Question
We live in Maryland and have a large maple tree in our backyard that we think is about 20 years old. Last summer, it started oozing a liquid from it's trunk. This ooze has a strong sour smell to it. This year the tree didn't sprout many leaves - about half of the branches are bare. We don't want to lose this tree as it provides a great deal of shade. What could be wrong with it & is there anything we can do to save it?

Answer
Thsi is a disease called slime flux or wetwood. It is caused by a bacteria that enters a wound and will build up pressure causing the oozing of the sap. The foul smell attracts insects. It generally is not a problem for the overall health of the tree. But maybe a systhon for other problems. I would suggest you contact the Maryland State Foresrty agency and ask for assistance in ID the problem on the ground. Here is the web site for contact information you can ask them for the Forest Health person or a Forester. http://www.ento.psu.edu/extension/factsheets/gallsOnOak.htm