Glyphosate mixed according to label instructions will kill it, and just about anything else. Tractor Supply sells their 41% concentrate for $10/quart. It may kill plants a little slower than Roundup brand, but at 1/3 the cost, I can wait. I found out last year that there is a glyphosate-resistant horseweed in some areas; unfortunately the horseweed around my place is the resistant variety.
