I posted this elsewhere, but it might be worth repeating here. I see some folks talking about Sonar. This stuff is STRONG, so be careful. I had a "professional" treat 16 acres with it because of a bad coontail and duckweed issue. I didn't know yet what to do, as I had just bought the land, and I didn't have any equipment for applying anything yet. I even had him scale back the amount, because I was afraid of overkill. It did the intended job. Boy, did it! Coontail and duckweed were gone a few months later, as were pretty much all other weeds and grasses. It killed lillypads, cattails, everything. THEN, the lake froze over in what truned out to be a long, hard winter, and there wasn't anything in the lake to make oxygen. We had a pretty substantial fish kill, and lost thousands of bluegill and bass. Populations are recovering (fish and weeds), but you have to be VERY careful with herbicides this strong. If I had it to do again, and I might eventually have to, I'd use about half or so, and reapply later if need be.
