Pond Boss Forums Thread Like Summary - Curly-Leaf Pondweed

I have a small 1/4 acre pond that is being taken over by curly-leaf pondweed. This is the first time in 10 years I've seen this weed but it's spreading fast. We have three grass carp in the pond but they don't seem to be eating it.

Is there any way to control it without chemicals?

ZTrain - There are granular aquatic herbicide brands including 2-4D formulations that can be used for spot treatments by just spreading the correct amount of product in a specified area. I and others here have also used liquid diquat brands such as Reward and Harvester that are likely what are used by the 'professional' applicators that are hired by the HOA. These liquid formulations can be used as spot treatments by injecting the mixed solutions underwater into areas with curly leaf for good results in sections of a pond. Good injection methods and even coverage into treatment areas are important for best results.

If the curly leaf in your pond seems to returning as abundant or more of growths each successive year then IMO the professionals are not applying the herbicide early enough in the life cycle of curly leaf. Chem-kills for curly leaf should be applied before the plants form turions and seeds. Turions and seeds are how the plants repopulate the pond each year. Good effective efforts of annual kills each year should gradually over time reduce the amount of redevelopment of curly leaf that appear each year.

I cannot speak to others situations, but introducing papershell crayfish solved my issue with curly-leaf pondweed.

Just thought I’d give an update to anyone interested. I did my first attempt at spraying last weekend. Sprayed 2 tank fulls (2 gallon hand sprayer) of a mix of Diquat and cutrinePlus. I think I did 8 ounces of Diquat and about 4 ounces of Cutrine in each tank.

Because I was getting to the spraying late (due to a combination of getting slow response from Neighbors on the pond about being ok with me doing treatments, and due to weather (windy, cold, cloudy days that weren’t good for treatment) the weeds had already gotten pretty thick in some areas and reached the surface fully.

I sprayed those mats along the shore about 1/3 of the pond. I’ve been checking to see how they responded. It appears there was some impact at the very surface, but underneath the weeds still seem to be growing.

I sprayed again this morning, on a different section of the pond, with an increased amount of Diquat (approx 12 oz in a tank) and also with non ionic aquatic Surfectant added. Will monitor and see how this goes and see what I should try next.

From my reading it seems like the issue I’m going to run into is that since the weeds already reached a matted level, it’s going to be difficult to get the spray down deep enough into the water column to really kill them. I saw mention of dragging underwater hoses to describe spray deeper. I don’t really have any capability for that since I’m just using a hand pump sprayer in a canoe…

Anyway, we’ll see how this second spraying goes. Trying to be careful and not accidentally kill too much at once and cause any issues with the fish in the pond. So would rather mess up on the careful side and have the weeds grow more than I’d like, than go overboard and kill fish.

That's the nice thing about Fluridone, just dump the correct amount in the pond and walk away. It kills the weeds over a 30-45 day period. You have to treat the whole pond at once though. The dosage that kills the CLPW won't affect other native plants.