tyan, here is what works in our Ohio Ponds for spadderdock (cow lily)AS a preventitave strike I prefer Fludidone at 90 ppb or in most water depths less than 8 average 1 qt per acre.Then hit any escapes with Aquatic 24-d like Weedar 64 and Aquatic Gly with a non ionic surfactant.This mixture works well.Coverage and rate being key.If you have lots of them use caution with the 24d and Gly approach and be sure to only do 20-25 % at a time without aeration.With Fluridone the kill is slower (but probably just as complete) Be aware of all the water use restriction for all of these products.You might consider calling a pro such as Greg Grimes who probably works your area.Find him in the "Resource Guide"
