A reader wrote to us recently about worms in her plum trees. She has three plum trees that have been attacked by some type of worm, and she is understandably keen to eliminate the problem. To get rid of the plum tree worms, she used some type of pesticide that failed to work. First we must attempt to figure out what type of worm she is dealing with (if it is a worm), and this is harder than you might think.