Answer: Iron deficiency shows up as chlorotic leaves - those with bright green veins and yellow or white tissues. If the veins are yellowing and then the entire leaf turns yellow, it indicates a need for nitrogen. I suspect your soil is acidic (based upon the amount of annual rainfall) so you might want to have the soil tested. If the pH is quite low, nitrogen will be bound up in the soil and unavailable to your tree. Once you have the results of your soil test you can adjust the soil's pH so it is between 5.8 and 6.4 which will suit your tree just fine.
Best wishes with your landscape!
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