What’s The Best Aquatic Weed Killer

We get this question a lot: What is the best aquatic weed killer? That is a great question, but unfortunately, it is not that simple. It is sort of like asking: What’s the best saw? Aquatic herbicides, like saws, have different purposes, and work on different weeds. Just as there are small thin perfectly tuned little dovetail saws for meticulous and extremely accurate work, and chainsaws for very heavy rough work, one lake weed killer may be made for getting rid of submersed thin weeds, and another may be specifically formulated for large broad leaf plants above the water level.

There are some aquatic weed killers that do many jobs, for instance, contact weed killers like diquat (Reward) destroy any plant tissue they come in contact with, but only the material they come in contact with. If you are treating an infestation of annual weeds, this will work well. In fact, diquat may be the best overall aquatic weed killer on the market for submersed and emergent weeds, if you pay close attention to the follow up process. See: Lake Management Lake Weed Control Water Depth Secchi Depth

If the weeds you are trying to rid your pond of are perennials, a systemic aquatic herbicide like “Rodeo” or 2,4-D may be more appropriate. Even within this distinction there are limitations. 2,4-D works well on lily pads, but is restricted in some areas, and for some purposes. On hot still days, it can volatilize and float off target. Glyphosates, no matter how much surfactant you use, seem to bead on waxy plants like water Lillis, and don’t work as well. Glyphosates work very well on both broad leaf and grassy weeds in general, as a general purpose non selective systemic herbicide, but they can’t kill what they can’t penetrate.

In short, you need to know the weed and the conditions before selecting an aquatic weed killer. Aquaplant is a great little tool for plant identification, and for choosing the right method of dealing with it, including the best herbicide for each plant.

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