Waterhemp’s noxious weed tier downgraded in some areas of Manitoba

CTV’s Harrison Shin has details on why waterhemp, a noxious weed, is being downgraded in some parts of Manitoba.

In a calm, breezy field filled with crops – an unwelcome imposter might be hiding.

Waterhemp, a fast-spreading weed found in southern Manitoba, has long been listed under the province’s Noxious Weeds Act.

Until recently, it was classified as a Tier 1 noxious weed — the most serious level, requiring immediate eradication.

“Tier 1 means that the landowner or producer is obligated by law to eradicate every single plant that is found,” said Jenneth Johanson, District 5 representative with Keystone Agricultural Producers.

But as of June 20, 2025, the Manitoba government downgraded waterhemp’s classification from Tier 1 to Tier 2 in 28 rural municipalities.

“By moving it to Tier 2, you still, as a producer or landowner, are required to eradicate it if it’s under 20 acres. But if it’s over 20 acres, then the producer works more towards containment,” Johanson said.

The repercussions of leaving the plant untreated can be severe, according to Johanson.

“If waterhemp is left unmanaged in a field and nothing is done, it can overtake 160 acres within three to four years,” she said.

To control waterhemp, producers can apply both chemical and physical solutions — such as herbicides and mowing. In Johanson’s view, using both methods together is most effective.

“There are a number of different things we can do, so implementing all of these different components is what’s going to make us successful,” she said.