Knapweed can be colourful, but it's an eyesore for many farmers, as it's an invasive species that has creeped into the province.
Manitoba Agriculture weed specialist Jeanette Gaultier says spotted and diffuse knapweed have been found in the province, and other varieties, such as Russian knapweed, are nearby in North Dakota and Saskatchewan.
Gaulthier says knapweed does respond to herbicides, but often times options are limited.
"Unfortunately because (these weeds) are in pastures or along road ways, lots of times you have a lot less options available to you, but again, there are quite a few products that are registered that do have activity on it," she says. "I know even in Bird's Hill Provincial Park where they've had it, they've tried to go pesticide-free around the park so they've even had hand-roguing. So it depends on how big your patch is, as well."
Source : Portageonline