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Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Sunday - September 07, 2008

From: Rapid City, MI
Region: Midwest
Topic: Non-Natives
Title: Invasive, non-native Cirsium arvense in Michigan
Answered by: Barbara Medford

QUESTION:

I have identified that I have growing abundantly "Canada Thistle";the noxious and invasive. I know this to be true because where it grows nothing else grows; not even the native weeds. I want to get rid of it!!!!! Can you direct me as to how I may do this? I have tried pulling it out before it seeds; burning it and cutting it down and it always seems to return in a vengeance!!

ANSWER:

We do sympathize, that is one nasty weed. However, there is no magic formula for getting rid of it. Refer to this Plant Conservation Alliance Alien Plant Working Group paper on Cirsium arvense for some  information on the plant. As a non-native plant, it doesn't fall into our ordinary realm of experience at the Lady Bird Johnson Wildflower Center, but as an invasive, we are certainly interested in controlling it. The plant is native to temperate regions of Eurasia, and was introduced to North America, probably accidentally, in the 1600's. Another resource is this University of California at Davis website on Canada Thistle, with instructions on identification and control. We neither recommend for nor against use of pesticides, and urge you to use them with caution, following the directions carefully. One of the points that site made is that it can be more damaging in cooler parts of North America, which would include Michigan. We wish you well in exterminating a really bad pest.  

 

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