Note that anything nutritional, absorbed by any organism, moves throughout the organism (= "systemic"), in the blood or sap.
Spraying products labelled as fertilizers, with or without an adjuvant that promotes penetration, provides the plant with raw materials for use in all its parts and functions, including toughening of cell walls and other surfaces, and strengthening of systemic acquired resistance, and manufacture within the plant of plant-produced fungicides and bactericides.
Full-spectrum, balanced nutrition is best.
Calcium, Phosphite, Boron, Silicon, Sulfur, Copper, Zinc, and Manganese, are particularly useful for these internal functions. And if any of these nutrients/fertilizers, while still on the exterior of plants, should prove to be noxious to spores or other pests, no apologies are due to the pests or to anyone else.
Advice: Since products labelled as fertilizers don't usually come with much instruction or restrictions, and usually no safety data sheets, it is wise to study the labels and SDS of other products which contain the same declared ingredients, to follow the mixture rates and safety procedures that will keep things best for you, for the plants, and for the soil and environment. Avoid making any commercial claims of pesticidal efficacy.