We have a spring dead spot ( SDS ) problem on bermudagrass . The SDS first appeared last year , and is twice as bad this year . I was trying to find a cheap and quick way to help the current problem , and was wondering if cutting out the patches and replacing them with sod would be a good idea . Is this something we can cure with chemicals , which seem pretty expensive ? What is my best option for the money ?

Q & A WITH DR . GRADY MILLER

I consulted with NC State ’ s turfgrass pathologist Lee Butler . The comments that follow are based on our combined experiences .

The causal fungus of SDS doesn ’ t spread far from the original patch . It resides in the thatch layer , typically two to four inches deep . It spreads through hyphal growth and spores , both of which do not move far from the original patch , explaining why SDS patches reappear in the same spots each year . It can be spread in the immediate localized area when soil is disturbed through aerification , vertical mowing , etc . The disease typically takes three to five years to become established in a new bermudagrass stand and , if unmanaged , often becomes more severe as the turfgrass matures .

Cutting out the damaged areas in the spring and replacing them with a large turfgrass plug or sod may work if enough soil is removed around and below the necrotic spot . This would be a lot of work if there are more than a handful of infection sites . It will not help with new infection sites , so this may be a reoccurring need each spring for years . I have never known anyone to try this as a normal cultural practice , so this comment is based more on the known biology of the causal fungus .

Chemical control is highly effective against this disease . However , it may take a couple of years to really clean up the damage , and you will likely have to continue with applications every fall to maintain SDS-free fields . If you

If you choose to apply fungicides , you will need one to two well-timed fall applications to be effective , and those applications will need to be watered in immediately after spraying .

choose to apply fungicides , you will need one to two welltimed fall applications to be effective , and those applications will need to be watered in immediately after spraying to move the chemical to where the fungi reside in the thatch layer . So , treating for SDS requires a good irrigation system , or you will have to spray during a light rain event .

To answer your question about cost-effective options , let ’ s go back to the biology of the fungus . SDS is caused by three different species of the Ophiosphaerella fungus . The primary species we have in North Carolina is Ophiosphaerella korrae . Our turfgrass pathologists have had success in the past controlling this species through the use of calcium nitrate as a nitrogen source . They applied calcium nitrate at 1 pound of N per 1,000 square feet per month from May through August for a total of 4 pound of N . Within two years , they had completely suppressed SDS symptoms without using fungicides . On the other hand , O . herpotricha , the most common pathogen in Midwestern states , was suppressed by ammonium sulfate .

So , if you want to try something not fungiciderelated , selecting a nitrogen fertilizer source specific to your fungi / location would be one thing you could attempt . Or couple this with fungicide applications in the first year and reevaluate next spring . SDS is more severe in heavily compacted soils , so be sure to aerify those fields as much as you can to help relieve any highly compacted areas . SFM

Grady Miller , Ph . D . Professor and Extension Turf Specialist North Carolina State University

Questions ? Send them to Grady Miller at North Carolina State University , Box 7620 , Raleigh , NC 27695-7620 , or e-mail grady _ miller @ ncsu . edu

Or , send your question to Pamela Sherratt at 202 Kottman Hall , 2001 Coffey Road , Columbus , OH 43210 or sherratt . 1 @ osu . edu

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