CEDAR DISEASES 135 



swellings. These pustules become gelatinous and sometimes 

 may become confluent. 



Cause. 



The branch-swellings of white cedar are caused by the rust- 

 fungus, Gymnosporangium boiryapites. The teliospores pro- 

 duced on the brown pustules on the cedar bark germinate and 

 form basidiospores which are innocuous to the cedar and can 

 infect only the leaves of the common service-berry. Here, 

 after a few weeks' growth, seciospores are formed which, if 

 they find their way to the white cedar, cause, the infection of 

 the branches and the swellings result after a year or two. For 

 further details concerning the life history of this type of rust, 

 see page 192. 



Control. 



Since the fungus can only exist in a region where the white 

 cedar and service-berry stand within a relatively short distance 

 of each other, the eradication of the service-berry serves as a 

 simple method of control. A separation of these two kinds of 

 trees by a few hundred feet may prove effective, although for 

 similar rusts of the juniper, a mile has been found to be a more 

 desirable distance. 



Reference 



Harshberger, J. W. Two fungous diseases of the white cedar. Proc. 

 Acad. Nat. Sci. Phila. 1902 : 461-504. 1902. 



Pecky Heartwood-Rot 



Caused by Polyporus amarus Hedgcock 



The heartwood-rot of incense cedar, known as pin-rot, pecki- 

 ness, dry-rot or pin-disease, does great damage to this tree in 

 California and Oregon. All of the trees in a given area are 

 sometimes found to be affected, the middle portion of the 



