Brown rot is destructive to peaches and all stone fruits. Fungi overwinter in twigs or in infected fruit, either on the tree or on the ground. Healthy flower buds are infected by blown or splashed spores. Spores from infected blossoms are blown to healthy fruit. The more mature the fruit, the more susceptible it is to infection.
Spray a sulfur-based fungicide over the entire tree at "pink" flower and bloom stages. We recommend Sulfur Guard™ Fungicide.