Q.Why do the apricots fall off when they are about 1 inch.
I have oodles of apricots but they never mature.

Certified GKH Gardening Expert
This is a pollination issue. The tree will abort any fruit from flowers that were not pollinated. This has become an increasing problem with the decline of the honey bee.
These articles will help:
https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm
https://www.gardeningknowhow.com/garden-how-to/beneficial/creating-a-pollinator-garden.htm
Though it may be a pain, if you want, in the future you can hand pollinate flowers. You can use a small paintbrush and gently swirl it around inside each flower. This will pollinate them.