I'm not sure about the first, but the second has a severe nutrient deficiency - prob Mg and Mn ...are the leaves pictured new or old?

I'd say the leaves are old(ish). The tree didn't put out a ton of new growth this year and most of that was in the early spring.

The first is fungal; give it a treatment with a good fungicide. The second is classic Mg deficiency and maybe Mn as well; I would guess your soil is high pH. Anyway a good citrus fert including Mg and Mn applied regularly should cure the problem.

Thanks! I've been buying a citrus fertilizer from Home Depot but I guess it's lacking in Mg and Mn so maybe I'll try Amazon? Is it better to go for a liquid, powder, something else?

Is there a particular type of fungicide I should look for? Is it for sure fungal and not citrus canker? I live in California and don't think we have that here, but I'm not really sure.

It's fungal, not canker. Most any quality fungicide will help. We use a systemic fungicide from Bayer (Silvacur, is what it is called here); I also use it for black spot fungus in my roses. If you are already applying a good citrus fert, you can just supplement with some Epsom Salt (MgSO4); I also put that on my roses a cupla times a year.

Looking at the leaves I would say the tree is deficient in Manganese and probably also zinc. In either case, when one treats for a manganese deficiency they should also always treat for zinc, and vice-a-versa. I don't really see a magnesium deficiency,

It looks like most palm tree fertilizers have manganese and magnesium - should I use these? As for zinc, I can't find a fertilizer on Amazon that has Zinc and Manganese....or really any zinc fertilizers.

I'll buy that one. Thanks! Anything I can do for the manganese and zinc deficiencies in the mean time or should I just let it be for now?

Somewhat related, are citrus-type fertilizers okay for guavas? I've managed to keep some guava trees alive all winter in the ground despite living in zone 8A. I've been using citrus fertilizer and they seem fine so far.