Arrested peach development

Question: I have a strange peach situation that I am hoping you might be able to provide some information.  I have two peach trees in a small orchard.  I do not know the variety off hand, but I might be able to find out.  I planted them 5 years ago.  They get identical treatment, from pruning, fertilizer, etc…..

They bloom, set fruit on the same schedule.  Then when the fruit are about 1-2 inches and green, one tree just “stops”.  No leaf curl, no obvious pests, nothing seems to separate  the two trees except the one stops the ripening process.  As of now, I am getting hundreds of peaches from the one tree, but the second sits at the green 1-2 inch stage.   Eventually, as the nights cool and the days shorten (October), these green fruits will ripen, stay very small and are mealy/gritty.  Do you have any insight?

Answer: If a peach tree has way too many fruit, this will greatly slow ripening and sizing.   However, if there is not much difference in the fruit numbers per tree, then the reason is probably genetic.

Probably most likely is that the scion (the variety budded on top by the nursery) died and the rootstock sent up suckers which eventually developed into a fruiting tree.  One of  the common rootstock types, Bailey, ripens very late and has tiny white fruit of poor quality.  So if the fruit are white, this strengthens this hypothesis.

It would help to find out the variety and rootstock of the trees you planted.