Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Southern Naiad

I am the president of a 22 acre lake in upstate SC. The last 2 years southern naiad has appeared around Memorial day and taken over our lake/pond. I have spoken with the local Clemson agriculture officer and they recommended using a copper sulfate additive to be administered by a professional pond management company. In addition to this we had a pond pro out to talk about dumping some lime in the lake as the ph is a little low. He said to just continue adding grass carp (we added 300 back in the spring) to handle the problem until they caught up.

Now I am asking you guys, who is right here? I know the copper sulfate additive will work but its 5-6K to do that and there is no guarantee that the naiad will not come back.

Welcome to the forum. Couple of questions:

What are the largest sized Largemouth Bass (LMB) that are in the lake, and what size was the Grass Carp (GC) that were stocked?

FWIW, typically the first year that GC are stocked you don't see much weed control. They are "getting their bearings" so to speak. Niad IS on their "preferred plant list", so they will control it.

The largest bass in the lake are probably some 5-7 pounders that were stocked some 10 years ago. All the rest are less than that. There could be some bigger than that but I have not seen them.

The carp we added were the largest available and about $12 a piece. Right now we do not have the optimum 20-25 carp per acre. Would it be a good move to add more now?

I might be outta line because I haven't seen the lake, but I think that if all the fish that you stocked survived predation, you have enough per acre. The key is survived.....

http://jmmaloneandson.com/TriploidGrassCarp.html

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.

We are using a professional aquatic applicator that has been in business for 45 years, so I will assume he knows what he is doing and what's best for our lake. Assuming all grass is killed and the carp we put in can then begin to control things somewhat, what can we do to cloudy up the lake to try and prohibit the Naiad from starting up again?