Jun 14, 2021

First adult Western cherry fruit fly expected to begin emergence in Oregon

All cherry trees owners should be aware the emergence of the first adult western cherry fruit flies is expected to begin on June 14 in the La Grande, Oregon, area. 50% adult fly emergence expected June 27. Peak egg laying will occur July 1. Please note that eggs laid by the earliest emerging adults will hatch a few days before 50% of the adults emerge from the ground!

Initial spray applications should be made within the first week after emergence and then follow-up spray applications should be scheduled to control CFF until harvest. The insecticide product label will provide recommendations for spray application frequency and pre-harvest interval requirements. Reminder…….one spray application does not provide season-long CFF control! Adult CFF continue to emerge from the ground through the late June and lay eggs into July.

Management options for the Western Cherry Fruit Fly (CFF) include:

• Spray your own tree(s) with registered insecticide products. See “A Few Pointers for Spraying Backyard Trees” section towards the end of this letter.
• Hire a licensed commercial pest control company to spray your tree(s). It is best to hire the company in early to mid-May so they can prepare in advance of CFF emergence. To locate potential service providers, check the yellow pages for commercial pest control companies (CPCC). At this time, Ridley Pest Control is offering local sweet cherry tree spraying services
• Remove all blossoms or fruit from your tree(s) prior to CFF emergence.
• Voluntarily remove any tree(s) if you never pick the fruit nor manage pests in the trees.
  • Fruit trees not used for fruit production should be replaced with a true shade tree species. Fruit trees can harbor a variety of insect and disease pests that can/will impact neighboring trees so pest management is critical! The Union Co. Cherry Fruit Fly Inspector does offer a free service to cut down any cherry tree(s) the owner no longer wants. However, the wood will be left on site.

– Darrin L. Walenta, Oregon State University