Question: What is the waxy sap I see on the trunk of my purple plum and flowering peach down near the soil line?

Answer: That’s work of the peach tree borer. Spray with a borer preventive the last week of August to prevent its invasion. It’s extremely difficult to cure an established outbreak because the worms are in their tunnels, safely behind the congealed sap. Hopefully, the damage isn’t too severe already.