Amaranthus tuberculatus , commonly known as waterhemp, is an aggressive weed known to have resistance to multiple herbicide groups and it is of growing concern in Manitoba.
In June of 2025, Manitoba Agriculture announced a regulatory change to The Noxious Weeds Act and they have now downgraded Waterhemp from a Tier 1 to a Tier 2 noxious weed in certain Rural Municipalities (RMs) across the province.
Based on the current distribution and establishment of waterhemp and by consulting with industry associations, it was determined this change would aid in limiting the negative financial impact on producers whom otherwise would have lost extensive agricultural productivity in requiring the destruction of waterhemp on areas larger than 20 acres.
According to subsection 3(1) of The Noxious Weeds Act, if a weed is classified as Tier 2:
- Destruction is required for a weed colonization of less than 20 acres.
- If the area is more than 20 acres, the weed may be controlled rather than destroyed.
- The updated classification enables the following municipalities to focus on containment and control rather than eradication:
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