Q: I noticed brown sap oozing from my three-year-old dwarf peach tree. An arborist told me this is caused by peach borers. I sprayed insecticide but recently I have noticed a few areas around small branches where the sap is coming out again. How do I save this tree?
A: In my experience, peach tree borers are rarely the cause of sap coming out of a peach trunk. If you notice the sap oozing more than 12 inches from the bottom of the tree, it is almost certainly not borer damage. Typically the sap comes from a bark canker. The canker, in turn, comes from environmental or mechanical stress on the tree. Poor root growth, drought, or kids banging on the tree with a stick all could cause cankers. Be sure to mulch your tree, water during dry times, and consider sprinkling a pint of garden lime around the tree to raise the soil pH.