APPLE DISEASES 65 
Symptoms. 
The presence of apple-rust in any locality may be detected 
by examining the apple or the cedar. On the apple leaves 
young spots may be found from April to June. At first these 
are seen on the upper surface as minute pale-yellow areas 
Fic. 17. — Apple-rust; on lower surface (on leaf at extreme left), and on 
upper surface (three leaves on right). 
(Fig. 17, right). These enlarge, become darker, and finally 
are orange-colored. On the upper surface of the spots the 
fruiting bodies of the pathogene develop, first as minute, yellow, 
flask-shaped pustules, which finally turn black (Fig. 17). The 
leaf tissues beneath the spots become swollen and on the lower 
surface another kind of fruiting body is produced (Fig. 17, 
left). This one is cup-shaped and considerably larger than the 
F 
