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Invasive perennial grass threatens irrigation systems

03/26/2018

Officials aren’t sure how Phragmites arrived in the province but are urgently trying to eradicate it

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Phragmites is an invasive perennial grass that can reach heights up to four metres tall and likes to grow in low lying areas with water. When invasive Phragmites is introduced to natural areas, it spreads rapidly, via rhizomes, and can be difficult to control once established.

“It has harmful effects on native species and aquatic ecosystems,” said provincial weed specialist Nicole Kimmel. “Phragmites can drastically alter water movement and can be particularly threatening to Alberta’s irrigation infrastructure.”

While the presence of Phragmites is abundant in North America, Alberta had remained untouched until the first report of invasive Phragmites, near Brooks in the spring of 2016.

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“Since then with awareness and diagnostic support, Albertans have found about a dozen more locations,” said Kimmel. “Identification has been complicated by a similar looking native type of Phragmites.”

In 2016, staff from the County of Newell, the Eastern Irrigation District, and Alberta Agriculture manually removed seed heads and stalks following initial reports of the invasive plants near Brooks and Medicine Hat.

“Physical removal is not a successful stand-alone method but is recommended in conjunction with a herbicide application,” said Kimmel.

Two herbicide active ingredients — glyphosate and imazapyr — have shown to effectively control Phragmites in North America, but neither is currently registered under label for water use in Canada. However, last year, Alberta Agriculture applied for and received emergency use registration for aquatic imazapyr application. During the summer, staff from the County of Newell, Medicine Hat, and the province cut down the plants and applied the herbicide.

“Full success of control treatments will not be fully realized until 2018,” said Kimmel. “As an added security measure, a repeat emergency use will be applied for in 2018 for aquatic locations, in the event any plants were missed.”

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Other locations identified in the province are undergoing land-based herbicide applications. Alberta Transportation is working with local rural municipalities to uproot this invasive weed.

Only invasive Phragmites is a prohibited species and while not currently regulated, it is being reviewed for possible inclusion in the Weed Control Act. The plant was first reported close to the Eastern Irrigation District canals and provincial officials are particularly interested in how it arrived in the province.

“A potential pathway of introduction could be ornamental garden plants which are very harmful if introduced into the wild,” said Kimmel. “We ask everyone to double check before planting any plants to ensure they are not a prohibited species in our province.”

Albertans are encouraged to report any suspected Aquatic Invasive Species to 1-855-336-BOAT(2628).


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