Three of the garden beds are infested with Canadian Thistle. After a bit of research, I decided to bite the bullet and hit them with RoundUp. The rhizomes need to be killed, or the plant will never be eradicated. I sprayed the thistle in the three beds and some other random plants around the garden. I also sprayed a bunch in the blackberry patch. I waited three days and then hit the plants in the bed with the weedwhacker. I am hoping it minimizes the spread.