Large stands of avocado orchards around San Diego were not irrigated and died during the last drought due to the expense of water. A bit of a shame considering the time it take to get an avocado tree to produce. Some of the groves were also quite old and the land ripe for development, so that might have played into the decision of letting the orchards die.
I lived across the street from one of those abandoned orchards at the time. One 150' hose later, and the few trees I was able to rescue kept me, my friends, and my family in avocados for several seasons. Still miss living in that place.