patches may reappear in the same location the following spring along with weed species that may invade the voids (Figure 3). Patches can get larger year after year.

 

SDS

 

Spring dead spot symptoms. Multiple circular patches of dead, bleached grass are evident in the spring. Grass at the center of the patches is completely deteriorated and usually colonized by weeds. Sharp edges between dead and healthy grass are observed once turfgrass greens up in spring. (Photos Alfredo Martinez)

 

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Disease Management

Complete control of SDS in a single growing season is uncommon. It typically takes two to four years of proper cultural management and fungicide applications before acceptable control can be achieved. This has led to SDS becoming one of the more difficult diseases for growers to manage on an annual basis.

Cultural practices that improve the cold-hardiness of bermudagrass can be particularly effective for managing SDS. Proper use of nitrogen fertilizers is important because high nitrogen levels can reduce the winter hardiness of bermudagrass. It is recommended that no more than ½ pound of nitrogen per 1,000 ft2 be applied after mid-September. Potassium applications in the fall (September or October) that total 1 pound of K2O per 1,000 ft2 can be helpful in improving the winter hardiness of bermudagrass and thus reduce SDS severity. Potassium applications should be applied based on soil test results.

A neutral to slightly alkaline soil pH has been linked to increased SDS severity. Maintain soil pH at 5.8 to 6.2. Use acid-forming fertilizers on sites with near neutral to alkaline pH. Apply iron, manganese and other micronutrients based on soil test results. Any soil condition that reduces bermudagrass root growth such as compaction, excessive thatch (> ½ in) and poor drainage can also increase the severity of SDS. Core aeration and other practices that reduce soil compaction and encourage the production of new roots can be helpful in managing this disease.

Chemical Control

Timing, selection and application of fungicides are important for preventative management of SDS. Research has shown that one application of fungicide in the fall when soil temperatures are between 60° and 80° F provides the best control of SDS.

Those who have seen good results say they spray preventative fungicides that target SDS each year and have been doing so for several years. Therefore, it is important to keep in mind that controlling SDS takes time and usually cannot be obtained in a single season.

Summary

Spring dead spot continues to be a major problem for turfgrass managers in Georgia. It is one of the more difficult diseases to manage because acceptable control is usually not attained in a single season. Soil conditioning and proper nitrogen and potassium fertilization are important cultural practices that can help reduce SDS. If acceptable control is not achieved with cultural practices, one or two fungicide applications in the fall may be necessary.