Invasive weed causes alarm in Alberta

Phragmites australis chokes out other plants, destroys wetland ecosystems and can pose a fire hazard when it dies

It’s tall. It’s nasty. It’s invasive.

“It scares the crap out of us,” said Todd Green, director of agricultural services for the County of Newell.

Green was speaking about Phragmites australis, a member of the reed family that was found in the county last year and has since been found in 13 other Alberta locations.

Phragmites has spread widely in Ontario and parts of the United States but is assumed to be a relative newcomer to Alberta, although Green said there’s no way of telling how long the pest had been growing in the province before it was identified.

Alberta has native varieties of Phragmites, but australis is an introduced species that can choke out other plants and destroy wetland ecosystems. It reduces habitat for fish and wildlife, and its dead stalks can be a fire hazard.

It is tall, with feathery seed heads, and it favours standing water or generally moist conditions.

Green sounded a warning about the invasive plant at the Alberta Irrigation Projects Association conference in Lethbridge Nov. 22.

He thinks eradication is achievable in the province, but it will require close monitoring.

“My understanding from the province is that all the sites are containable,” he said in a later interview. “They’re not really large, widespread patches so we are still, we believe, in the eradication stage.”

The species is not listed under the Weed Control Act, which is a complicating factor that limits proscribed action against the weed.

However, it is listed as a threat in the fisheries act, which provides for Alberta Environment involvement in control and eradication efforts.

Green speculated that Phragmites australis arrived in the County of Newell, which is the region around Brooks, Alta., aboard a train because the first patch was found along the Canadian Pacific Railway right of way.

“We assume that’s how it came in was from a CPR train that dropped off either a seed or a part of a plant,” he said.

“It is very close to an EID (Eastern Irrigation District) canal, kind of a slow drain into a wetland, and there’s a major canal just to the south, so not good news for us.”

In 2016, county personnel cut down and removed a large patch of the reed within the EID using garden shears and tree trimmers. Four truckloads of the plant were buried in a landfill.

In 2017, special permits were obtained to spray, a tricky proposition when dealing with plants in water bodies. Only two products are registered for control, imazapyr and glyphosate, but only the imazapyr product was used, Green said.

Sites were sprayed in Newell and within the city of Medicine Hat, where another patch was found along the CP line near Ross Creek.

As of now, the pest has been found as far away as Grande Prairie, mostly at sites associated with railways and roads. Green said it may be spreading in shipments of grain, hay or straw.

Among its pesky properties is the reed’s ability to spread by seed but also by rhizomes and sprouting from nodes along its stalks.

Green said it is taller than native varieties. Plants up to 13 feet high were found in Newell in 2017, even though it was a very dry year.

It can also be distinguished from native varieties because it has a tan or brown colour on the stalk below the leaf sheath. Native varieties are red in that area.

As well, the seed head is larger on the invasive type.

Green said anyone who thinks they’ve seen a stand of Phragmites australis should contact the agriculture services board in the region so quick action can be taken.

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