= 
70 
new oat hybrids for testing. Of 3&8 selections of Victoria « 
Fulgrain, 11 were resistant anc 
| REN 
27 susceptible. 
Studies on the Inheritance of Smut Resistance 
The second generation plants of oat hybrids involving Victoria 
and Monarch were grown. These were inoculated with Race | 
of the covered smut, to which Victoria is resistant, while Monarch 
is susceptible. The data secured indicate a single genetic factor 
for resistance. 
The second generation plants of a hybrid between Markton and 
Navarro, both highly resistant varieties, were tested; 86 plants 
inoculated with Race 1 of the loose smut and 84 inoculated with 
Race 1 of the covered smut gave no infection. The second gen- 
ration plants of a third hybrid between Markton and Red Rust- 
proof were inoculated with the Red Rustproof race, and out. of 
136 p 
The third generation of these hybrids will be grown in 1943 and 
doubtless will throw additional light on the factors for resistance 
involved. 
— 
ants grown 13 were infected (9.5 per cent). 
The first generation plants of 33 new oat crosses were grown. 
— 
—_— 
These crosses involve various combinations of resistance in rela- 
tion to the different races of both loose and covered smuts. The 
data for the second generation plants of many of these will be 
obtained this coming year. 
A number of new crosses were made by Miss Jeanne P, Walther. 
These are designed to throw further light on the mode of inheri- 
tance of resistance to both loose and covered smuts. 
Studies on Experimentally Produced Physiologic 
Races of the Oat Sinuts 
Dr. L. Gordon Utter, research assistant, carried out further 
experiments on the reaction of 34 — of smut resulting 
from the hybridization of Races | of loose and covered smuts. 
In these experiments 9 distinct races of loose smut and 13 « 
covered smut were differentiated on iz oat varieties from 1938 to 
1941. The 1942 data indicate that 5 of the remaining collections 
of covered smut could be pene from the other races by the 
