Leaves on infected shoots turn brown and wither, but remain attached . On the fruit, brown rot infections first appear as soft brown spots . Infections may spread rapidly from fruit to fruit, particularly if environmental conditions are favorable and the fruit are touching one another. All stone fruits become increasingly susceptible to brown rot as they ripen. Both immature and mature fruit infected with brown rot tend to remain on the tree and form mummies.
Mummies remain either hanging in the trees or scattered on the orchard floor during the winter.
Two types of spores are produced from mummified fruit. Ascospores are produced only on mummies that have fallen to the ground and have been partially covered with soil. Ascospores are less common in the Northeast than in semi-arid climates. In the northeast, most brown rot infections develop from conidia that are produced on mummies and infected twigs. Warm, wet weather favors brown rot infection.