Q. Each year when I prune my walnut tree in March it "weeps" quite badly. What am I doing wrong?

A. Walnuts, as well as maples and birches, should be pruned after they have leafed out. The leaves absorb the sap running up through the tree, and there is no loss of sap from the cut ends. While the loss of moisture is not too serious for the tree, it is unsightly when it occurs.