Plum Tree problem I can't identify
I'm hoping someone out there can help me identify a problem w/ a plum tree in my yard. It has a significant area of the trunk which is very black and looks like it was burned, but I know wasn't. I was told it might be Black Knot disease, but the black area on my tree doesn't have any rough knots and bumpy areas characteristic of that disease, but is instead very smooth and very black. PLEASE HELP?!