It looks like you have insect galls on your peach tree. While they may be unsightly, they do not usually cause harm to the health of your tree. You will find them on your tree most years. You can read more about them at the links below. The second is from UC where growing peach trees are more common than in Minnesota. 

If the infestation begins to limit your fruit harvest, you may want to consider intervention early next year.By the time you see the galls, it’s too late to effectively treat for them. 

https://extension.umn.edu/yard-and-garden-insects/insect-and-mite-galls

https://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html