40 
morphologic appearance of the loose smut. The spores produced 
on Monarch were used to inoculate a series of oat varieties and, 
by successive inoculations over a period of years, several new 
types of smut were produced which exhibited recombinations of 
ogy, and pathogenicity. Some 
— 
factors for symptoms, morpho 
of the new covered types produced infection on Gothland and 
not on Monarch and others infected both of these varieties. 
There were also several new types of loose smut which infected 
Monarch but not Gothland, and one or more types which 
infected both of these varieties approximately 100 per cent. 
Thus, new specialized types, or races, were produced through 
hybridization, since the original race of loose smut infected only 
Gothland, and that of covered smut, only Monarch. 
Sorghum Smut Investigations 
Dr. D. Elizabeth Marcy has published, during the past year, 
the extensive data obtained on the inheritance of resistance of 
various sorghum hybrids to the loose and covered kernel smuts. 
In these particular hybrids two types of resistant varieties, 
Feterita and Dwarf Yellow Milo, were crossed with susceptible 
varieties. These publications were accepted as a thesis for the 
degree of Doctor of Philosophy at Columbia University. 
The experiments on the effect of temperature, moisture, and 
sucrose solution on the infection of Black Amber and Red Amber 
Sorgo, Dawn Kafir, Shallu, and Feterita, with the covered kernel 
smut, were continued. Seeds of these varieties were germinated 
in sand with a moisture content of 10, 20, 30, 40, and 50 per cent. 
of the total water holding capacity. In one series, water was 
used to moisten the sand, and in another series a 2 per cent. 
sucrose solution. Constant temperatures of 15, 17.5, 22.5, 27.5 
and 30° were employed during the germination period. After 
the seedlings emerged, they were transplanted to the field, where 
they grew to maturity. 
It was found that 10 per cent. moisture was most conducive 
to high infections at all temperatures and for both the water 
and sucrose solution series. At temperatures of 15 and 17.5°, 
slightly higher infections were obtained in the water series; the 
reverse was true at temperatures of 27.5 and 30°. At tempera- 
