216 MANUAL OF FRUIT DISEASES 
cultivated currants and gooseberries; this stage is known as 
Cronartium Ribicola, the name now used to apply to any and 
all stages of the fungus on whatever host it is found. 
The fungus lives from year to year in the bark of living pines 
(Fig. 57), finally fruiting and developing a crop of #ciospores 
Fic. 57. — Euro- 
pean currant-rust; 
cia on white pine. 
which blow to Ribes (currant and goose- 
berries) near by. In pines the organism 
may be shipped thousands of miles. It is 
not known whether the fungus hibernates 
on the Ribes or not, although there is some 
evidence that such is the case. In the 
spring from early April to June (chiefly in 
May), the eciospores are blown to young 
Ribes leaves. These spores are produced 
over a period of about two weeks. They 
apparently are never carried more than a 
few hundred feet. Should any of these 
spores fall on pines, infection will not re- 
sult; the fungus cannot pass from pine to 
pine ; it must first go to the currant or goose- 
berry, if it is to grow. In the presence of 
moisture the eciospores germinate and 
infect the Ribes leaves. Cold weather 
inhibits the rapid progress of the fungus in 
the currant leaves. With a favorable tem- 
perature the fungus soon establishes itself, 
and after two weeks a new crop of spores 
is produced. These are always produced 
on the lower surface of the Ribes leaf. 
They are distinct from the eciospores which 
come from the white pine, and are known as uredospores. The 
uredospores are capable of infecting other currants and goose- 
berries. This stage is sometimes called the summer or repeat- 
ing stage (Fig. 55). This repetition may proceed throughout 
