WSU CAHNRS

Washington State University

Gardening in Washington State

Protect your apples from codling moth this season!

If you grow apples, the codling moth will come! The larva of this common pest, also known as “the worm in the apple,” directly impacts the eating quality of apples across the state of Washington. When left unmanaged in backyard trees, the codling moth can damage as much as 80 to 95 percent of the fruit—making it “wormy” and unfit to eat.

FIg 1
Figure 1) Codling moth is about 3/8 inch-long; one female moth will lay dozens of eggs. When eggs hatch, larvae bore directly to the fruit’s core. Photo Credits: Michael Bush, WSU Extension

Fig 2
Figure 2) Apple fruit with signs of codling moth infestation; look for the conspicuous piles of brown granular excrement plugging the entrance hole on the surface of the apple. Photo Credits: Michael Bush, WSU Extension

Washington homeowners must protect their apple or pear fruit from two, or sometimes three (in the warmer regions of the state) generations of codling moth each year. The adult moths fly during warm evenings, with peak activity in May, July, and late August. The best means of protecting backyard fruit trees from codling moth infestation is an integrated pest management (IPM) program utilizing several control strategies.

Management Strategies:

1) Plant your fruit trees on dwarfing or semi-dwarfing rootstocks.
2) Scout your fruit (weekly) from late May to apple harvest time for signs of codling moth larvae infestation. Pick off infested fruit and crush to kill larvae protected inside the fruit.
3) When the fruit is less than 1 inch in diameter (early to mid-May), individually bag each fruit left on the tree. Standard paper bags or commercially available apple bags can be used.

Fig 3
Figure 3) Backyard apple tree with commercially available apple bags.

4) If pesticides are used, they must be applied during adult moth activity so that the pesticide covers the fruit surface before the eggs hatch. Pesticide sprays should start 17 to 21 days after full bloom (about 10 days after most of the flower petals drop from the tree) to target the newly hatched larvae before they bore into the fruit. For a list of effective pesticides used to manage codling moth, homeowners can contact their local WSU Extension office or visit the WSU Hortsense website.

For more information, see Codling Moth and Your Backyard Fruit Tree.

Submitted by: Michael Bush & Marianne Ophardt, May 23, 2014

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2 comments on “Protect your apples from codling moth this season!”

  1. Fred Staloch said on January 24, 2015:

    In this section where the apple trees are bagged, the caption are switched around.

    Thanks,

    Fred Staloch

  2. Mike Bush said on February 2, 2015:

    Fred (MG volunteer- Yakima) and I spoke during our last Master Gardener Training Class. Just a little confusion regarding the fact that in FS120E, Figure 5 Fred is standing next to a “Bonsai Fruit Tree” that he prunes to a height of 8 feet tall (not to 10 to 12 feet as reported in the caption).

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