BLACK STKM RTTRT OF WTIKAT. 



53 



The miinber of host phmts has beeu considerably reduced in recent 

 years by the separation of a number of new species, and also by more 

 correct identifications. Some of the new species occurring in this 

 country are P. aniphu/cna Diet., T. subuiteiis Diet., P. <1i,sfichlitJis Ell. 

 and Ever., P. at/ropyri 1011. and Ever., and P. jiihnfa Ell. and T>arth., 

 but whether these are all good species the writer is not yet prepared to 

 say. The last one, however, he believes is not.' 



PhyKiohH/ical relations. — Long before the writer's inoculation experi- 

 ments were begun he often noticed, as doubtless others have also, a 

 considerable difference between the general appearance of the black 

 stem rust of wheat and of oats. In fact tlie uredo stages on the two 

 hosts, at least on the leaves, ai)pear to differ from each other more than 

 the uredo stages of /'. rubigo-vera and /'. coronata. The sori are longer, 

 larger, and seemingly a little darker on oats than on wheat, and 

 usually there is proportionally more of the uredo present on the former 

 than on the latter, though this latter feature is quite variable. Of 

 course such differences maybe due to differences in constitution of the 

 host plants, but this is not necessarily so, for the leaf rust and crown 

 rust on the same hosts behave differently. 



Believing such work would be of particular interest, the writer 

 inaugurated some inoculation experiments with this widely distributed 

 rust species, the experiments with the form on oats being started sooner 

 and carried on to a greater extent than those with the form on wheat, 

 which latter, on account of lack of inoculating material, were not begun 

 until Aj^ril 20, 1896. The sources of inoculating material were Uredo 

 (jramlniH of wheat, kindly sent in by Prof. E. II. Price, April 14, 1896, 

 from the Texas Agricultural College farm, and barberry rust, furnished 

 through the kindness of I*rof. C. F. Wheeler, May 9 and 11, 1890, from 

 the Michigan Agricultural College. These experiments are very incom- 

 plete, but are still under way. The following table gives a summary 

 of the work so far done : 



Tablk 8. — Inoculation experiments with Uredo <iraminiH tritici and ^^cidium herberidis. 



Date of 

 inocula- 

 tion. 



1896. 

 May 1 



Do... 



Do... 



May 9 



bo... 



Do... 

 Do... 

 Do... 

 Do... 

 Do... 

 May 20 



Origin 



Place where experi- of inocu- 

 meuta were made. lating 



material. 



"Washington, D. C "Wheat. 



.do 

 .do 

 .do 

 .do 



.do 

 .do 

 .do 

 .do 

 -do 

 .do 



.do .. 

 .do .. 

 .do -. 

 .do .. 



.do . . 

 .do . 

 .do .. 

 .do .. 

 .do .. 

 .do .. 



Plant inoculated. 



Australian Glory wheat. 



Period | 

 of incu- 

 bation j 

 (days).. 



Shirosawa wheat 



Ligo wo oata 



"Wheat 



BloHuts Lambrigg wheat x Horn- 

 blende. 



Wheat 



Banatka wheat 



Wheat 



Oats 



do 



Wheat 



11 



U 

 11 

 11 

 11 



11 

 11 

 11 

 11 

 11 

 12 



Result. 



Only one or 



two spots. 

 Negative. 



Do. 

 Successful. 

 Only one or 

 two spots. 

 Successful. 



Do. 



Do. 

 Negative. 



Do. 

 Successful. 



' More recent experimeuts made by the writer show conclusively that P. jiibata is 

 not only the same as F, graminis, hut is identical with the form tritici of wheat and 



barley. 



