With the blooms off the apple trees now, and the temperatures predicted to be in the 80's this week, it is prime time for our ugly little friend, PC! Adult plum curculio beetles, pictured to the left, emerge in the spring, around petal fall, to feed on apple buds, flowers, leaves and young fruit. Female beetles cut holes in the young fruit and deposit one egg in each cavity. These sites are easily identified by their crescent shaped cuts. Unlike codling moth, the larvae of plum curculio rarely cause damage to the fruit.
Damage
The fruit is primarily damaged superficially by the egg-laying and feeding by the adults. These "stings" will cork over and cause an indentation in the fruit as it matures making it look deformed and unsightly.
Control
The question is, how do we control them?? Pesticide application at this time is very important for plum curculio control. To prevent fruit drop, and due to toxicity to bees if there are still blooms on the trees, do not use carbaryl (Sevin®). For home growers, an acetamiprid spray such as Ortho® Flower, Fruit & Vegetable Insect Killer Ready-Spray and picking up and disposing of fallen fruit will reduce problems with plum curculio, other insects, and many plant diseases. For conventional growers, Calypso or Assail are two choices you might use, based on your codling moth protocol and your apple maggot protocol. For a pure organic spray, the two most frequently used insecticides are Surround® and Pyganic®, both certified organic. The organic products may need to be sprayed multiple times for complete control. As always follow all label directions on any spray product.
