What content ratio is best to use to help the tree resist the disease?
Verticillium Wilt in a Tree and High Phosphorus Fertilizer
Certified GKH Gardening Expert
I would say that a better way to manage the disease, and prevent problems would be to use wettable sulfur. That and a little dolomitic lime to regulate pH. Phosphorus will raise the soil pH, but it will not, necessarily, kill any diseases on its own.