51 
REPORTS ON RESEARCH FOR 1939 
PLANT PATHOLOGY 
By Georce M. REEpD 
Studies on the Inheritance of Resistance of Oat Hybrids to Loose 
and Covered Smuts 
Studies on the inheritance of smut resistance of oat hybrids 
were continued, many third generation progenies of different 
crosses being grown. Duplicate sets of seed for growing 145 
third generation progenies of Green Mountain X Monarch were 
inoculated, one with Race 1 of the loose smut and the other with 
Race 3 of the covered smut, the latter originally obtained from 
France. The data indicate that inheritance of resistance to both 
of these smuts depends upon a single factor difference and, further, 
resistance to each smut is inherited independently. The variety 
Green Mountain is susceptible to the race of loose smut, while 
Monarch is resistant; in contrast, Green Mountain is resistant to 
the race of covered smut, while Monarch is susceptible. 
In the same way, duplicate sets of seed for growing 265 third 
generation progenies of Navarro X Hull-less were inoculated 
with Races 1 of loose and covered smuts. Navarro is resistant to 
both races of smut, while Hull-less is susceptible. In this hybrid, 
the data indicate that the inheritance of resistance to loose smut 
depends upon two independent factors, while inheritance to the 
covered smut depends upon three such factors. 
There were 165 third generation progenies of Navarro X Goth- 
land inoculated with Race 1 of the loose smut. Gothland is sus- 
ceptible to this smut, while Navarro is resistant. In this hybrid, 
the data indicate that the inheritance of resistance is dependent 
upon two independent factors, the results corresponding with the 
hybrid Navarro X Hull-less inoculated with the same race of 
loose smut. | 
Altogether, there were grown 151 third generation progenies 
of Navarro X Black Mesdag which had been inoculated with a 
highly specialized race of covered smut, to which Black Mesdag 
is susceptible and Navarro resistant. The data indicate that sev- 
eral factors for resistance are involved. 
