714 
Journal of Agricultural Research 
Vol. XXVIII, No. 7 
A possible exception to this statement is the reaction to the rust collected at 
Eureka. In general, the reaction to it was the same as to the rusts from other 
sources, but in the numerous lots included under White Tartar (White Russian), 
which is uniformly resistant to all the other rusts used (except for an occasional 
rogue in R 284a and 1102-5), an occasional plant proved susceptible to the Eureka 
rust. One or two plants susceptible to the Eureka rust were found in Green 
Mountain, R llOe; Long’s White Tartar, C 1026; White Tartar (White Russian), 
I 102J-7; and White Tartar (White Russian), C 1016. These occurrences are 
indicated by the footnote c in Table IV. It is possible that these susceptible plants 
also are rogues; but it seems unlikely, because the same lots of seed produced 
plants w T hich reacted uniformly to the rust from other sources. 
It was reported that in Eureka stem rust occurred on Richland, another 
resistant variety. Rust specimens were obtained from Eureka at three different 
times. In each case the material contained a mixture of crown and stem rusts, of 
which only the crown rust grew on the Richland. It may be that a form of 
stem rust occurs there to which Richland is susceptible, but, if so, the writers 
failed to obtain it. Our only indication of a different rust form is the reaction 
to White Tartar (White Russian), and this is inconclusive evidence. 
Stakman and Levine and their associates have described in several of their 
papers (16, 18) & condition in which the infections on a single leaf vary greatly 
in size and vigor. They have named this the heterogeneous or X type of infection 
as noted earlier in this paper. 
The oat stem rust on Joawette (R 125e) showed a similar variability and may 
belong to the X type. Some plants of Joanette appeared to be susceptible, some 
resistant, and some showed two or more distinct reactions on the same leaf. No 
explanation of this condition can be offered at present with any assurance. 
Stakman, Levine and Bailey (17, 18) in their reports on specialization of Pac¬ 
tinia graminis avenae distinguished certainly four, and perhaps five, physiological 
races of stem rust. Victory (C. I. 1145), White Tartar (C. I. 1614), and Monarch 
Selection were used as differential hosts, with results which may be summarized 
roughly as follows: 
Form No. 
Victory j 
White Tartar 
(White Russian) 
Monarch Selection 
I 
Susceptible.. 
Resistant. 
Immune. 
Susceptible. 
Do. 
Do. 
Heterogeneous type. 
II . 
Ill . 
.do... 
Intermediate in 
resistance. 
Susceptible_ 
IV 
_do.. 
V 
1... 
; 
i 
So far as can be judged from the limited data available, all the collections of 
oat stem rust used in the experiments represent the physiological race II, as 
plants of Victory and Monarch Selection were susceptible and White Tartar was 
highty resistant. 
