BLACK STEM RUST OF AGROPYRON AND ELYMUS. 



15 



Black Stem Rust of Agropyron and Elymus. 



At least three and probably four different rusts occur on the species 

 of these two grass genera, and are often so closely associated that 

 their accurate identification is extremely difficult. Of the herbarium 

 specimens of these rusts throughout the country, probably not one in 

 Miy is identified with any certainty. The writer's experiments with 

 these forms are still incomplete, but a few things at least have been 

 established. When these grasses are brought under cultivation the 

 changed conditions and proximity to other grasses and grains cause 

 them to become much more rusted than is ordinarily the case. In 

 the cultivated grass plats at the experiment stations in Oklahoma, 

 Kansas, and Nebraska the rusts were found in great abundance. It 

 was therefore easy to carry on many culture experiments. These 

 experiments with the uredospores of black stem rust were sufficiently 

 numerous to make it desirable to arrange them in the following table: 



Table I. — Culture experiments with black stem rust of Agropyron and Elymus. 



Date. 



Locality. 



Origin of inoculating 

 material. 



Plant inoculated. 



Period 

 of incu- 

 bation 

 in days. 



Result. 



Jan. 9, 1897 



Washington, D. C. 

 do 



Wheat 



Elymus virginicus 



Wheat . 



10 

 10 

 11 

 11 



11 

 11 

 6 

 6 



12 

 8 



8 

 8 

 16 

 16 

 16 

 16 

 18 

 18 

 18 

 18 

 15 

 21 



21 



10 



10 

 11 



14 

 14 

 14 

 14 



14 



14 



14 

 14 

 14 





Do 



do 



Do 



Jan. '22, 1897.... 



do 



do 



Elymus virginicus 



Agropyron richard- 



soni. 

 Wheat 



Do. 



Do 



do ... 



...do... 



Do 



Do 



do 



do 



Do 



Do 



do 



...do ... 



Agropyron occidentale 

 Wheat 





Sept. 13, 1897 . . . 



Stillwater, Okla . . . 

 do 



Agropyron tenerum. . . 





Do 



Agropyron tenerum .. 

 Wheat 



Do 



Oct. 5, 1897 



Manhattan, Kans . 

 do 



Agropyron occidentale 

 Wheat (originally 

 Agropyron tenerum) . 

 do 





Do 



do . 





Do 



do 





^■i 



Do 



do 



...do... 



Agropyron tenerum . . 



Oct. 21, 1897 .... 



do 



...do ... 





Do 



do 



do 





Do 



Do 



....do 



...do.. 



Oats 



(*). 



Do 



do 



...do ... 



Rye 



Do 



do... 



Agropyron occidentale 



Wheat 



Rye 



Do 



Do 



do 



Do 



Do 



do 



do 





Do 



Do 



do.... 



. do . 



Agropyron tenerum . . 

 Agropyron occidentale 

 Wheat. 



Do 



Nov. 24, 1897 ... 





...do ... 





Jan. 5, 1898 



do 



Elymus canadensis 



glaucifolius. 

 do 



Do e 



Do 



do 





Do 



Jan. 21, 1898 



do 



Wheat (originally 

 Elymus canadensis 

 glaucifolius). 

 do 



Wheat . . . 



Do 



Do 



do 





Do 



Feb. 11, 1898.... 



do 



Elymus canadensis 

 glaucifolius. 

 do .. 



Wheat 



Do./ 

 Do 



Do 



do 





Do 



do 



do.... 



Rye 





Do 



do 



do . 



Oats 



Do 



Do 



do 



do 



Elymus canadensis 

 glaucifolius. 



Elymus virginicus 



Elymus virginicus 

 muticus. 



Elymus intermedins. . 



Agropyron tenerum . . 



Agropyron occiden- 

 tale. 





Do 



do 



.. do 



Failure. 

 Do 



Do 



do 



...do 



Do 



do 



do 



Do. 



Do 



do 



do 



Do 



do 



...do 



Do 











a Pustules differ in color from the original. 



bl pustule only. 



c Conditions very unfavorable, however. 



d Apparently 1 pustule formed. 



e Rust changes color and form of pustule. 



/Rust changes color. 



