Pacific Northwest Gardening: Aspen issues, 1 by bonehead

bonehead wrote:
I have a fair sized grove of quaking aspen on the north side of our property. The leaves of the aspen and everything below them are coated with a sticky substance on the top side only. It's as if something has been sprayed on them. No noticeable bugs or damage to the leaves. No substance on the underside of the leaves. I don't use chemicals. The area is far away from the road and neighbor, so overspray is not likely. I've looked online and can't find anything. Here's a photo that kind of shows the sticky pattern. Any ideas?