Well its now so out of control we are going with a copper sulfate/diquat combination to help the carp out. Has anyone got any experience going this route?
Hopefully, you're referring to a copper-based (chelated type) herbicide and not copper sulfate. If so, that's one of the viable options IF administered judiciously.
If you attempt to gain control too quickly, especially at this time of the season, you may be successful in controlling the weeds - maybe too successful, and cause an oxygen-crash. It happens all too frequently in mid to late summer when weed biomasses have peaked and DO-levels are already on a roller-coaster ride.
I'd recommend using the services of an experienced application professional who knows what he's doing.
