Thorny problem: invasive Himalayan blackberry plant found in Yarmouth

Nova Scotia is dealing with a new invasive species that could pose competition for low-lying vegetation and native fruit.

The Nova Scotia Invasive Species Council says the Himalayan blackberry has been discovered in Yarmouth, making it a first for the province.

Despite the name, the thicket-forming shrub doesn't originate in the Himalayan mountains, but the Armenian region.

Kirsten Noel, council supervisor, said the plant was discovered in the past week at a few different sites in Yarmouth, including along the waterfront and the Yarmouth County Rail Trail.

"It's our suspicion that it was intentionally planted in a garden by somebody that probably didn't understand how invasive it was or how aggressive it grows," Noel said.

She said that "aggression" is what sets it apart from native blackberries.

It can grow up to five metres tall and uses canes — long, thin branches — to move. The canes can grow more than 10 metres in length and root wherever they touch the ground, helping them to create new plants.

The berries themselves are a bit larger than those grown on native species, don't have the trademark hairs and are a bit more tart in flavour.

Himalayan blackberry shrubs are also dense and covered in thorns, creating large walls that can block access to waterways and trails.

"They don't grow in harmony with our native species," Noel said. "A lot of the time, invasive species out-compete our native species for important resources like food or nutrients or space. Eventually, it could reduce biodiversity."

Part of the draw of planting the berry is its fruit output, said David Sollows, the chair of the UNESCO Southwest Nova Biosphere Reserve Association. He said that is especially true since the plant will flower and bear fruit continuously until frost sets in.

Sollows said getting control of the plant in the early stages of its spread is crucial.

"Once it gets established in things like fields and areas that are for agriculture, it can create really dense barriers of huge, thorned branches that are pretty much impenetrable," he said.

It's likely some of the plant's spread is due to birds eating the berries and dropping the seeds. Sollows added that the climate and coastal exposure may also be playing a part in how well the plant is doing in Yarmouth.

Though this is the plant's first appearance in Nova Scotia, it's already been seen in other Canadian jurisdictions. British Columbia has long dealt with the plant, which has been found in the Lower Mainland and Vancouver Island.

Noel said the council will likely be able to control the plant's growth since it was detected early. She said the group plans to reach out to other invasive species councils that have dealt with the berries to get a sense of the best plan of action. 

Eventually, a management plan will be developed to outline how the council will deal with the existing plants.

"That could include outreach and education, as well as [manually] cutting the shrubs down, digging them up," Noel said. "It's definitely something that's on our high-priority list now that we know that it's there."

Sollows echoed the sentiment and said education is an important piece in getting the berry plant under control.

"Convincing the public that you really don't want it … can be a challenge," he said. "It's a plant that will eventually start costing municipalities and people in agriculture money to eradicate it."