Avocados bear heavier crops on alternate years. If the tree is healthy and the fruit is good, wait until next year to see if the crop yield improves. If there are other symptoms of pests or diseases, review the Avocado Problem Diagnosis Chart.
Read more about avocado trees, including fertilization, watering, harvesting and pruning.
When is the fruit ripe
It is hard to tell from the outside when an avocado is mature. Commercial growers conduct a "dry weight" test which gives an indirect measure of the oil content of the fruit. If the oil content is too low, the fruit is not ripe yet and will shrivel or stay rubbery instead of getting soft.
What you can do at home is pick a couple of fruit and try to ripen them. If the fruit shrivel up or seem rubbery instead of soft, they are not mature yet. Keep picking fruit every few weeks. Note on the calendar when they soften instead of turning rubbery. Also note the taste of the fruit. The oil content of the fruit usually increases through the season and there will be a certain point when it tastes just right. That date will usually vary somewhat due to climate conditions, and some years will be better than others. Some varieties can also reach a point where they have too much oil and some will turn rancid, although many types fall from the tree before reaching that point.
The Hass avocado typically ripens in February and is good through June or July. These dates depend a lot on where you live and climate conditions. Some years you can pick larger fruit as early as December and they will ripen up. In Ventura County, fruit can remain on the tree and still be good into August and September.
Varieties that ripen other times of the year (dates based on the experimental plot in Irvine, CA):
Reed: June - Sept
Pinkerton: Nov - Jan
Fuerte: Dec - March
Lamb-Hass: May - Aug