Hello Cathie,

Thank you for reaching out to the UVM Extension master gardener program with your question!

That is terrific that your peach tree has lots of fruit. Overall peach tree pruning will depend on age of the tree and type (standard or pillar/upright).

For your specific question, I’ve included a Peach Tree Pruning – Managing Light and Crop Load article from Penn State Extension. There are two paragraphs within this article you may find helpful – The Role of Light and Pruning to Manage Crop Load. This article says, “For fruiting age trees removing upright and vigorous shoots in June and July will reduce shading to maintain fruiting wood in the canopy interior.” It goes on to say, “Summer pruning to reduce shade two to four weeks before harvest will moderately increase fruit red color, but fruit size and sugar levels will be unaffected.” Further that fruit size is negatively related to the number of fruit on a tree. 

If your tree is mature and has been pruned in its early years you should only need to prune in July to totally remove vigorous upright shoots that shade the lower parts of the tree. The article provides more information on pruning guidance for peach trees based on age and type, in case you find it helpful.

I’ve included another article from University of Missouri Extension that discusses peach tree fruit thinning and pruning based on the age of the tree https://extension.missouri.edu/publications/g6030.

Best,