Russian olive tree, an invasive species in America, how to control it

Russian olive tree branch with flowers that will turn into fruits to spread and invade more territory

The Russian Olive tree, as opposed to the native American silverberry, is considered a highly invasive species in some parts of the United States and Canada.

The latin name of this tree is Elaeagnus angustifolia and although it looks very similar to the common olive tree,  they belong to different plant families. Getting rid of Russian olive is very labor-intensive but quite straightforward.

Russian olive tree, a short story

This short tree is actually native to central Asia and Eastern Europe. Reports of its use date back to ancient Persia and India, since edible Russian olive fruits were harvested for oil.

This hardy and vigorous plant spread to many parts of Europe, and until today, Russian olive is used there as an ornamental and useful shrub.

The many qualities of Russian olive set the stage for its introduction in North America: a fast-growing, resilient plant was needed to stave off erosion. In the early XXth century (1900s), horticulture stores imported Russian olive and sold it to their customers. It helped mark property edges, stabilize river banks, provide melliferous flowers for bees and serve as wind-resistant ornamental hedges.

Russian olive then started spreading and overcrowding native vegetation. The very reasons for which it was imported led to an imbalance in local vegetation. Upcoming generations are now learning to control Russian olive, truly a force unleashed by their forefathers.

Russian olive is highly resilient

Russian olive is hardy down to -40°F (-40°C)! It also survives periods of drought and warm to hot temperatures too. It is an extremely vigorous tree that doesn’t have any natural competitors.

To sum it up, Russian olive:

  • is very resistant to the cold,
  • withstands hot temperatures,
  • survives droughts and dry spells,
  • grows back vigorously when cut down,
  • fends off deer and grazing animals with thorns and spikes.

Additionally, Russian olive berries are prized by many bird species who eat them throughout the winter. Birds then expel the seeds near and far, and these germinate early and grow fast. One single fruit-bearing shrub can thus spread over vast distances.

  • Russian olive spreads quickly because animals disseminate it in their droppings.

How does Russian olive impact the local environment?

Russian olive tree growing dense and opaqueLocal fauna and flora are affected by Russian olive as it spreads. This fast-growing plant crowds vegetation out and native plants have trouble germinating, growing, and spreading their own seeds.

Whenever a particularly severe frost spell or dry spell kills native plants off, this hardy and drought-resistant plant bounces back much faster.

Also, Russian olive tends to alter nitrogen reserves in the soil, fixating it in the roots and wood. This reduces the amounts of nutrients available for other plants who often can’t compete with the newcomer.

Russian olive has been shown to outgrow and crowd out native willows, black cottonwood, poplar, elm, and even other invasive species such as saltcedar (also called tamarisk) and more.

In most cases, Russian olive grows dense and lush and keeps other seeds from germinating under it. Since the canopy of native species are more sparse and let the sunlight through, the following cycle develops:

  • Russian olive seeds brought by animals sprout.
  • They germinate in part shade provided by native species.
  • Russian olive grows and creates an impenetrable underbrush under the native canopy.
  • Native seeds don’t have enough light, water and nutrients to sprout and grow.
  • As older, taller native trees die off, Russian olive takes up the space.

Native trees are only left with perilous and unstable places to germinate like riverbanks and temporary islands within the riverflow.

Within a couple decades, the flora of an entire area can be replaced.

Controlling Russian olive, raising awareness

Urging locals to take action against Russian olive

What makes dealing with this plant quite difficult is that it’s also very appealing: the fruits are useful and the fragrance is nice, so it’s difficult to raise awareness about the invasiveness of Russian olive.

Moreover, getting rid of Russian olive is a bane because of its thorns and the vigorous growing back. Even persons who understand the issue don’t easily engage into the work-intensive labor required.

But it actually isn’t so difficult to reduce Russian olive infestations once your mind is set to it.

Local regulations written to control Russian olive

In both the United States and Canada, local governments where the plant has become invasive have added Russian olive to their noxious weed list. The local Department of Agriculture can inform you on whether your area is subject to restrictions on growing Russian olive.

Possible restrictions can be that:

  • it is illegal to plant, grow or cultivate Russian olive,
  • sale of Russian olive not allowed,
  • transplanting Russian olive is not permitted,
  • commerce or sharing of Russian olive seeds is disallowed,
  • cutting down or removing of existing specimens is mandatory.

Usually, local ordinances and governments can support taking action through:

  • Russian olive weed-control programs,
  • propagation maps and zone reports,
  • dedicated forest management teams and task forces,
  • stipends or grants to refund expenses for removing Russian olive,
  • hotlines or complaint lines to report places where Russian Olive grows.

How to stop invasive Russian olive

As said earlier, it’s very labor-intensive to wipe out Russian olive trees over a wide area. However, it is possible, and the recommended method to kill Russian olive without endangering native plants is the cut stump method.

  • Wear protective clothing against thorns.
  • Cut the Russian olive at the stump as low as you can.
  • Apply a natural herbicide directly on the stump along the outer growth rings.

Remember that if you don’t apply the herbicide, the Russian olive will grow back even more vigorous than before. High-strength vinegar will do the trick.

A few tips on how to make weeding out Russian olive easy:

  • Use a chainsaw or even heavy forest machinery to speed the cutting up, if you’ve got a large surface to cover.
  • Work as a team, with one person cutting and the other spraying the natural herbicide on the cut stump.
  • Check that you also get rid of smaller trees and saplings.
  • Spray only the outermost growth rings to save on herbicide, since the center won’t sprout anyways. Focus on the live circle just near the bark.
  • Seedlings under a year old can be pulled out manually with the root.
  • Spray more vinegar on the stump every fortnight for two months.
  • Check in subsequent years for new growth.

Other weed removal solutions are ineffective against Russian olive, so don’t try to ignite fires, spray herbicide on vast areas, or simply cutting without using herbicide.

Smart tip about cutting Russian olive down

Since Russian olive also propagates through layering, don’t keep cut branches laying around in moist, fertile soil: some might sprout again. Gather them up and dispose of them diligently.

Invasive Russian olive on social media

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Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Yellow-flowered Russian olive (also on social media) by Lazare Gagnidze under © CC BY-SA 4.0
Prolific Russian Olive tree by Famartin under © CC BY-SA 4.0