APPLE DISEASES 17 
epidermis exposing pink masses at their tips (Fig. 5). As the 
spot increases in diameter the pustules follow rather closely the 
advancing circumference of the lesion. At the same time the 
spot is developing outwardly, it is also progressing inwardly, 
and a section made perpendicular to the surface, through the 
center of the spot, shows the rotted area to be funnel-shaped. 
Finally, the whole 
fruit is involved and 
a mummy is the re- 
sult (Fig. 5). Some 
of the affected fruits 
fall while others cling 
to the tree for at 
least a year. Spots 
which have been re- 
tarded by cool 
weather have an 
especially prominent 
purplish margin. 
Many late infections 
are reddish or pur- 
plish specks, never 
developing further 
on account of ad- 
verse conditions. 
Cankers are devel- 
oped on the twigs, limbs (Fig. 6) and fruit-spurs. Trunks 
rarely show bitter-rot cankers. Smaller twigs are some- 
times wholly and suddenly killed, resulting in a twig-blight. 
The Jonathan and Willow varieties are more subject to this 
type of injury than others. Most cankers on the limbs have 
at their center a dead twig or evidence of one having been 
there (Fig. 6). The canker is at first a small discolored area in 
the outer bark, the smooth edges of which are sharply set off, 
c 
Fic. 6. — Bitter-rot cankers. 
