New strategy for attacking Canada thistle in Crellin Meadow

Renee Popp at Crellin Meadow 8/19/09 Note lack of Canada Thistle flowers
Renee Popp at Crellin Meadow 8/19/09. Note lack of Canada Thistle flowers (click image to enlarge).

I asked GVM resident Renee Popp, what her thoughts were on controlling the noxious weed, Canada thistle (CT). As field botanist of over 30 years, both with the USDA Forest Service and as an independent contractor, Renee is an ardent supporter of noxious weed management as a way of improving habitat for our rich store of native plants. This season Renee had a break in her field schedule that allowed her to implement a plan she has been wanting to try for 10 years. On 9/1/09 she wrote:

“Many times I’ve seen the County and now GVM come spray Crellin Meadow (NW of Crellin Lake) where I live, sometimes twice per year. And every time the CT sprouts right back like nothing happened. I think that’s because the treatment is too little too late.

CT operates from an extensive underground root system. To get CT on the defensive, the roots’ reserves need to be compromised if not wholly exhausted. A 4-wheeler with a boom to apply herbicide works great on flat farmlands. However, in the case of Crellin there are trees and wetlands that prohibit a 4-wheeler from making clean sweeps with complete coverage. These obstacles result in pockets of the infestation left untreated. Any plant that is green and photosynthesizing is sending nourishment to the roots.

This year I checked out a spray canister filled with Milestone provided by the GVM office. I spot-sprayed everything that GVM’s 4-wheeler didn’t get. And when a single sprout came up, I sprayed again and again and again. I’ve been re-spraying every week to snuff out new sprouts. It’s been held down long enough now that I expect to see some difference next year.

I realize that the CT population in Crellin Meadow is most likely here to stay, but I still believe we can slow its spread and reduce its size. For this reason I emphasize finding and spraying plants at the outer boundaries as a first priority on this or any other CT infestation.

In the end I guess the message for CT is that intensity may be more important than extensivity. Strategic, complete, high frequency, and targeted hand-spraying may be the keys to reducing and even eliminating weeds vs. just living with weeds and herbiciding broadly forever.”

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