'A bad year for purple loosestrife': How the invasive plant species is being fought in Manitoba.

Ross says purple loosestrife is a tall plant - up to 2 metres - with a beautiful pinkish-purple flower at the top. (Source: CTV News Winnipeg)

A perennial pest of a plant is once again popping up in ditches and wetlands across Manitoba.

"It's that time of year. People see purple," said Lisette Ross.

The Head of Wetland Services and Native Plant Solutions with Ducks Unlimited Canada says they do start to get more calls this time of year about purple loosestrife, an invasive species with the potential to devastate wetlands across the country.

It's a tall plant - up to 2 metres - with a beautiful pinkish-purple flower at the top.

"Usually in August, we start to see a lot of pink," said Ross. "So the plants are there and they're flowering, and, of course, the warning flags go up."

Warning because the species is both invasive and noxious, according to Ross.

"It starts to displace healthy vegetation in those wetter habitats that it takes over, whether that’s a ditch or a wetland habitat, or along the lakeside, or along a stormwater pond like we see in Winnipeg or Brandon, she said. "As it displaces these healthier plants, it also takes away some of the benefits. So purple loosestrife doesn’t really have any ecological benefit to it."

The plant first arrived in Canada in the late 1800s, as seeds carried over from Europe in the ballast water of ships. Ross says the species has slowly spread into the prairies from the east, and at one point in the 1990s was cultivated and sold in stores.

Ross says this year has been a bad one for purple loosestrife, with many plants being reported around the province. Weather plays a big role in this.

"This year, unfortunately, we've had very good wet conditions all through the spring and into the summer," she said, "and that produced really good conditions for the growth of purple loosestrife."

The City of Winnipeg told CTV News Winnipeg in an email that "residents can remove purple loosestrife plants from their property simply by pulling out the plant with the roots, and then closing it in a plastic bag and disposing of it along with their regular household garbage."

But Ross says you have to be careful when pulling out the plants, as that may just spread the seeds further.

"Cutting off the seed heads is a really good approach," she said. "The plant is still there, but at least you're not adding more seed to the seed bank."

Ducks Unlimited Canada, the city and the province are all partners in the Manitoba Purple Loosestrife Project (MPLP), which uses a specific species of beetle as bio-control to fight the invasive plant.

"We knew in Europe that it had some natural beetle predators that would keep it in check," said Ross. "The question was, could we bring those to Canada, and would they impact any other species here?”

Ross says the MPLP has been running since the early 1990s. She says it has been working because the beetle's life cycle is so short, going from larvae to adults in just a month.

"(They're) continuing to feed on the leaves and stems of purple loosestrife, thereby causing what we hope is good devastation," said Ross.

The fight against purple loosestrife is ongoing, according to Ross.

The Manitoba Purple Loosestrife Project uses a specific species of beetle as bio-control to fight the invasive plant. (Source: Lisette Ross)

"We inspect a number of different sites, we go back to the same sites year after year to see how the populations are doing, to see if the beetles are migrating to a new location."

However, she says the wet weather is also hindering their efforts here, as high river levels this year have been washing the beetles away.

Regardless, she is grateful for all the tips she gets from Manitobans.

"So many people are noticing it, they're reaching out to say 'hey we've got it in our back yards,' and we just appreciate that.

"People are recognizing it as a plant that really can cause problems, and they're stepping up to help out."

A spokesperson for the province said purple loosestrife is considered an aquatic invasive species under the Water Protection Act.

"There is no obligation for anyone necessarily to control the plant, however, purple loosestrife is listed as (a) prohibited species, so it cannot be possessed, transported or released in Manitoba," the spokesperson said.

They noted property owners should pull the plant out by hand and put in directly into the household trash bin, ensuring that it is disposed of in a way that it isn't able to spread.

The spokesperson added there is currently no funding from the province to help control the weed, even though there had been "sporadic support" over recent years.

"Funding requests are regularly reviewed and if there is the ability to offer support in the future it may be provided again. However, there is no funding commitment at this time."