Not sure what this is, I know the pics aren't great, but whatever it is, is on several of my trees. Would hate to buy more trees if its something that could infect the others.

Here are a few of the pics. It looks like old rusty water spots. the leaves thin and dry out in the area of these spots. some are in the edges, others are in the middle of the leaves. I've picked off most the infected leaves, just the one tree doesn't have many leaves so there are still a few









any help, suggestions GREATLY needed! it started off just the odd leaf but more are getting it. not sure if it could be salt buildup or over fertilizing or if I have a desease/pest

At first glance, those seem like fertilizer burns to me. This could be due to applying too much fertilizer like foliar. Also if you have water droplets forming on the leaves and drying, it could cause those spots if your water is loaded with minerals.