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Plum curculio

Conotrachelus nenuphar

Author: Esther McGinnis

Symptoms

  • Plum curculio is a mottled brown weevil with a curved snout that causes both feeding and egg-laying damage in apples.
  • Adult plum curculios usually appear at the time that apple trees bloom.
  • Feeding damage appears as small, round holes.
  • Adults puncture the apple skin to lay eggs and create tan, fan-shaped scars.
  • Larvae cannot develop in the expanding apple flesh if the apple remains attached to the tree.
  • Plum curculios can cause premature apple drop and will continue to develop and feed in the fallen apple that is beginning to rot.
  • Plum curculios cause more damage in plums, apricots and tart cherries.

Figure 1 Plum Curculio
Figure 1
. Adult plum curculio with curved snout. (E. Levine, The Ohio State University, Bugwood.org)

 

Figure 2 Plum Curculio
Figure 2
. Damage from egg-laying causes fan-shaped scars (New York State Agricultural Experiment Station, Cornell University, Bugwood.org)

Management and other important facts

  • At the time of blooming, monitor for adult plum curculios by shaking a branch and seeing what falls out of the tree onto a paper plate; monitoring is best done in the morning when the temperatures are cool and the insects are inactive.
  • Insecticides containing the active ingredient malathion are effective; malathion is toxic to bees so do not apply until after petal fall; a second application may be made 7-10 days later.
  • Do not apply insecticides containing carbaryl because this may cause fruit abortion if applied within 30 days after bloom.
  • Practice good orchard sanitation by promptly disposing of fallen fruit.

This website was supported by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through grant 14-SCBGP-ND-0038.
Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.

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