The Q&A Archives: Spray Apple Tree for Worms

Question: I have a mature gravenstein apple tree. We have apples every other year, but no matter what spray we use, they always seem to have worms. What spray should I be using and when? Thanks in advance for your help. Terry

Answer: The fruits of apple trees are often ruined by Coddling Moth larvae and Apple Maggot. Coddling moth larvae are usually found in the core area of the apple. The adult lays eggs inside apple blossoms. When the fruit forms, the egg hatches into a worm-like larvae. It's difficult to keep the moths from accessing the open blossoms. Apple Maggot is the immature form of an adult fly. The fly lays eggs just under the skin of the developing apple. When the eggs hatch, the larvae tunnel throughout the flesh of the apple, leaving rust-colored frass (bug poop). When it's time to leave the apple, the larvae digs an exit hole, spins a web, and pupates in the soil below the tree, where it emerges as an adult some months later. Control of both these pests is difficult. There are some pheromone traps (sex attractant) available through mail order companies that you can hang in your trees. Many gardeners have success in trapping Apple Maggots by using red rubber balls, or painting styrofoam balls red, coating either with sticky 'Tanglefoot', and hanging them in the tree. The flies are attracted to the red spheres and try to lay their eggs. They'll be hopelessly stuck if they land. Be sure to pick up and bury any infested or fallen fruit from the tree to prevent a population explosion of either pest. Your cooperative extension office may have other control ideas.

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