Sounds like Triclopyr (Arsenal). That has a good bit of soil activity and a long half-life so it stays in the soil a good while. It will kill for sure
But, it keeps on killing and kills the desirables plants also. If you want a hole, that will sure open up a hole
Not against herbicides by any means, I try and kill every tallowtree there is.
BigPond, I don't know about Miami Corp, but I am curious as to if they would allow herbicide spraying. If you find out, please let us know. Cattails and sawgrass are not preferred duck forage, but what they do provide is cover and a source of invertebrates. The late season is when this may be crucial as ducks are getting as much protein as they can getting ready to head back and make more duckies. You have probably witnessed late season ducks land in the thickest cover they can find.
You could prevent cattails if you had a way of controlling the water on your place. A drawdown would keep the cattails at bay and let the other desirables sprout.
Your cheapest bet may just be to get out there with a weedeater and open up a hole right before teal season and then again before big duck season and/or get a mudboat or airboat in there to keep it down.
Good luck, keep us informed