Answer: If you have tried absolutely everything, including repeated chemical controls, I think it is time to have the turf problem looked at by the plant pathologists at Coos County Cooperative Extension office (629A Main Street, Lancaster, NH 03584-9612, Phone: 603-788-4961, Fax: 603-788-3629).
You may be able to mail in a sample for diagnosis. Once the problem has been positively identified you will be given suggestions for treatment/control. Best wishes with your lawn!
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