This post is from Marc Davison, superintendent of Green Bay (WI) Country Club, and major Chicago Blackhawk fan. He has been trying to control Horsetail (Equisetum arvense) and Milkweed (Asclepias syriaca). Neither of these weeds can survive mowing for long in maintained turf and there is not a lot work on their control in turf areas. In no-mow areas, however, they thrive. Mark has been experimenting with various herbicides and has found that Garlon (triclopyr) from Dow Chemical is doing the job. He uses 2 oz per gallon of water and spot treats the target weeds. He is still working on Rough Horsetail (Equisetum hyemale) a related species and will let us know now it works. I grew up calling horsetail (puzzle weed) because its stem can be disassembled and put back together like a puzzle. Some of you may recognize that name.
The picture below shows the horsetail turning white and the leaves of the milkweed turning yellow.