Q.Is It Too Late To Treat A Peach Tree That Has The Curling Orange Leaves And Bearing Fruit Already
My peach tree is fairly young 3-4 yrs old and last year developed the fungus on the leaves, There were a lot of peaches but all had the disease and almost all fell off, whatever was left was not salvageable.I did not treat the tree and this year again after the bloom and the leaves grew the fungus is back. I shall treat it this fall and next spring but is it worth it to spray anything this yr. I have a dog so have to be careful and he picks the fallen fruit.

Certified GKH Gardening Expert
This is going to be a lifelong issue. You will need to treat every year at the appropriate time, or it will return.
Here is an article that will help:
https://www.gardeningknowhow.com/edible/fruits/peach/peach-leaf-curl.htm