Avocado tree appears to be dying.

Question

My avocado tree is looking very sad. It has lost many, many leaves, has drooping branches and many branches with absolutely no leaves. I have fertilized, watered and and seen no improvements. It gave us many small avocadoes this year, about 3 grocery bags full. Should I prune those branches with no leaves or leave them on the tree. Help me save the tree. Here is an image of the tree.

Answer 1

The most common reason for decline like this in avocado trees in the Bay Area is over-watering resulting in root and crown rot from the pathogen Phytophthora cinnamomi.
If the tree receives frequent irrigation from a lawn area or other landscape plantings, then you have to decide on which to sacrifice. The only way to save it, if it is not too far gone, is by stopping the frequent watering and let the soil dry out. Then water deeply but infrequently. There is a systemic fungicide available, which is used on commercial avocado orchards, but this is best applied by a professional.
Monterey brand Agrifos with Pentrabark is available in some garden centers in a combo pack to mix in one gallon of water, to be sprayed on the lower tree trunk for absorption and uptake into the tree tissues.

There are other possibilities as you will see in the following article.

https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-pests-and-diseases.htm