Preparing for Plum Curculio

These damage sites, seen above, are called oviposition stings.  They are easily identified by their crescent shaped cuts. Unlike codling moth, the larvae of plum curculio rarely cause damage to the fruit. 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.

The question then becomes, 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®) or any pyrethrin  based spray as these are highly toxic to honey bees and other pollinators as well as any beneficial insects. Any other pesticides should be applied in the evening when the honey bees have returned to their hives.

For home growers, an acetamiprid spray such as Ortho® Flower, Fruit & Vegetable Insect Killer Ready-Spray is a deterrent. This product has been discontinued by Ortho, but may still be available in concentrated or Ready To Use (RTU) form on eBay or elsewhere online.

If no blooms are present on any trees, then a pyrethrin based spray may be used as a deterrent, even though there may be no fruit set. Picking up and disposing of any fallen fruit will reduce problems with plum curculio, other insects, and many plant diseases. For conventional growers, Avaunt or Assail are two choices you might use, based on your codling moth protocol and your apple maggot protocol.

A relatively new option for backyard growers is Bonide Fruit Tree and Plant Guard.  This is a multi-purpose fruit spray that is a complete concentrate that contains insecticide, fungicide, miticide, aphicide, and scalicide. Designed specifically to protect home orchards from the ravages of listed insects and diseases. The active ingredients are Lambda-cyhalothrin: 0.5%, Pyraclostrobin: 3.06%, and Boscalid: 5.622%.  Lambda‐cyhalothrin is a synthetic pyrethroid insecticide that is similar to naturally occurring pyrethrin insecticide compounds found in chrysanthemum flowers.   It also contains the same fungicide ingredients that are in Pristine, a fungicide used by commercial growers.  It should only be used after petal fall and sprayed in the evening after bees and other pollinators have retired for the day.   When using a multi-purpose fruit spray, no other insecticides need be used, but other fungicides can be rotated with the MPFS. 

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 at 7 to 10 day intervals or after any rain. And, as always, follow all label directions on any spray product. 

For a complete Fact Sheet on Plum Curculio, consult the Cornell University   Plum Curculio Fact Sheet  for an in depth look at this pest

This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author assumes no liability resulting from the use of these recommendations.