The fruit rot phase is called black rot and on the leaf it is called frogeye leaf spot. The disease can result in losses from a rotting of fruit before harvest and in storage. The premature dropping of infected leaves can result in small, poor-quality fruit and reduces crop yield the following year.
All apple varieties appear to be equally susceptible to fruit rot.
Jonathan and Winesap appear to have the greatest susceptibility to leaf infection. The disease usually starts at the calyx end of the fruit. The fungus usually enters the fruit through wounds caused by insects, hail, growth cracks, or an open calyx tube. At first, a light brown spot forms on the fruit. Usually only one spot occurs per fruit.