Hi all,

I have a one acre pond in Ontario Canada that is filled with Curley Lead Pond Weed. In the last few weeks it has grown out of control. We have tried putting dye in the water that we purchased at a pond store but it has had little effect. We put it in before the weeds grew up but it didn’t seem to stop them. We have also tried raking the weeds with a weed razor but it takes lots of time and we fear they will just grow back. We are looking for a way to control the problem as the pond is used for swimming. The pond is stocked with trout and has many other beings such as: turtles, frogs, crayfish etc. We don’t want to kill any thing if we don’t have to. The pond has a surface arrerator but maybe it’s not enough. Any suggestions would be greatly appreciated.

Weeds touching surface: http://imgur.com/p2NThEQ
Fontain: http://imgur.com/pzKrWGK (photo from last year so no weeds)

Thanks,

Adam

Curly leaf pondweed is definitely problematic. It emerges in late summer as young sprouts then overwinters on the bottom as short plants. When water warms in spring it rapidly grows toward the surface as it forms prolific winter buds that as the plant dies back, buds fall to the bottom for the late summer re-emergence as new shoots from the buds (turions). The cycle continues. As you mention manual removal is time consuming and hard work. Curly leaf is vulnerable to proper concentrations of a few aquatic herbicides. Slow acting as low dosages contain fluridone such as Sonar and Avast. Also effective as rapid burn down herbicides that contain diquat such as Reward, Harvester, Tsunami and a couple other generic brands. There are granular spot treatment herbicides that kill curlyleaf. Be aware all of the treatments will generally need to be repetitive in successive years because the turions will sprout over the course of the next few years and the chemical treatment usually does not kill every plant in the water body. A few remote curly leaf plants manage to escape by being in some sort of aquatic refuge area. Also reintroduction by natural methods seems to occur especially when the specie is growing in nearby waters.

Thanks for the info. If I use the products you mentioned will my fish and other pond inhabitants be effected?

If you use the products as directed on the label fish will have very little impact. Main exception is if in warm water you kill all the weeds at one time and the bacterial decompostion lowers the dissolved oxygen to concentrations to stress the fish. The curlyleaf should be killed in early spring or fall when water temps are 50-60F and prior to formation of turions.