Deb Babcock: Special alert on cherry trees |

Deb Babcock: Special alert on cherry trees

Deb Babcock

Editor’s note: This story has been updated to include Western Tree Management in the list of tree sprayers.

Late in summer 2010, just as local home gardeners were bringing in cherry harvests, we discovered a problem with some cherry produce in Routt County. In certain areas, ripe cherries were found to be infested with white, maggot-like larvae from the western cherry fruit fly. This has been particularly noticeable in cherries from home gardens in Old Town Steamboat Springs but could spread to a wider area. Once a cherry has been infected, the fruit is no good.

We want to get a jump on this destructive pest early in the hope of saving some cherry produce this season. The Colorado State University Routt County Extension and its Master Gardeners will be hosting a free workshop about the cherry fruit fly at 5:30 p.m. Tuesday at the Steamboat Springs Community Center.

The western cherry fruit fly was first found in cherries in the western part of Colorado in the late 1990s and now has found its way to Routt County, probably on trees brought in to meet demand for this popular plant. This pest attacks only cherries and is a problem with all varieties. It will not harm the tree, just the produce.

The western cherry fruit fly produces one generation of offspring per year. The pest spends winter in the soil as a pupa and comes out as an adult fly during a two month period in spring when temperatures warm up. The fruit fly lays its eggs (50 to 200 per fly) in the cherry fruit, with one egg per cherry, when temperatures reach 75 to 85 degrees. The eggs hatch within a week, and the larvae spends the next two weeks inside the fruit, ruining it, before burrowing out and falling to the ground to push itself into the soil to spend winter as a pupa.

Smaller than a housefly, the western cherry fruit fly has a black body with thin white stripes across its stomach. Once it reaches adult stage, it can be identified by a pattern of distinctive black markings on its wings.

Recommended Stories For You

Home gardeners are asked to hang yellow sticky traps from tree branches in early spring when cherries are green. Check it daily until you spot the first fruit fly, and then begin a spray program within a week. We hope to have a supply of these strips available at the Tuesday workshop.

There are four primary controls recommended for eliminating this pest. Spinosad is the least toxic to mammals, will last about a week and should be repeatedly sprayed until a week before harvest. It can be found under the Fertilome and Natural Guard labels.

Carbaryl products such as Sevin also are effective but can cause spider mite problems if used repeatedly. Therefore, you should alternate this product with other ones.

There are several products containing malathion that can be used to control cherry fruit flies, but they have just a two- to three-day residual value so that needs to be applied often.

And two pyrethroid insecticides called permethrin and esfenvalerate can be used for cherry fly control. These insecticides give a week or more of residual value.

Keep in mind that with any of these controls, as your cherries grow larger, the fruit will outgrow the insecticide. As a result, you need to stay on top of spraying as the fruit expands in size. If your cherry trees are quite large, you might need to contract with a professional.

If you have any questions about your cherry trees, contact the Extension Office or come to our workshop Tuesday.

Deb Babcock is a Master Gardener through the Colorado State University Routt County Extension. None of the products or professionals mentioned in this article are endorsed by the Master Gardener program but are provided for informational purposes. Call 970-879-0825 with questions.

Local tree sprayers

■ Catamount Spraying Co., 970-471-6240

■ Doran Agri Services, 970-870-0994

■ Hedges Spraying, 970-583-7468

■ Higo Weed Busters, 970-723-4588

■ Northwest Weed Management,


■ Sol Solutions, 970-871-1338

■ Stinton Enterprises, 970-819-6416

■ THC Enterprises, 970-627-3359

■ Western Tree Management, 970-870-7987

■ Wilderness Weeds, 970-216-6151

Go back to article