Deficiencies or fungal pathogens issue?

Was listening to a growing podcast and the question came up how to tell a deficiency from a harmful fungal pathogen? Both show similar symptoms. This is where it gets cool. So fungal pathogens are related to moisture we know this so when you see the dark spots with yellow ring around them look to see where in the leaf it is if it’s a deficiency it will skip the veins of the leaf if it’s a fungal issue it overlaps the veins where the water is pumping threw. This opened my eyes and hopefully helped someone else. Have a great day portal fam