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Weevil for knapweed? #873223

Asked June 15, 2024, 12:27 PM EDT

Hi! I'm wondering your thoughts about using this weevil for spotted knapweed: http://www.weedbustersbiocontrol.com/knapweedinsects.html?gad_source=1&gclid=CjwKCAjw1K-zBhBIEiwAWeCOFx_Urb-J6Pxlj6rkBXiyKCVgrf5SVvDWeMXOCydSrbKv8FXW6JgP9xoCoqkQAvD_BwE I've never really been too mad at the knapweed in this area, but my new property is very clay-y, has pretty steep hills and erosion is a problem following our construction project. We have been pulling them manually bc they are making a few spots inhospitable.to other plants (I think that's what's happening...?) But the problem with pulling them is that it makes the ground even more erosion-y. I was thinking that it might be better to use a weevil to control them a little, but it would leave the structure & organic matter in the ground. Buuuuut, I'm worried about introducing something exotic/invasive. Any advice?? Thanks much!

Leelanau County Michigan

Expert Response

Thank you for reaching out and our apologies for the delay in responding.  Your question has been assigned to an expert but in the meantime, here's a terrific article you might find helpful--particularly towards the bottom there's a link to an article from Montana State University:
https://www.canr.msu.edu/news/drive-by-botany-purple-loosestrife-and-spotted-knapweed

Best wishes,
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Hello,

I am not familiar with the Knapweed weevil, so I reached out to the Michigan Department of Agriculture and Rural Development and left a message with one of their pest and pest control experts. First I asked if they are familiar with the use of this weevil, then I asked if they are effective at controlling spotted knapweed, and finally I asked if they are allowed in Michigan. 

Can you please email me (<personal data hidden>), so that I can follow up with you?

Thanks!

~Erick

An Ask Extension Expert Replied June 28, 2024, 10:56 AM EDT

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