278 



MANUAL OF TREE DISEASES 



when the covering is broken, a rounded mass of yellow 

 spores (urediniospores) is exposed (Fig. 54). Later in the 





Fig. 54. — Cronartium ribicola (uiedinial stage) on under side of currant leaf. 



season, from the same lesions several slender brown bristle- 

 like structm-es are pushed out from the imder sides of the 



leaves (Fig. 55) . When 

 the affected areas of 

 the leaf are numerous, 

 these brown bristles so 

 completely cover the 

 under side of the leaf 

 that it appears as 

 coarse brown felt, and 

 thus the common name 

 for this disease on cur- 

 rants and gooseberries 

 is felt-rust. But little 

 damage is caused to 

 the affected bushes, al- 

 though defoliation may 

 occur earlier than nor- 

 mally when the leaves 

 are heavily infested. 

 The species of currant 

 and gooseberry vary 



Fig. 55. — Cronartium ribicola (telial stage) on 

 under side of currant leaf. Felt-rust. 



