VARIETAL SUSCEPTIBILITY OF OATS TO SMUTS 3 
Tubeuf (19) inoculated 25 varieties of oats with the spores of 
TJstilago avcnae and found great differences in the percentages of 
smut which developed. With one exception (Avena sativa var. aris- 
tata) all the varieties were infected. In a second experiment he grew 
six varieties, and all of them proved to be more or less susceptible. 
In this experiment A. sativa aristata was severely attacked. The 
Hopetown variety gave the highest percentage of infection in both 
experiments. 
Rose (14) carried out an experiment with carefully inoculated seed, 
in which he used 63 varieties and sowed two lots of seed of each, one 
early in the season and the other late. Wide differences were noted 
in the percentage of smut in the different varieties. They showed 
infection varying from 1.76 to 17.67 per cent. Two varieties, 
Schwarzer Brie and Oderbrucher, gave negative results. In general, 
a higher percentage of infection was obtained in the later seeding. 
Appel and Gassner (1) mention the fact that Fiehtelgebirgs and 
other mountain varieties of oats are much more susceptible to smut 
than Ligowa, Hiltner (?) also refers to the great susceptibility of 
Fiehtelgebirgs oats as compared with Ligowa. 
Mc Alpine (11) successfully infected both wild and cultivated oats 
with spores of TJstilago avcnae from wild oats. He also infected wild 
oats with spores from cultivated oats. 
In a previous publication the senior writer (13) has described his 
experiments on the resistance and susceptibility of species and varie- 
ties of Avena to both the loose and the covered smut. The experi- 
ments with TJstilago avenae extended over a period of five seasons, 
during which 154 agronomic varieties and strains belonging to seven 
species of Avena were grown. These agronomic strains and varieties 
were distributed as follows: Avena brevis Roth, 3; A. fatua L., 3; A. 
nuda L., 4; A. sativa L., 99; A. sativa orientalw L., 24; A. sterilis L., 
18; and A. strigosa Schreb., 3. The experiments with TJstilago levis 
were continued during four seasons, and 146 agronomic strains and 
varieties belonging to the same seven species of Avena were grown. 
The strains and varieties were the same with the exception that six 
strains of A. sativa and two of A. sativa orientalis were omitted. 
It was found that all the strains of the species Avena brevis Roth 
and A. strigosa Schreb. were entirely free from infection. In the 
experiments with TJstilago avenae 995 plants of A. brevis and 1,247 
plants of A. strigosa were grown. In the experiments with TJ. levis 
996 plants of A. brevis and 1,010 of A. strigosa were grown. 
Avena fatua L. proved quite susceptible to both smuts. The 
infection with TJstilago avenae varied from 26.9 to 38 per cent and 
with TJ. levis from 17.4 to 60.7 per cent. 
All the strains of A vena nuda L. proved extremely susceptible. The 
percentages of infection obtained usually were very high and in 
general averaged above 50 per cent. 
All the varieties and strains of Avena sativa orientalis L. were 
moderately susceptible. Infection rarely exceeded 50 per cent, but 
the average for all the different varieties was above 25 per cent. 
The large number of strains and varieties of Avena sativa L. showed 
a considerable range in the degree of susceptibility to both smuts. 
A few varieties, of winch Canadian, Early Champion, and Victor 
are the best illustrations, proved very susceptible, but most varieties 
showed only moderate percentages of infection. A few, for example,, 
