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. Though 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.

Controlling Russian olive, raising awareness

Urging locals to take action against Russian olive

Russian olive tree growing dense and opaqueWhat makes dealing with this plant quite difficult is that it’s also very appealing. 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.

Biological control against Russian olive

There is, as of now, no perfect solution to control Russian olive through its predators or parasites.

When a particular area has been cleared, it’s important to plant native plants in place of the invasive shrub: the competition will slow regrowth.

Predators of russian olive

Recently, certain insects and mites are under investigation to understand whether it’s a good idea to import them into russian olive-infested areas or not.

Bringing in a natural predator without investing its impact first might backfire: it might attack local plants instead!

A promising candidate is a type of gall-forming mite called Aceria angustifoliae. The name of this mite shows one of its advantages: it seems to only infect Russian olive!

  • This mite reduces the fertility of a Russian olive shrub or tree by at least one-third. The spread is thus slowed by as much, too.
  • The mite doesn’t seem to infect other plants at all.
  • However, it’s never fatal to the tree, so it can’t be used to eradicate russian olive from a given area.

Some animals such as deer and such occasionally nibble on the plant. However, the shrub’s thorns quickly sends them off to browse on other plants.

Diseases to use against Elaeagnus angustifolia

Xylella fastidiosa is a North-American bacteria currently wrecking havoc in olive orchards across Europe.

  • Russian olive is one of this bacteria’s host plants.
  • However, it’s an asymptomatic host: it won’t develop symptoms of being infected, and it certainly won’t die from it.

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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Picture related to Invasive Russian olive overlaid with the Facebook logo.

Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Yellow-flowered Russian olive (also on social media) (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