Kamloops, B.C., working to remove invasive Russian olive trees — but it could take decades

Russian olive trees — sometimes known as silver berry or oleaster —  are small, ornamental plants with silvery leaves and black bark, and small yellow flowers and silver fruit that look like miniature olives. They’re pretty, but they’re a problem. 

The species is invasive in B.C., having been brought to the province from its native range in Russia and other parts of Asia, according to the Invasive Species Council of B.C. And that’s why some communities, like Kamloops, are looking to get rid of them. 

Russian olive is a hardy plant that can survive in dry conditions and cold temperatures, making it perfect for a climate like that of Kamloops, a semi-arid, desert-like city in B.C.’s Interior. 

They take in more water than most plants in areas where the soil is dry, which means they can outgrow native plants, the invasive species council says. 

“Whenever you have a non-native species, there's some that are fairly assertive, aggressive and those are the ones that we are concerned about,” council executive director Gail Wallin said. 

She said Russian olive are “huge competitors” for water. 

“In a time when we're really concerned about water and water availability for our native species and for habitats, that's a real concern.”

But getting rid of them isn’t so easy. Because they have a strong root system and will grow back if every bit of plant isn’t removed, extra care has to be taken, according to Wallin. 

In Kamloops, the city is taking a different approach. 

Instead of pulling up trees and risking not getting the roots, or spraying them with pesticides that could be harmful to the ecosystem, the city is using biological controls — bugs. 

Aceria angustifoliae are small mites found in Europe and Asia, according to Kirsten Wourms, the crew leader of natural resources for the City of Kamloops.

She said the mites affect the flowers, the fruits and new young shoots of the trees so that they cannot reproduce.

“Over time, we're actually looking at the Russian olive population decreasing,” Wourms said.