194 MANUAL OF FRUIT DISEASES 
it is an accompanying characteristic of cranberry-rot (see 
page 201). 
When the flowers are affected, they suddenly shrivel and die. 
This effect is commonly known as blast. 
Leaves are not usually affected, but do not always escape. 
Brown spots, irregular in outline, are produced at times. Within 
such areas the black fruiting bodies of the pathogene may be 
found. Ultimately the leaves turn yellow and fall. 
Cause. 
Cranberry-scald is caused by the fungus Guignardia Vac- 
cinit. It was formerly held that it is caused by too much acid 
in the soil. It was also believed that excessive heat and drought 
are contributing factors which induced fermentation in the 
fruit. A condition similar to scald is sometimes induced when 
berries are flooded and kept covered with water for a half day 
or more during hot weather. 
The causal fungus, Guignardia Vaccinit, is found generally 
in the cranberry sections of the country. It was once thought 
that it lived perennially in the stems, and that it entered the 
fruit therefrom. But now this is regarded as a false idea. 
The fungus winters in the old fallen leaves. In the spring 
pycnospores initiate the first infections. The time and manner 
of this process is unknown. But it seems very likely that 
it occurs very early in the growing-season, soon after the water 
is removed from the bog, and while the berries and leaves are 
quite young. Assuming that pycnospores from old leaves 
come to lie on the susceptible parts, then, under conditions 
favorable to the process of germination, a germtube is developed 
from each spore. The organ inoculated is penetrated and a 
mycelium is developed. It appears that after the fungus has 
entered its host it may remain inactive for some time, during 
which period there is no external evidence of the disease or 
the fungus. Thus affected berries may pass unnoticed as 
healthy fruit. The conditions affecting the length of this 
