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From tree experts at New Mexico State University, they say that first is to keep trees free from bugs and insects. Second is your climate and weather. Certain places will not help the tree and will not produce fruit. Pollination is next as the tree needs that in order to produce fruit. Also needs full sun.
Hope this helps.
Thank you for the advice. I could say "none of the above". The tree is very healthy. Where we live, the weather is perfect for fruit trees ( I have several other fruit trees such as peach, pear, persimmon, citrus, etc. ). They are doing excellent. This particular tree was purchased from a nursery (now de-funk) told me that the seed is eatable while other's are poisonous. As for pollination, there are honey bees around during Spring. I tried not to pruning and let it bear fruit on the previous growth. No luck. May be it is the trend. Wonder what is the annual amount of production of apricot in California, I wonder.
The site I found info on care of fruit trees does say that the plant should be healthy from the nursery. I have tried myself using fish fertilizer for my grapes and plum tree and that helped in getting fruit started. Since your tree is older, I am not sure if that will help. Might give it a try.
As for production of apricots, here is a great link to everything in terms of production in CA:
I wish you luck in getting some production from your trees. Please rate my answer so that I can receive credit for helping with your interesting question!