Identifying the disease:
Yellow spots that later turn brown are found on apple and hawthorn leaves. These spots cause the leaves to curl up and under. On redcedar trees, look for reddish-brown, round galls and, in the spring, the orange, jelly-like horns that develop from the galls.

Susceptible trees:
The primary hosts of cedar-apple rust are trees in the rose family, including apple (Malus spp.), hawthorn (Crataegus spp.), and pear (Malus spp.). The alternate hosts are eastern redcedars (Juniperus virginiana) and southern redcedars (Juniperus silicicola). The disease is most commonly found in areas where apples or hawthorn trees are close to redcedar trees.