Ask SAM: Russian olives fall out of favor

This column is provided by Larimer County Extension's Small Acreage Management (SAM) Program to assist rural residents.

Dear SAM,

I have several Russian olive trees on my property. A friend told me that not only are these trees no longer sold in Colorado, but they are now considered a weed. Do I have to remove the trees?

Adam

Dear Adam,

Your friend is correct. The Russian olive, once recommended for windbreaks, erosion control, wildlife and landscaping, can no longer be sold in Colorado. In fact, the Russian olive is listed as a noxious weed by the state.

In Larimer County, landowners are not required to remove Russian olive trees. Eliminating trees and preventing their spread is encouraged, however.

Russian olive trees, which are not true olives, are recognizable by the silvery-green tint of their leaves. The trees reach a maximum height of about 30 feet. Thorns grow from their branches, and the tree produces a silver or reddish fruit the size of a large olive. Several bird species feed on the fruit and spread the tree's seeds.

The Russian olive fell out of favor when it became invasive, especially in riparian areas. Much like tamarisk, Russian olive displaces native vegetation and impacts wildlife habitat. While some birds eat the tree's fruit, significantly more bird species are found in stands of native cottonwoods and willows.

In dry upland areas, away from drainages, the Russian olive is less aggressive. Removal of trees is encouraged on upland sites, but the concern is not as great. If the trees are providing shelter from the wind, you might consider planting a second windbreak. Remove the Russian olives when the new planting grows tall enough to provide the desired shelter.

When you cut a tree down, new shoots often grow out of the stump. To prevent this, treat the cut stump with an approved herbicide. Several products with triclopyr, imazapyr or glyphosate as an active ingredient are effective. The treatment should be applied immediately after felling the tree. Read and follow directions on the product label.

Foliar herbicide applications can also be effective for Russian olive control, but are usually used only on small trees or shrubby stands.

Wood from the Russian olive is useful as firewood.

Unfortunately, there are no known biological controls for Russian olive in Colorado.

Contact the Larimer County Extension Office at 498-6000 or Larimer County Weed District at 498-5768 for more information on Russian olive management.

The Colorado State Forest Service has information on planting windbreaks. Now is the time to order seedlings for spring planting.

SAM

Have a question about rural living? Write to Ask SAM, Larimer County Cooperative Extension, P.O. Box 543, Fort Collins, CO 80522.