My father in law has an oak tree, and a horse chestnut in his yard. There is a ring of brown grass about 5 feet beyond the drip line of each. It's about 6 inches wide. Numerous pine trees don't have this problem. All of the trees are between 20 and 30 feet tall, planted approximately 15 years ago. I'm assuming that is where the tree roots might end, but I've never seen this with any other tree. All the trees on the propery look fine. The dirt is heavy clay, if that matters. Any idea's on how to fix the ring of dead grass? THanks Matt Trahan <matttrahan@ecsu.campus.mci.net> or <garden@juno.com> USDA zone 8, AHS heat zone 7, Sunset zone 31, northeastern N.C.