Our oak tree that is a little more than 20 years old leafed out healthy in the spring. Then the leaves started turning brown and curling until almost the entire tree is brown leaves. Does this mean we are losing our tree? Should we wait and see if it makes it through the winter and the leaves come out healthy next year? Please advise. Thank you. PS I tried to send a photo of the tree, but the file was too large. Please let me know if you need a different photo.