CHAPTER XV 

 CEDAR DISEASES 



The white cedar of the Atlantic Coast and incense cedar of 

 the Pacific Coast are affected by several destructive diseases. 

 These two trees belong to different genera (Chamsecyparis 

 and Libocedrus). The diseases affecting the white cedar do 

 not occur on the incense cedar and vice versa. They are dis- 

 cussed together in this chapter merely for the convenience of 

 grouping them under the name common to both. 



The two rust diseases (witches'-broom and branch-swellings) 

 on the white cedar cause serious deformation of the trees and 

 even death when they occur. The incense cedar is also af- 

 fected by a rust-fungus which causes witches'-brooms. The in- 

 cense cedar is subject to a destructive heartwood-rot, which 

 is similar in appearance to the pecky heartwood-rot of bald 

 cypress. The brown felt-blight of incense cedar is important 

 at high altitudes. 



Eastern Leaf-Rust 



Caused by Gymnosporangium fraternum Kern 



The white cedar is sometimes affected by this leaf-rust, 

 along the Atlantic Coast from Massachusetts to New Jersey. 

 No damage is done to the trees. The symptoms are confined 

 to the spore-masses of the pathogene which break through the 

 epidermis of the affected leaves. These spore-masses appear 

 in the spring and are small brown cushion-shaped pustules 

 about an eighth of an inch in diameter. The life history of 

 the causal pathogene is completed on the leaves of chokeberry 

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