My uncle has a number of apricot trees he grafted himself onto some sort of wild plum rootstock. They are between 5 and 10 years old and quite large. Every year they produce tons of flowers but all of the fruit drops off green.

Of the 5 to 10 years he's had these trees they've produced exactly 3 apricots which were able to ripen.

The trees have never been sprayed, they're planted a little bit too close together and aren't pruned to an open center or anything like that.

There are no other varieties of apricot around to cross pollinate. I know having another variety helps with pollination however apricots are in general self-fertile so this shouldn't really be a huge problem.

He does have some wild plum around which I have heard is possibly able to help with pollination but I don't know for sure.

This year I am buying him another apricot tree to hopefully help with the pollination in the next few years.

However, I was hoping for someone else's opinion on what the most likely cause for the fruit drop is.

Thanks ahead!