A Thorn in our Side: European Buckthorn

Ontario is home to thousands of trees, shrubs and other plants; many of them native species. Sadly, many non-native species have also been introduced, some of which naturalize and others which become problematic. Those problematic plants are considered invasive species and their presence is taken very seriously. They often overtake native species and threaten their very existence. In fact, in London, Ontario, one of those invasive species has become our most common tree—European Buckthorn.

European Buckthorn

Common buckthorn leaves and flowers. Photo: Credit Valley Conservation Area

European or Common Buckthorn was introduced to North America in the 1880s as an ornamental shrub. As its name suggests, it is native to Europe and Asia, but has spread aggressively from Saskatchewan, across Southern Ontario, and east through to Nova Scotia. It is up to everyone to help combat this invasive weed.

How to Identify:

European Buckthorn is a small perennial tree or shrub, growing 2-3 metres tall and has small black berries in the late summer, into fall. The glossy green leaves are some of the first to come out in the spring and the last to drop in the fall. Leaves are opposite, finely toothed and 2.5-6 cm long. Yellowish green flowers appear in May-June and have 4 petals with male and female flowers appearing on separate plants. Bark is grayish brown and older twigs end in sharp thorns. It is tolerant of many soils and habitats, making it a wide-spread danger to all.

European Buckthorn berries

European Buckthorn is highly invasive and creates dense thickets which shade out surrounding native plants. It also hosts oat rust, which is of concern to the agricultural sector, as well as forest management groups. Because of this it is considered a noxious weed under the Ontario Weed Control Act. Add to that the combination of high seed production and great seed viability, and European Buckthorn spells bad news all around. Its rapid spread puts it near the top of the list of invasive species in need of eradication.

Illustration of Common buckthorn by Andrea Kingsley

What to Do:

Any time you come across an invasive species in the wild, the first thing you should do is report a sighting to the Ontario’s Invading Species Awareness Program. There are plenty of strategies to deal with invasive species, depending upon the plant. Always make sure you properly identify the plant in question before handling it and use proper protective gear to ensure your safety.

• PREVENTION is the first step: Learn how to identify European Buckthorn. Avoid using it or other invasive species while gardening. Choose native or non-invasive species from reputable garden centres when planting
• REMOVAL: Manual or mechanical removal of buckthorn involves hand-pulling, mowing, grazing (bring in some goats to help!), cutting or girdling, followed by prescribed burns (always contact your municipality first), and yearly follow-up to remove any new plants (seeds can remain viable in the soil for up to 5 years)
• DISPOSAL: Never discard invasive species in compost piles or in the wild. European Buckthorn can be burned, but safe handling is key to avoid painful wounds from their thorns. Dispose of European Buckthorn in the garbage.

Together we can make a difference. Do you part to prevent and reduce European Buckthorn in Canada.