• Hydrilla – priority class 1
• Eurasian Water Milfoil – priority class 3
• Curly Leaf Pondweed – priority class 4
• Flowering Rush – priority class 4
• Purple Loosestife – priority class 4
• Saltcedar – priority class 4
• Yellowflag Iris – priority class 4

For more information about the priority classes  for FWP’s  Aquatic Nuisance Species visit their website.

I. Introduction: History/Identification/Threat for Russian Olive

A. Russian Olive History: Russian olive (Elaeagnus angustifolia L.) is a member of the Oleaster family. Russian olive originated on the European Continent and ranged from southern Europe to western and central Asia (Little 1961). Russian olive was introduced to the United States in the early 1900’s. Tolerant to diverse site conditions, Russian olive has been planted as an ornamental (Little 1961), and used extensively in shelterbelts in the drier regions of the Great Plains and Rocky Mountains (Read 1958). In Montana, east of the Continental Divide, Russian olive trees have been used in shelterbelts, windbreaks, wildlife habitat, ornamentals and for wildlife habitat. Plants that have naturalized thrive along riparian corridors, irrigation delivery systems, pastures, saline affected areas and some wetland sites.

B. Russian Olive Identification: Russian olive is a large, thorny, perennial deciduous shrub or small tree (up to 40 feet). The leaves are alternate and simple, elliptical to lanceolate in shape, 1 to 3 inches long and ½-inch in width, scaly on the top and silvery and scaly on the bottom, dull green to gray in color. Stems may be thorny. The bark appears smooth and reddish brown to gray in younger trees and becomes unevenly rigid, wrinkled and graying in color as it matures. The fruit is berry-like, approximately ½-inch in length, dry, mealy, sweet, and edible.

C. Russian Olive Threat: Russian olive infestations threaten native plant communities in riparian areas and grasslands, as well as irrigated pastures and hay land. Russian olives have been identified along all of the watersheds in eastern Montana. Along riverine areas native cottonwood and willow species are being replaced by Russian olive through competition and succession. Russian olive grows relatively quickly and develops a dense canopy; preventing shade-intolerant native vegetation from establishing. Katz and Shafroth (2003) report that Russian olive constitutes a new functional guild; it can establish beneath the canopy of native riparian trees and can form self-replacing stands. In addition, there are selective pressures from mammals. Lesica and Miles (1999) observed that beavers select cottonwood and willow over Russian olive to forage on; providing Russian olive plants an additional competitive edge over native woody riparian vegetation.

Download the complete technical note MT-30 and attachment.

Saltcedar is native to Eurasia but was introduced to North American in the early 1800’s as an ornamental and also for erosion control.  It was quick to escape cultivation and has since been spreading rapidly.  This attractive shrub has characteristics similar to an evergreen but looses its leaves in the colder months and is therefore considered deciduous.  Saltcedars readily establish along waterways, streams, canals, banks, drainage areas, and anywhere that the soils are exposed to an extended period of moisture.

Saltcedar has become well established throughout the southwestern United States and Mexico.  There are also extensive infestations in many of the northern states and small but well-established stands in Oregon, Idaho, Montana, Wyoming, South Dakota, and North Dakota.  In most western Montana counties, these shrubs are found as ornamental in landscaped yards.

Concerns

This long-lived shrub (50-100 years) can spread by both vegetative re-growth and seeds.  Each flowering shrub produces around 600,000 seeds.  Not only are they long lived and have great reproductive capabilities, but they also grow extremely rapidly.  Most of these shrubs can flower the same year they germinate.  They exclude native vegetation by exuding salts above and below ground.  This creates a saline crust, which inhibits other plants from growing in close proximity.  The other main concern with Saltcedar is its consumption of large quantities of water.  One shrub can consume up to 250 gallons of water in 1 day.  This can result in lowering the ground water and drying up springs and marshes, which in turn lessens the amount of water available in riparian areas.  Saltcedar’s dense roots also slow down river flow, which increases deposition of sediments along the river bank.  This widens the riparian zones causing a severe reduction in streamflow or rechanneling, which creates more habitat for Saltcedar to colonize.

Identification

This shrub can reach heights of up to 25 feet and has dense branches that often make it many feet wide.  The narrow leaves of a Saltcedar resemble those of a juniper but they fall off in the colder months unlike junipers.  This shrub is also known as a smoke tree because of it beautiful plumes of deep pink to white flowers that crowd the tips of the branches.  The bark of a Saltcedar is reddish-brown, while the wood is soft and white.  The smooth bark becomes furrowed with age.

What can you do?

Saltcedar is very difficult to control.  A combination of methods is the most effective means of control.  Cutting the stump and immediately applying herbicide has proved to be successful.  The herbicide has to be applied within 1 minute of cutting the shrub or it will not penetrate into the stump.  If you have a Saltcedar or you know where one is please contact your local weed district.  We will be happy to help in the proper control of these highly invasive shrubs.

Visit the MWCA Weed ID pages for additional information and pictures of saltcedar.

This series of articles was developed by Ravalli County.  If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.