Russian olive, good tree or invasive weed?
February 28, 2012
Let’s face it: growing trees in harsh Nevada climates, particularly outside of urban cores, can be difficult. It seems as if a tree that can grow without water or attention in northern Nevada would be a blue ribbon winner. But, with Russian olive, that is not the case.
Russian olive is a scrubby, thorny small tree that can grow to 30 feet in height. Its leaves are silvery green, stems reddish and flowers yellow. The flowers are followed by little “olives” loved by birds. These trees are hardy, needing little water, which in an arid environment seems to be a good thing. They gather their own nitrogen in their roots and are able to grow in poor soil. So, what’s the problem?
Russian olives grow freely along streams, rivers and lakes (riparian areas), outcompeting native vegetation and often forming dense thickets. They interfere with natural plant succession and tax water reserves. Although they need little water, they will use more water when it is available, taking it away from more desirable species. In addition, while birds love the olives, numbers of bird species are higher in riparian areas dominated by native vegetation.
As more riparian areas are being taken over by Russian olives, land managers are treating them as invasive weeds. One method of control of larger older trees is called “hack and squirt.” It involves cutting into the cambium layer – the green or white moist tissue under the bark – to create a little cup. A chemical is placed into the cup to kill the tree. Medium-sized trees can be controlled by painting stumps immediately after cutting with the appropriate chemical according to label directions. Smaller plants can be sprayed at the base. Treatments and chemicals used vary with the site, the time of year and the age of the plant.
Land managers, particularly those along rivers and streams, hope people will eliminate their Russian olives to reduce seed sources. This will help reduce the number of plants they have to control. Russian olives can be replaced with their cousin the buffaloberry, a very similar looking native plant that is not invasive.
If you are interested in learning more about weeds, soils, vegetable and fruit growing, turf and plant care, consider becoming a Master Gardener. The next training in Carson City and Douglas County is March 5 through May 1, on Mondays and Tuesdays from 9 a.m. until noon. The fee, which includes a number of books and publications, is $185. Call Wendy Hanson at 775-784-4848 for more information. Or, email firstname.lastname@example.org.
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JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at email@example.com or 887-2252.