PINE DISEASES 285 



coming on. However, a few will always escape detection and 

 if the Comandra plants are abundant, several pines may be- 

 come infected during a season when only one existed in the 

 spring. 



RErBRBNCES 



Arthur, J. C, and Kern, F. D. The rediscovery of Peridermium pyri- 

 forme Peck. Science 38 : 311-312. 1913. 



Hedgoock, G. G., and Long, W. H. A disease of pines caused by Cro- 

 nartium pyriforme. U. S. Dept. Agr. Bui. 247 : 1-20, pis. 1-2, 

 fig. 1. 1915. 



Hedgcoek, G. G., and Long, W. H. Two new hosts for Peridermium 

 pyriforme. Jour. Agr. Res. 5 : 289-290, pi. 27. 1915. 



Orton, C. R., and Adams, J. F. Notes on Peridermium from Pennsyl- 

 vania. Phytopathology 4 : 23-26, pi. 3. 1914. 



Castillbja Rust 



Caused by Cronartium coleosporioides (D. and H.) Arthur 



This blister-rust disease occurs from the Rocky Mountains 

 to the Pacific Coast Range and from Canada to Mexico. It 

 is exceedingly destructive to lodge-pole and western yellow 

 pine. Large knots and tankers are formed on lodge-pole pine 

 which at times are similar to the oak rust of pines (see page 287). 

 The trunks of many trees five inches in diameter are girdled 

 by the cankers, which may be from two to eight feet long. The 

 bark soon dies and the death of the tree or branch follows. 

 Fifty per cent of the stand is sometimes seriously affected. 

 This fungus requires, the presence of the weeds, Castilleja 

 miniata and other species of the same genus, in the vicinity 

 of the pine in order to complete its development. When these 

 plants do not exist, this fungus cannot affect the pines. 



Symptoms. 



Both young and old trees are affected. Small trees in the 

 nursery show but little enlargement of the affected branches 

 or trunk. Large orange-colored blisters burst through the 



