QuestionI have a very old purple plum tree and just discovered some (what we believe to be) American Plum Borers living inside the tree. Is there any way to save the tree? I've been to two nurseries and no one can give me an answer as to what to do.
AnswerThere is a newer systemic insecticide called Merit that works well on borers. It is sprayed on the wound are and adjacent trunk and is absorbed into the bark and wood killing the insect. I would spray now and again in 30 days. If you still see fresh signs of insect activity spray a third time but I feel the two sprays will solve the problem.
American plum borers tend to attack trees that are weakened either by wounds to the trunk or under stress. I would recommend that the tree be fertilized with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree under the foliage line and watered in good. Do this now and again in early fall. This will strengthen the trees root system and increase the overall health of the tree.
