Commented: Avocado tree problemYour photograph shows evidence of persea mite infestation. I'd hold off on the fertilizing right now; excessive nitrogen can increase your damage.
Commented: New avocado trees: will what I want match with what will work?This space would permit but two avocado trees and that would be after increasing both the length and width of your plot. They may block your neighbor's ability to receive sun in their side windows aft...
Commented: Yosemite gold mandarinGreen Thumb Nursery has carried it for years; both 5 and 15 gallon. They have a few locations including Lake Forest and Canoga Park.