Twelve years ago our 14 acre farm pond went dry because of a hole in the spillway under the dam. Once the spillway was repaired it took another summer and a tropical storm to fill the pond back with water. The cattails had completely covered one third of the pond. We started spraying Roundup with a 15 gal. battery powered sprayer. Every two weeks we would go out and spray. By the end of the summer we had the pond completely clear of cattails and other weeds. There were still dead canes, but every time any green blades appeared we would spray them. We have in the past burned the cattails, but they came back greener and thicker after the burning. With generic Roundup, we have completely eliminated the cattails. We are having issues with underwater weeds that the Roundup will not kill. I had people telling me I was destroying the frog population and I may have. However the frogs seem to be doing fine now. The fish are also doing well.