22 BULLETIN 1046, U. S. DEPARTMENT OF AGRICULTURE. 
All the varieties of winter wheat used can be placed in one of two 
classes: (1) Those which fail to show visible signs of uredinia and 
(2) those entirely susceptible. Those of the first group are desig- 
nated by the symbol R, and those of the second group by S. Among 
the spring varieties there were different types of infection, these 
being represented by the symbols R, to R; and by S. Following is a 
description of the types of rust infection designated by the symbols: 
EXPLANATION OF SYMBOLS USED. 
R=Extremely resistant. 
R,=No uredinia produced. Occasionally very small indefinite flecks, dead areas, 
or yellowish blotches occur. Signs of hypersensitiveness may be present. 
R,=Very rarely the occurrence of minute uredinia (0.1 to 0.5 mm.); presence of 
flecks, dead areas, or blotches.- 
R,=Numerous minute to small uredinia (0.2 to 0.75 mm.); presence or absence of 
yellowish ‘‘islands” surrounding uredinia, or the occurrence of numerous yellow 
blotched areas surrounding or adjoining uredinia. 
R,=Uredinia numerous, variable in size and number (0.2 to 0.4 mm.); flecked or 
blotched, yellow areas present; yellow areas adjoining uredinia. 
R;=Uredinia apparently quite normal in size and shape, but presence of yellowish 
green areas surrounding or adjoining some uredinia indicative of slight resistance. 
S=Showing ordinary susceptibility; uredinia large, normal, vigorous. 
The inoculations of Kanred, P1066, and P1068 both in the seed- 
ling and in the heading stage produced consistent results, indicating 
extreme resistance. 
The hard and soft wheat varieties did not differ strikingly in 
susceptibility, except in the case of Kanred, P1066, and P1068. 
The other hard red winter wheats apparently were as susceptible as 
the soft red winter wheats, although Leach (24) found a “decided 
correlation between the hardness and softness of wheat varieties 
and their relative susceptibility to Puccinia graminis tritici-compacti.”’ 
A greater variation occurred among the varieties of durum spring 
wheat. Beloturka (C. I. No. 1513) seemed to behave very much 
like the three resistant winter-wheat varieties, in that no uredinia 
were formed. In more recent work, however, in which the same 
strain of rust was used, Beloturka (C. I. No. 1513) occasionally has 
shown a few very small uredinia. Some of the durum varieties 
showed more or less uniformly the same type of infection (R, or R,) 
as In the case of Kubanka (C. I. No. 2094), Arnautka (C. I. No. 1493), 
D-5 (C. I. No. 3322), and Gharnovka (C. I. No. 1443). A Poulard 
wheat (C. I. No. 4384) manifested a high degree of resistance. 
Among the emmers there was more or less similarity in the type of 
infection. The type of infectiom fluctuated in both of these groups, 
showing that various factors ae affect the infection results. Two 
White Spring emmers (C. I. Nos. 1524 and 4781) showed the R, and _ 
R, types of infection, while anothe: White Spring emmer (C. I. No. 
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