Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Selectively killing large woody invasives only

NW Louisiana-
I have what I call giant lilly pads ataking over a large 200 acre lake on one end, and what i call water hyacinth doing the same on the other.
In between are great (duck food) species of coontail, milfoil, wigeon grass, and other mostly submerged plans I must keep.
In theory at least, is it possible to selectively kill with chemical, the large woody species like the lilly pads and water hyacinth but not harm the good stuff?

I've tried to reach out to the local LSU Ag extension office but haven't had much luck.

Welcome to PB! that's a tough one, I know painfully little about your question but will comment on here to push it back to the top, hopefully one of the resident professionals on the subject will notice it and respond. Good Luck!

Who owns the lake? May need to get permits etc. You could contact a lake service. Careful hand treatment of lilly pads can work (glyphosate with aquatic surfactant). Could be very labor intensive.

I agree. If it's a public Body of Water, you will most likely need permits. I would use either a a glyphosate based herbicide or a Triclopyr based herbicide plus a surfactant AND a pond dye as a marker to see where you sprayed. Spray only to the point where the herbicide starts to run off the plant and no more.

Follow the directions on the bottles as to the application rate per surface acre.

Triclopyr based.
Good idea! Double check but I think you can mix with glyphosate for a combo punch. I used it on phragmites once with strong results.

I am NOT an aquatic vegetation expert!

However, I have been very impressed with the selective herbicide targeting of some of the products I have used recently.

For example, I sprayed a few gallons of Crossbow (2,4d with triclopyr) this summer on some bad poison ivy areas. I went back and checked results 8 days later. The poison ivy was all scorched to death - and the eight varieties of prairie grass that I also sprayed were showing no effects at all in that time frame.

Crossbow is designed for woody species in permanent grass pastures. If your targeted aquatic plants are truly "woody" species, and your desirable plants are not, then you might have a chance of selective treatment - with the right product.

** I do not know the proper classification of your targeted aquatic plants versus the desirable plants.

*** Crossbow is toxic to fish! (I think due to the 2,4d component.) My point is that you should keep searching (and perhaps spot testing) to see if there is a product that will perform the selective treatment you desire.


Good luck on your project!

2,4-D is the active component in some aquatic herbicides. The plant species mentioned by the original poster are not considered woody plants.

https://www.shorelineaquatic.com/24-d-aquatic-herbicides-for-lakes-and-ponds

Spot treating with an aquatic formulation of glyphosate (like Rodeo) might work following the label instructions.

RAH,

Thanks for the clarification!

I wasn't sure the OP's targets qualified as "woody" plants.

I also find it odd the some formulations of 2,4-D are approved for aquatic use, and some formulations of triclopyr are approved for aquatic use, but the two combined in Crossbow are labelled toxic for fish. (Regardless - I am not going against the label instructions for any herbicides that are that deadly!)

Sometimes the the formulation ingredients, rather than the active ingredients, are toxic to aquatic organisms.

Like RAH said above, it could be the surfactant in the ingredients that is not rated for aquatic use. An aquatic approved Triclopyr is Renovate. An aquatic 2,4-D is Navigate or Weedar 64.