How to prevent pests from damaging apple trees

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Q. My trees bore many damaged apples last year. What insect pest(s) are most likely involved and how can I prevent a repeat of the damage?

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A. Two main pests that target apples are coddling moth and apple maggot. You can tell which one you are dealing with by the nature of the damage.

Coddling moths emerge soon after apple blossom time to lay eggs on and near developing fruit. The eggs hatch into larvae that bore into the core of the small apples to feed there for around a month before crawling out to pupate and produce a second generation of egg-laying adults in July and August.

Apple maggot flies begin to emerge in early summer. The females pierce the fruit to lay eggs in July, August and September. The eggs hatch into larvae that make a maze of thin tunnels as they feed on the flesh.

One tunnel in and out of an apple core signifies coddling moth. Whole sections of browned flesh indicate apple maggot.

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Monitoring the trees carefully and removing fallen and suspect fruit is useful. Keeping trees compact with summer pruning makes monitoring manageable. Monitoring for coddling moth involves watching from the time the apples are marble size for entry holes. Remove and destroy suspect and fallen apples.

Larvae can be trapped as they move down the tree trunk to pupate. In early June, wrap a 20-cm wide band of corrugated cardboard around the trunk. Some of the larvae will stop to spin cocoons in the bands. Check every 10 days for cocoons and larvae to pick out. Replace with fresh bands in mid-July.

As with coddling moth, monitoring for and physical removal of suspect apples works well for apple maggot. Watch for fruit with tiny dimples where eggs have been inserted. Remove and destroy affected apples, along with all fallen fruit.

Both pests overwinter in the soil and leaf litter under and around the tree. Keeping the area under and around the tree scrupulously cleaned is helpful.

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