50 MANUAL OF FRUIT DISEASES 
the diseased portion is sunken. 
Older spots become lobed, due to the 
secondary extension of the pathogene 
from one or more points in the leaf. 
This activity results in a series of 
more or less concentric areas mak- 
ing up an irregular spot, but in which 
the outline of the original diseased 
portion can still be recognized (Fig. 
12). The center of the lesion be- 
comes grayish brown and the entire 
affected area presents an appear- 
ance which has given rise to the name 
frog-eye (Fig. 12). Frequently the 
small black fruiting bodies of the 
pathogene develop on the leaf-spot, 
although they are not always readily 
noticed on account of their minute- 
ness. The spots are not so conspic- 
uous on the lower surface of the 
leaf. In severe cases the foliage 
turns yellow and may fall six or 
eight weeks prematurely. Bor- 
deaux injury is very similar to this 
leaf-spot. 
The cankers (Fig. 13) are found 
more often on the uppermost side of 
the larger limbs. At first the bark 
is discolored and sunken. The dis- 
coloration is for a short time red- 
dish brown but very soon is darker, the diseased portion, upon 
close examination, being easily distinguished from the surround- 
ing healthy bark. Sometimes the cankers remain small and the 
pathogene dies at the end of the year. In other lesions the 
Fie. 13. — Black-rot canker. 
