a 
APPLE DISEASES 7 
older the delicate fungal coating becomes extinct at the center, 
and exposed at this point is the brown corky layer of the host- 
tissue. This frequently becomes checked and cracked. In 
some cases the whole spot thus becomes corky so that the 
pathogene disappears entirely, leaving a russeted scar on the 
side of the fruit. Scab spots often cause a dwarfing of the 
side of the apple on which they occur. When the attack is 
severe, the fruit shrivels and falls. The removal of the cuticle 
permits the entrance of 
rot-producing pathogenes, 
and consequently decay 
of the apple-flesh appears 
beneath scab spots. Late  . +: 
infections, which appear = #** 
at picking time, are much 
smaller, being scarcely 
more than mere specks;  ~ # 
they are also very black 
and no marked depres- 
sion nor dwarfing of the 
fruit accompanies such in- ea ee 
fections. The scab spots : es 
on twigs vary with the Fic. 2. — Apple-scab, margins of spots 
variety affected. In some showing uplifted cuticle. Lesions about 
: . blossom-end. 
cases the affected portion 
becomes somewhat swollen, and the twig as a whole becomes 
prominently blistered. Severely attacked young twigs may ap- 
pear blistered over the surface to such an extent that the bark 
will subsequently peel in flakes. This type of injury is common 
in Europe, and is called grind or scurf by the Germans. In 
other cases the shoots are not swollen and do not present a 
blistered appearance. A third type of symptom on the twigs 
is found in cases where the scab spots are isolated, pock-like 
markings. 
