Another quick kill option for curly leaf pondweed (CLP) is to use a brand of Diquat 37%. READ and understand the instructions. I regularly use it in my pond and it works good when applied timely and appropriately. If you do it correctly you should see die back results in several to 10 days.
Note - if there is a huge biomass of CLP that you are quickly killing, there could be a significant DO sag and maybe a fish kill? Be watchful.
If treating the whole pond use bottom aeration to help mix the diquat throughout the pond.
Herbicides work best for CLP before it has reached the surface, formed flower buds, and not yet formed turions in the axils of the leaf. You being in MI,,,, turions should not have formed as of May 03. Turions are dormant buds that develop in leaf axils (the "joint " or space where the leaf stem and the stalk of the plant come together), or are present at the tip of short branches. They are made up of several overlapping modified leaves resembling small greenish-brown pinecones, and are produced in great numbers by the start of summer.
Turions that have formed before killing the CLP will sprout this Fall and the next spring for producing CLP in future years requiring more annual treatments. IMO you will likely have to do some form or retreatments in the upcoming years. I do some spot treatments for CLP using diquat sprayed using a long wand into the clumps of CLP. CLP is a definite early season pest.
IMO do not use the 'weedtrine' that is a diluted form of diquat and requiring more jugs to deal with.
Last edited by Bill Cody; 05/03/25 09:45 AM.
