344 MANUAL OF FRUIT DISEASES 



and are considerably larger and lighter colored than the pycnia. 

 Within the secia are developed seciospores which blow to and 

 infect the red cedar. These spores may carry for a consider- 

 able distance. Cedar-apples are produced on the cedar as a 

 result of seciospore infection. These cedar-apples are merely 

 irregular, globoid galls measuring an inch or less in diameter. 

 Their appearance has given rise to the popular term cedar- 

 apples. The fungus mycelium developed from the seciospores 

 grows within the tissues of the red cedar, stimulating them to 

 over-growth, whence the gall. From the surface of the gall 

 arise numerous short, beak-like horns which are composed of 

 another kind of rust spores the teliospores. In this rust 

 fungus these spores may be produced year after year for several 

 seasons from the same gall. When moist the beak-like horns 

 become gelatinous and assume a bright orange color. In this 

 gelatinous mass the teliospores grow out and produce a number 

 of smaller spores called sporidia. This takes place in the 

 spring. These sporidia are blown to the pear, apple or other 

 host, where infection results. 



Control. 



Spraying for pear-rust is of little or doubtful value. Since 

 the red cedar harbors the fungus, and since the fungus requires 

 the presence of this plant in order to perpetuate itself, it is 

 logical to destroy all red cedars within a reasonable distance. 

 In the case of apple-rust the distance is put at one mile (see 

 page 70), within which radius all cedar trees should be eradi- 

 cated. 



REFERENCES 



Pammel, L. H. The cedar apple fungi and apple rust in Iowa. Gym- 



nosporangium globosum. Iowa Agr. Exp. Sta. Bui. 84 : 10-16. 



1905. 

 Thaxter, R. Miscellaneous notes. Rust of pears. Connecticut 



Agr. Exp. Sta. Rept. 1890 : 98. 1891. 

 Stewart, F. C. Notes on New York plant diseases, I. Pear. Rust, 



Gymnosporangium globosum Farl. New York (Geneva) Agr. 



Exp. Sta. Bui. 328 : 376-377. 1910. 



