A DISEASE OF PINES CAUSED BY CEONARTIUM PYEIFORME. 



taken from specimens of the fungus on leaves of Comandra umbel- 

 late, obtained by inoculations with seciospores from Pinus pungens 

 from Greenwood Furnace, Pa. 



INOCULATION EXPERIMENTS WITH THE FUNGUS. 



Table I gives complete inoculation data for this fungus on Comandra 

 umbellata. Successful inoculations were made with seciospores from 

 two hosts, Pinus ponderosa and Pinus pungens, collected from three 

 widely separated localities in the States of Washington, California, 

 and Pennsylvania. In each instance control plants of the same 

 species were used, and all remained free from infection. Unsuccessful 

 inoculations were made with asciospores from Pinus contorta (Peri- 

 dermium ~befheli) both during 1913 and 1914. In 1914 the failure to 

 infect might have been due to the extreme high temperature of the 

 greenhouse at the time the inoculation experiments were performed. 

 However, the failure for two successive seasons to infect Comandra 

 with the seciospores from Pinus contorta may indicate that the rust 

 on this host is a different species from Peridermium pyriforme, since 

 the shape and size of the seciospores (P. betheli', PI. I, fig. 3) from 

 Pinus contorta are different from those of the type specimen of this 

 rust (PI. I, fig. 1). The writers, in the absence of proof from inocula- 

 tions, assume for the present that these morphological differences may 

 be due to the host and therefore are not of sufficient importance to 

 warrant classifying Peridermium betheli as distinct from P. pyriforme. 



TABLE I. Results of inoculations with the seciospores of Cronartium pyriforme. 



1 Type of Peridermium bethcli. 



1 Sparse here means less than six sori. 



3 Telia immature. 



4 Inoculation made in very hot weather. 



