What causes sap and fruit drop?
Certified GKH Gardening Expert
This can be anything from pests to fungal infections. Treat every spring with wettable sulfur or a copper fungicide. Once it is in the tree, you will just have to treat for symptoms at the start of each year. This is usually incurable. This article will help: https://www.gardeningknowhow.com/edible/fruits/peach/common-peach-diseases.htm