I have two old avacado trees on my land on the SW coast of Mexico (probably zone 11). One year yields lots of fruit, the next almost nothing. Are they biennial? Also, some years find all the leaves have fallen off...other years they stick around. Ideas? or better yet, facts?
I've nver experienced Avocadoes to be biennial, but when the tree is very old it may start to be - it's a conservation of energy thing. Once they hit about 80-85 years old, they stop producing edible fruit altogether. Periodic leaf drop is very common with mine, but since the leaves always come back, it doesn't worry me so much. I figure it's sort of a whole-tree rejuvenation thing - all new leaves. Do you find that your fruit set is heavier the year after the leaf drop?
You'll be just fine, then. Once your younger trees reach bearing age, the pressure won't be as heavy on the older ones to bear fruit every year, and they can settle into a comfortable maturity. (I know this sounds odd, but if you let your trees know that they're not under pressure, they won't kill themselves trying to set fruit for you. This kind of compromise worked wonders on a couple of my older citrus trees, not to mention the mulberries and my pair of centennerian avocadoes.)
