Question
Sir, I have a large Pen Oak I planted as a sapling. It is now 30 years old. A few years ago I noticed the leaves on one side at the bottom turning brown and spotty, about a month after it had leaved out in the spring. Each year the same thing occurs only the effected area gets bigger. This area now covers the entire east side of the tree and has started down from the top on the other side. Each year it leaves out normal and then starts turning brown about a month later. Do you know what this is and is there a treatment? Also,will this spread to a large Pen Oak right next to it?  I live in north east Olahoma ( Tulsa ).  Thanks, LG

Answer
If it is on one side of the tree it sounds like the problem is environmental. If it is next to the road or sidewalk then it could be heat reflecting from the road or walk. Is anything being sprayed on that side of the tree--utilities spraying herbicide on that side? Has there been any digging on that side causing root damage-this will show up as foliage damage on that side.?  If it was a fungi disease either a root problem the foliage would be effected on all sides of the tree. Does not sound like a fungi and if not then it will not spread to other trees.
I would call the Okla. State Forestry agency and ask one of their Foresters to come take a look. You also might call the Tulsa City I think they have a Forester working as an Urban Forester.  Mike Perkins Parks & Recreation Forester City of Tulsa, This is the only phone number I could find 918) 596-1929 I think it is the number for the Tree Advisory Committee but they will know how to contact the City Forester.