A DISEASE OF PINES CAUSED BY CRONAETITJM PYEIFOEME. 



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

 lata obtained by inoculations with aeciospores 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 aeciospores 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 aeciospores from Pinus contorta (Peri- 

 dermium betheli) 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 aeciospores 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 aeciospores (P. betheli; PL 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 ivith the xciospores of Cronartium pyriforme. 



iEcial host, serial num- 

 ber, and locality. 



Species inoculated. 



Date of 

 inocula- 

 tion. 



Results. 





Ure- 

 dinia. 



Telia. 



Degree of 

 infection. 



Collector. 



Pinus contorta: 



8500, Eldorado 



Comandra umbellata. . 

 Comptonia asplenifolia 

 Comandra umbellata. . 



1913 

 June 18 



...do.... 







No infection. . . 

 do 



Bethel. 



Springs, Colo. 

 8500, 1 Eldorado 







Do. 



Springs, Colo. 

 8514, Allenspark, 

 Colo. 

 Do 



June 27 

 ...do 







do 



Do. 







do 



Do. 



Pinus ponderosa: 

 12467, Wenatchee, 

 Wash. 

 Do 



Comandra umbellata. . 

 ...do 



1914 



May 27 



May 30 

 May 28 



May 29 

 May 30 

 ...do 



1914 

 June 5 



June 9 

 June 6 



June 7 



June 10 



June 11 

 ...do.. 



June 12 

 June 13 

 ...do.. 



1914 

 June 28 



Julv 4 

 July 5 



June 30 

 July 15 

 . do.. 



Sparse 2 



do 



do 



Very abun- 

 dant. 

 do 



do 



Fisher. 

 Do. 



12468, Roeky 

 Gulch, Cal. 

 Pinus pungens: 



do 



Boyce. 



Hedgcock. 

 Do. 



do 



Furnace, Pa. 



do 



Furnace, Pa. 

 Do 



do 



Do. 



15462, Greenwood 



do 



June 1 



June 2 

 ...do 



July 1 



July 4 

 July 8 

 July 5 



Sparse 



Abundant 3 . . . 



do 



Sparse 



No infection 4 . . 



do 



Do. 



Furnace, Pa. 

 Do 



do 



Do. 



Do 



do 



Do. 



Do 



do 



June 3 

 July 3 

 ...do 



Do. 



Pinus contorta: 



15550, E 1 d o r a , 



do 



Do. 



Colo. 



Do 









Do. 















1 Type of Peridermium betheli. 



2 Sparse here means less than six sori. 



3 Telia immature. 



4 Inoculation made in very hot weather. 



