16 INVESTIGATIONS OF BUSTS.. 



Table I. — Culture experiments with black stem rust q/Agropyron andElymus — Continued. 



Date. 



Locality. 



Origin of inoculating 

 material. 



Plant inoculation. 



Period 

 of incu- 

 bation 

 in days. 



Result. 



Feb. 11, 1898.... 

 Do 



Do 



Do 



Do 



Do 



Do 



Lincoln, Xebr 



do 



Ely inns virginicus 



do 



Elymus virginicus 



Elymus virginicus 

 muiicus. 



Elymus canadensis 



glaucifolius. 

 Agropyron tenerum . . . 

 Agropyron occiden- 



tale. 

 Rye... 



13 

 13 



13 



13 

 13 



13 

 13 



11 

 9 



Success. 

 Do. 



do 



do 



Do 



do 



do 



Do 



do 



do 





...do 



do 



Do 



....do 



do 



Wheat 



Do 



Feb. 21, 1898 



do 



Wheat (originally 

 Elymus canadensis 

 glaucifolius). 



El)/in us canadensis . . . 



Hordeumjubalum 



Wheat ... 





Feb. 25 1898 



do 



Do 



Feb. 28, 1898. 



...do ... 



Elymus canadoisis 



glaucifolius. 



Do. b 











« Pustules differ in color from the original. 



bRust changes in appearance. 



The results of these experiments, considered in connection with those 

 recorded in Bulletin No. 16, Division of Vegetable Physiology and 

 Pathology, U. S. Department of Agriculture, appear to establish two 

 things, viz, (1) that the forms of black stem rust on wheat, barley, 

 Hbrdeum jubatum, Agropyron tenerum, A. richardsoni, Elymus cana- 

 densis, and E. canadensis glaucifolius are identical, with the proba- 

 bility that those on Elymus virginicus, E. virginicus muticus, and 

 Holcus lanatus a should be included; (2) that the black stem rust of 

 Agropyron occidentale b is physiologically distinct from any other/' 



A very interesting phenomenon in these experiments was the change 

 in color and form of sorus of the rust produced by a transference to 

 another host. In some cases after a transfer the rust was scarcely recog- 

 nized. The change of color was sometimes from a bright yellow to a 

 deep brown or orange, or the reverse. The uredo of Agropyron tent- 

 rum, for example, was often very } T ellow on the leaves, but changed to 

 brown when transferred to wheat. On the species of Elymus the rust 

 has a brown, w^ax} T appearance, and the teleutospores long remain cov- 

 ered by the epidermis of the host. 



"On January 5, 1900, quite successful infections on wheat were made with the 

 uredospores of black stem rust of this host. 



& Probably the most correct name of this host, which is known also as Agropyron 

 spicatum and A. ghiucui (See Hitchcock, "Note on Nomenclature," Science, vol. 

 17, pp. 827-828, May 22, _j03.) 



'The form on this host was described as a distinct species, named Puccinm agropyri, 

 by Ellis and Everhart, in Journal of Mycology, Vol. VII, p. 131, March 10, 1892, a 

 fact not noticed by the writer until after most of these experiments were made. 

 This species includes jEcidium clematidis D. C. according to Doctor Dietel, the proof 

 of relationship being the result of culture experiments. (Oesterr. Bot. Zeitschr., 

 No. 8, 1892.) 



