158 MANUAL OF TREE DISEASES 



epidermal cells of the stems and over-winter there. The 

 germ-tubes bearing basidiospores are pushed out the fol- 

 lowing spring and infection of the fir needles is accomplished 

 when the basidiospores are blown to them. The white blisters 

 appear on the needles in late spring. The affected needles 

 may appear yellowish and usually drop off in late summer. The 

 blister-stage on the fir is known as Peridermium columnare 

 Schmidt and Kuntze. This fungus is common throughout the 

 United States on blueberry but is rarely found on firs. 



TJncdnnected rusts. 



Two blister-rust fungi attacking fir needles (Abies) in north- 

 western United States have been named provisionally Peri- 

 dermium omamentale Arthur and P. Holwayi Sydow. These 

 two forms may represent only a single species, however, as 

 they are very similar microscopically. The alternate stages 

 of these rusts are as yet unknown. 



References 



Weir, J. R., and Hubert, E. E. Observations on forest tree rusts. 

 Amer. Jowc. Bot. 4 : 327-335, figs. 1-2. 1917. 



Clinton, G. P. HetercBcious rusts of Connecticut having a perider- 

 mium for their SBcial stage. Connecticut Agr. Exp. Sta. Ann. 

 Rept. 1907-1908 : 369-396, pis. 25-32. 1908. 



Arthur, J. C, and Kern, P. D. North American species of Perider- 

 mium. Bui. Torrey Bot. Club 33 : 403-438. 1906. 



Eraser, W. P. Cultures of some heteroecious rusts. Mycologia 3: 

 67-74. 1911. 



Eraser, W. P. Cultures of heteroecious rusts. Mycologia 4 : 175- 

 193. 1912. 



Eraser, W. P. Further cultures of heteroecious rusts. Mycologia 6 : 

 233-239. 1913. 



Eraser, W. P. Notes on Uredinopsis mirabilis and other rusts. My- 

 cologia 6:25-28. 1914. 



Hedgcock, G. G. Notes on some western Uredinese which attack 

 forest trees. Mycologia 4 : 141-147. 1912. 



