Answer: It sounds as though the leaves of your tree are getting sunburned. Yes, you can grow an avocado tree, but because of our temperature extremes, it may or may not produce fruit. Avocado trees need an eastern exposure, morning sun and afternoon shade to do their best in the Valley of the Sun. Avocados are a subtropical fruit so they prefer more alkaline soils, higher humidity, and less freezing than we can offer here in the Low Desert. However, there are Master Gardeners in Phoenix, AZ growing avocados.
You may want to check with folks at the Arizona Chapter of the California
Rare Fruit Growers Association for growing tips. There are contact numbers on their website:
Hope they can give you some handy hints.
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