Liqui-Cop is copper, which is effective as a dormant spray type of product, if that is what you are after. It would be considered more of an "organic" treatment than a fungicide such as Banner Maxx, Bayer Rose & Flower spray, that type of product.

Copper in that form works fairly well as a "contact" type fungicide -- it kills whatever fungus it comes in contact with while it's still wet. When/after it dries, I don't think it has any effect, which is true of most of the "organic" fungicides -- contact only/no residual effect, but they kill what they touch.

I use it occasionally, but I don't like to use it during the growing season because it leaves blue spots on the leaves, which I find ugly. If you don't mind blue spots all over everything, it's fiine. Wear old clothes when you apply it, again, unless you fancy blue spots. The main advantage copper has over other fungicides is its cheap price -- most everything else is five to ten times as expensive, if not more than that.