If there's a yellow ring around a dark spot it's probably septoria, yea. That def looks like it. One more rapidly growing plants you'll just see yellowish leaves in odd places on it, spots coming in once turgidity is being lost on the tissue. Often newer growth too. Until this year I had only ever heard of septoria, hadn't actually seen it but very rarely, and was never sure. This is all def septoria over here. It's on literally everything in the old man's yard. It's even on the grass
Sapsuckers and direct contact can spread it iirc
I'll be cutting down my apricot shade tree next to my patch soon, it's breaking out in septoria and the leaf fall is starting sooner then normal and it's already given it to my current biggs phenotype
There's new hyper virulent strains of powdery mildew this year too that I've never seen before too down here in the valley.