|Peaches after thinning. 4.9.15 El Dorado genetic dwarf.|
The genetic dwarf peaches have very short internodes, so can be left closer together compared to normal-length internode peaches. It's not the distance, so much as how many leaves are needed to support each leaf.
This article states that 30 to 45 leaves are needed per peach for the best production. That is not on genetic dwarf peaches, which tend to have smaller fruit. I don't know when it needs to be 30 to 45 leaves - early or near harvest. I need to find some more articles - that # of leaves seems like much more than I recall.