Yes Imox works on smartweed. I used it this past summer , killed most except goldenrod which isn't on the label. Would've worked better if done early spring I think, and we were in middle of major drought at the time and that hurt results sometimes. BTW, cleth is great on grasses but does not touch sedges. But I'm guilty as charged, my fields are in need of lime for the first time in 10 years but wet 2018 and spring of 2019 kept truck out of fields. Normally I wouldn't have used and have never used in 10 years of plotting, such a strong and expensive herbicide. It does the job, but if only we analyze reason for a so-called weed, or if its presence is really a problem long term, then time and money can be better spent. I maybe have said that a few thousand times, perhaps I should listen to myself.
And while I wouldn't want an overabundance of sedge, deer do browse on it some. And if you look close, clovers will actually be thick within a grass clump, making me think the two help each other. I know, blasphemy for the food plotter but observation can teach a person a bunch. Good luck in those mountains, certainly a different ballgame speaking from experience.