Thanks for your question. It's good that you are trying to verify the problem before attempting to apply a chemical fix.
You have a couple of options to verify if you have brown patch. Locally, you can either take a sample to the Norfolk VCE [757-683-2816] office on Southampton Avenue or the Hampton Roads AREC [757-363-3900] on Diamond Springs Road in Virginia Beach. I would call first to see when they accept samples and how big of a sample they would like.
From a treatment standpoint, if brown patch is the issue keep in mind that it is a cosmetic disease that usually only effects the leaf blades. When the weather begins to cool done, tall fescue suffering from brown patch usually bounces back with new green growth. Fungicides can stop the disease from spreading, but can sometimes do more harm than good by killing beneficial soil fungi. However, when suffering from heat stress and/or drought, this can result in plant death, and stopping the spread of the disease would be the greater consideration. Tall fescue is prone to brown patch. Fertilizing in the spring and/or summer can contribute to both the likelihood and severity of the disease.
Thank you very much for your timely and informative reply.