134 MANUAL OF TREE DISEASES 



apple host cause infection of the leaves. The seciospores formed 

 sometime later infect the cedar leaves in the summer and au- 

 tumn. The fungus over-winters as mycelium in the cedar 

 leaves. Further details concerning the life history of rusts of 

 this type will be found under jumper diseases, on page 192. 



References 



Jackson, H. S. A Paeifle Coast rust attacking pear, quince, etc. 



Second Biennial Crop Pest and Horticultural Report (Oregon 



Agr. Exp. Sta.) 1913-1914 : 204^212. 1915. 

 Jackson, H. S. A new pomaceous rust of economic importance, 



Gymnosporangium Blasdaleanum. Phytopathology 4 : 261-269, 



pis. 12-13. 1914. 



Branch-Swelling 

 Caused by Gymnosporangium botryapite$ (Schw.) Kem 



The white cedar on the Atlantic Coast from Massachusetts 

 to New Jersey and Pennsylvania and in southern Alabama 

 is often affected by this disease. The branch-swelling and 

 witches'-broom diseases of white cedar are the most serious 

 to this tree. Because, however, of the peculiar life history 

 of the rust-fungi which cause them, they are not generally 

 prevalent. The spores formed on the cedar branch-swellings 

 cause the infection of the leaves of the service-berry and an- 

 other type of spores formed on these leaves in turn causes 

 infection of the branches of the white cedar. Thus it is seen 

 that this fungus cannot exist unless the service-berry is in close 

 proximity to the cedars. 



Symptoms. 



The infected branches become swollen to two or three times 

 the normal size. The swellings are spindle-shaped and may be 

 several inches long. In the spring, brown pustules about an 

 eighth by a quarter of an inch burst through the bark of the 



