One of my lemon trees has been producing new flushes of growth every month or so. The problem is, when the leaves are approximately half way through their development, they get yellow and black spots on them, which looks like a fungal attack. I have been spraying the tree with copper to try to eliminate it, but it keeps happening. It doesnt seem to kill the leaves, but they end up stunted or deformed. Also, where the tree recently dropped some leaves (a month or two ago) The tree has developed open "wounds" in a few places, that ooze a clear sappy liquid, which harden almost like mini icicles on the tree. If i remove them, it oozes more and then hardens. The wounds do not seem to be healing at all, and i have no idea how they developed. I'll post pictures later today. Any thoughts on what the problem is, and how to treat it?
Maybe some type of fungal infection. Copper can become toxic if used to often. Also check your soil, may be the start of root rot from keeping it too wet.
I had two trees that developed the oozing sap as described. Sadly, neither of them survived. The problem may have been gummosis. The roots seemed healthy on the one tree that I checked.