NOTES ON SOME WESTERN UREDINEAE 

 WHICH ATTACK FOREST TREES^ 



George Grant Hedgcock 



The following paper is summarized from field notes on a num- 

 ber of heteroecious rusts on forest trees in the western United 

 States. 



I. Peridermium filamentosum Peck 



This fungus is the cause of a very serious disease of the west- 

 ern yellow pine (Pinus ponder osa Laws.) in portions of Colo- 

 rado, and probably in adjacent sections of New Mexico and 

 Arizona. This fungus was first discovered by Pringle- in the 

 Santa Rita Mountains in Arizona, July 13, 1881. Although very 

 abundant in certain localities in Montezuma and San Juan 

 National Forests in southern Colorado, it was first discovered in 

 Montezuma National Forest by F. B. Notestein (F. P. 190) the 

 latter part of June, 1910. This collection was the second recorded, 

 a portion of which was sent to Dr. J. C. Arthur and identified by 

 him. Mr. Notestein again collected it on June 26, 191 1 (F. P. 

 1888). Since then the fungus was collected by the writer July 8, 

 191 1, on Pikes Peak, Colorado, in Pike National Forest, in East 

 San Juan National Forest, July 13, 191 1, near Pagosa Springs, 

 Colorado, and in the Montezuma National Forest July 19, 191 1, 

 near Nancos, Ariz., (F. P. 9085). Mr. Notestein reports it as 

 occurring abundantly in various parts of Montezuma National 

 Forest. A tree apparently diseased with the fungus was noted 

 enroute near Telluride, Colorado, July 19, 191 1. 



This species of Peridermium attacks the twigs, limbs, and 

 trunks of both young and old trees in the cambium, but producing 

 little or no swelling of the parts affected. There is a tendency 

 occasionally towards witches broom formation where side limbs 



^ Published by permission of the Secretary of Agriculture. 

 ^Arthur, J. C., and Kern, T". D. North American species of Peridermium. 

 Bull. Torrey Club 33: 418. 1906. 



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