What is it? I searched some but couldn't find any photos close up enough to match it. It's on a short stub where I had cut off a small branch a few weeks ago.

http://i64.tinypic.com/23l0hi0.jpg

Should I spray, if anything? I don't see it anywhere else in the tree. I seldom spray any plants and have little troubles. When I do spray, first I try laundry soap in water which works most of the time.