84 INSECT AND FUNGOUS ENEMIES OF THE APPLE. 
ing summer, enlarging the gall, and finally during the second spring 
throws out long, yellowish, gelatinous projections in which spores are 
borne. These spores, while still in the gelatinous mass, germinate, 
producing a short fungus growth which bears a crop of smaller 
secondary spores. When the yellowish mass dries these secondary 
spores are carried like dust particles on the wind and when lodged 
on the fruit or foliage of the apple germinate, giving rise to a 
fungous thread, which enters the tissues and finally produces the 
characteristic yellow or orange-colored spots. Later the cluster cups 
are formed on the underside of the leaf and on the fruit spots. In 
these cups are produced another kind of spore, which is carried back 
to the cedar trees, as previously indicated. This takes place during 
July, August, and September. The spores produced on the apple 
can not reinfect this plant, but 
must find their way to the cedar 
or perish. Spores for the in- 
fection of the apple must come 
from the cedar. 
INFECTION PERIOD. 
Plenty of moisture is re- 
quired, both for the production 
of spores on the cedar apples 
these spores on the leaves and 
fruit of the apple. It natu- 
rally follows, then, that a seri- 
ous outbreak of the disease is 
Fic. 19.—Cedar rust disease on the cedar. likely to occur during a wet 
pode es a spring, while if dry weather 
prevails very few, if any, infections can take place. Beginning about 
the time apple trees are in bloom, infections may take place over a 
period of three to six weeks, depending upon weather conditions. 
In warm, wet weather during this period the cedar apples throw 
out the yellow gelatinous masses in which the spores are produced. 
These may dry out and swell up again several times with alternate 
dry and wet weather, more spores being liberated each time. Such 
weather conditions prolong the infection period and result in a 
serious outbreak of the disease on the apple. 
TREATMENT. 
Since the fungus causing the disease comes from the cedar trees 
and since the apple can not become infected from any other source, 
the natural and most effective remedy is to destroy all red cedars in 
orchard districts. The cedars in fields or woods adjacent to the 
492 
and for the germination of 
sium offs 
