TO: Union County News Media, Commercial Cherry Orchard Managers, & Home Gardeners/Orchardists
FROM: Darrin L. Walenta, OSU Extension Agent Union Co.
RE: 2017 – First Adult Western Cherry Fruit Fly Expected to Begin Emergence on June 6!

All cherry trees owners should be aware that the emergence of the first adult western cherry fruit flies is expected to begin on June 6 in the La Grande area. 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. Reminder…….one spray application does not provide season-long CFF control! Adult CFF will 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:

  1. Spray your own tree(s) with registered insecticide products. See “A Few Pointers for Spraying Backyard Trees” section towards the end of this letter.
  2. 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 (910-7378) is the only local CPCC known to offer fruit tree spraying in 2017. Any CPCC licensed by OR Dept. of Ag to offer fruit tree spraying services is encouraged to contact OSU Extension.
  3. Remove all blossoms or fruit from your tree(s) prior to CFF emergence.
  4. Voluntarily remove any tree(s) if you never pick the fruit nor manage pests in the trees.
    • Fruit trees not used for fruit production (e.g. “shade” only) 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.

Tree height and canopy influence effectiveness of sprays. Shorter trees pruned to open up the canopy allows for more effective spray coverage. For further information on the cherry fruit fly management and products for CFF control, please contact the Union County Extension Office (963-1010) or refer to the following references which are available at your local Extension Office or or the OSU website.

EC 631 Managing Diseases and Insects in Home Orchards

Be sure the insecticide you choose is labeled for use on fruit/cherry trees! Always read and follow label directions for safe pesticide use, frequency of application and pre-harvest intervals!
CFF Biology Notes: Cherry fruit flies spend about 10 months out of the year as pupae in the soil. For the first week after emergence, adults feed on any available sweet substances & moisture. Adults begin laying eggs in fruit 7 days after emergence. Adult emergence continues for up to 2 months. Eggs hatch within 7 – 10 days then larvae feed in the fruit for 2 – 3 weeks. Larvae then emerge from the fruit, drop to the ground and pupate in the soil over-winter until this time next year. Visit the OSU Integrated Plant Protection Center to use the on-line WCFF phenology model (Ali Niazee 1979).
A Few Pointers for Spraying Backyard Fruit Trees
Many homeowners this year may consider spraying their own fruit trees due to limited availability of licensed pest control companies. The window of opportunity for managing many fruit tree diseases has passed but insect pest management needs are ramping up. Here are a few pointers to consider before attempting a spray application to fruit trees:

  • Thoroughly cover the entire canopy and tops/bottoms of leaves. You will need a sprayer powerful enough to reach to the top of the tree canopy. It is not a safe practice to stand on a ladder to make any application and not something I recommend!
  • Choose the right sprayer with the right spray volume capacity for the job.
      • Trombone or slide-type sprayers; small powered sprayers with appropriate spray gun/wand; and a few specialized hose-end sprayers are designed to deliver diluted spray to the tops of mature, standard-sized fruit trees. Always use an anti-backflow device with hose-end sprayers to prevent back-siphoning of pesticides into your home water system.
      • Small hand-held pump sprayers and backpack sprayers do not have the power nor volume capacity to spray mature trees but would work for young fruit trees, vines, bushes and low-growing plants

    (e.g. strawberry).

  • Determine spray volume needed for a tree by applying clean water to the tree with the selected sprayer. Some large trees may require up to 10 gallons of spray solution, whereas, small trees may need only 0.5 to 1.0 gallon of spray solution.
  • Correctly identify the target pest then apply the proper dosage of the correct pesticide at the correct timing for the target pest.
  • Do not apply herbicides with the same sprayer used for fungicide/insecticide applications to fruit trees.
  • Choose a pesticide registered for use on fruit trees (see label) then follow all safety precautions on the label to ensure safe pesticide use, frequency of application and pre-harvest intervals!

Darrin L. Walenta
Extension Agronomist
OSU Extension – Union, Baker, Wallowa Co.
10507 North McAlister Road
La Grande, OR 97850
Phone: 541-963-1010
Fax: 541-963-1036