You will need a systemic herbicide to wipe out the root system- the pads will need to absorb the chemical. The root system on these are quite extensive and normally embedded in the pond bottom fairly well.
As Greg's team recommended, for ease of application whitecap is a good alternative, and cheaper than sonar. It will wipe them all out. I have done spot treatments using Habitat (1% solution) with a good surfactant mixed in, and some dye so you can see where you've sprayed. Can do with a backpack sprayer as long as it has aggitation. Habitat runs about $250/gallon.
www.qualitylakes.com"If once [the people] become inattentive to the public affairs, you and I, and Congress and Assemblies, Judges, and Governors, shall all become wolves."
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