duck weed in pond

[Antonia]

Does anyone know how to organically control duck weed in old, unused by cows stock ponds? It's not algae. I tried corn meal which made it worse. The entire surface is green.

Thanks, Antonia

[pat mcKennon]

I know what you mean! We used the cornmeal and also tried spraying hydrogen peroxide. (my family thought it was algae at first). We have probably lost ALL our fish in a (heavily stocked) pond and stream. All my searches indicate that there are two very expensive (toxic) chemicals: one called Reward (Diquat)--costs $90-150 a gallon--the other is even more expensive. Copper Sulfate is supposed to kill it out to some degree and will kill the fish, too. We're thinking about using the triploid (sterile) carp which will help some. None of the information I have read is very encouraging--especially when you have treelined streams which don't flow much! We also get a lot of runoff from other peoples's heavily fertilized grass fields. I'm wondering if there is an acceptable material to tie up some of phosphate or organic matter in the tank and stream somewhat like Nored can do for chemical spills!
Good luck! Please let me know if you come up with a more "organic" control than the chemical one!
Jeanette McKennon
<egglady@wf.net>

[Antonia]

Yes Pat, I've seen the same info on the web. I visited a water garden nursery this past week end. Their only suggestion was the native carp, which are not sterile, and would live through a Dallas area winter. My husband found more info which stated if the carp found a plant they prefered over the duckweed that's all they would eat. I still may try the carp.
Antonia

[Photobug63]

Well I know that goldfish don't eat much duckweed. If you can't get
sterile grass carp try getting carp from your area and hope it might
eat it.