You should just apply calcium and copper. You probably need both to get into the plant. Just make sure it is a neutral charge or it won’t get into the phylum of the plant. Fungicides are just another expense that the chemical guys love to sell, because it doesn’t work.  I’m Here to tell all of you that soon fungicides will be outlawed, along with NH3.  Then what will you do? First thing is getting the dirt changed back to soil.