Sunburn. Probable cause not enough water during the hottest times. Shade cloth supported by some simple poles would help.

Wow. Exactly what John said. Also, I would recommend that your first fertilizer application be in late January or early February. That way, your first new flush should have some time to harden off a bit. I would definitely take with your ag agent, local gardening center or ASU about best times to fertilize to protect that young flush. I know you all have a great fertilizer product, "Arizona's Best" that is highly recommended by our AZ Citrus Forum members. Shade cloth, paint any exposed trunks or branches with flat latex house paint cut in half with water to protect your branches and trunks from sunburn. A badly sunburned trunk at this age of tree can be fatal.

Patty S.

Thanks very much!