I was wondering if you have any suggestions for naturally addressing leaf curl on peach trees in our climate?
If you don’t want to use sprays, the advice from the Ontario Ministry of Agriculture and Rural Affairs (OMAFRA) is to control by pruning out infected branches: https://www.omafra.gov.on.ca/english/crops/gardbk/gh-ch5-4tdr.htm#7
Lime sulfur, which is permitted by the Ontario Pesticides Ban, can also be used as a dormant spray to control peach leaf curl, applied in early spring before bud break.
Unfortunately, no other natural controls are available for an existing tree. Choosing resistant cultivars is recommended. Also, as the spores are washed into the buds by spring rains, one recommendation is to espalier the tree in a sheltered spot, such as beneath a roof overhang. Neither of these might be possible for you, but file the info away for future reference.
Good luck with your peaches.