Copper Sulphate (CuSO4) Solution as a Fungiside ?

[Ray]

I think the important part is the elemental copper, which in copper sulfate pentahydrate, is 25.975%, making Physan 25.975% of 213.6 or 5.54%.

Whether copper sulfate, copper acetate, copper hydroxide, or whatever other copper compound is used, it's the copper concentration that's important.