 When you spray a foliar fungicide, there are two big things to keep in mind. The fungicide will only protect the leaves that you spray, and the fungicide can only move upward in the plant, usually just within the same leaf. Zyway, which has the same active ingredient as Top Guard, is just like any other fungicide in that it only moves up. However, when you put Zyway in furrow, there's pretty much nowhere else to go but up.