sorry to cnfuse you no it is not pith but lynbga. We use 4 ozs ktea and 2 ozs reward (you might have to double) and mist over it, kills most anything it touches. This may not work in your water chemistry, but the 2:1 should. Or look at it atoher way it might take one gallon copper and 1/2 gallon Reward per weeded arcre and do the math. Test it out on a spot and see for your self, copper alone will take it from nasty brown to black but not killit.
