Early action by producers called key to controlling invasive weeds

Red bartsia is a tremendous name for a weed.

It’s also a tremendous annoyance for forage producers in Manitoba’s Interlake region.

The invasive species is native to Europe and arrived in Manitoba in the 1950s, likely in a shipment to the Royal Canadian Air Force base at Gimli.

Since that time, red bartsia has invaded pastures and hayland throughout the Interlake and may now be impossible to eradicate.

“With … extensive seed reserves in the soil, and seed viability in the nine-year range, there is no easy, quick fix for this problem,” the Manitoba Weed Supervisors Association (MWSA) said in a statement.

“With new infestations of red bartsia already appearing in other parts of Manitoba, it’s imperative that all areas incorporate careful monitoring and aggressive control measures to prevent further outbreaks.”

As part of Manitoba’s Invasive Species Awareness Week April 21-27, the MWSA reminds landowners to keep an eye out for red bartsia and other weedy pests.

Grant Shewfelt, supervisor in the Argyle-Lorne weed control district of Manitoba, said red bartsia isn’t a problem on cropland because it can be controlled with cultivation and doesn’t compete with annual crops.

However, it is a headache on marginal hayland.

“The problem up there (the Interlake) is mostly on fields that are … low fertility. The guys producing better hay crops … aren’t having a problem with this weed. They’re out-competing it,” Shewfelt said. “It’s quite isolated to the Interlake, but there have been a couple of other incidents in other parts of the province. We believe that’s been caused by someone purchasing a machine that’s infested.”

Red bartsia isn’t well known because it affects forage land, but Manitoba producers find it harder to overlook the invasive weed waterhemp.

Waterhemp, part of the pigweed family, is a major problem for soybean growers throughout the United States Midwest. The weed can quickly develop resistance to herbicides, particularly glyphosate, the main weed control tool for soybean producers.

In 2018, scientists found a waterhemp plant in Missouri with resistance to six different herbicides.

Over the last five years, it moved from the Midwest into North Dakota and jumped across the border into Canada in 2017, where it was found in a soybean crop southeast of Winnipeg.

“Waterhemp is … capable of producing 500,000 seeds per plant that tend to germinate throughout the summer. (And) late flushes can keep coming after the control measure window has closed,” the MWSA said.

Waterhemp was confirmed in a second Manitoba soybean crop and has likely moved into other fields, mostly in the Red River Valley.

Whether the problem is waterhemp or red bartsia or orange hawkweed, a pest now in southeastern Manitoba, Shewfelt wants landowners to take action on invasive species — as soon as possible.

“(A) rapid response if you see something, so it doesn’t become a real economic problem.”

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