I don't know of any granular herbicides that are effective. Liquid? Yes.

American Lotus will grow to USDA zone 4. I don't think it matters whether it's lily or lotus, but are you sure it's lotus? Lotus does not have a cleft leaf, lily does.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).