5 
Sorghum Smut Investigations 
Miss D. Elizabeth Marcy has continued her studies on the in- 
heritance of resistance of various sorghum hybrids to both the 
covered (Sphacelotheca sorght (Link) Clinton) and loose (S. 
cruenta (Kuhn) Potter) smuts of sorghum. Data for a large 
number of hybrids involving different types of varieties of sor- 
ghum from the standpoint of resistance and susceptibility were 
obtained. 
First Generation Plants——Since it is rather easy to secure a 
considerable number of first generation plants of sorghum hy- 
brids, it was possible to inoculate these and determine their smut 
reaction. There were seven hybrids involving the resistant 
Feterita, or Milo, with susceptible varieties, and it was found that 
the first generation plants of hybrids with Feterita, inoculated 
with covered smut, were susceptible, while those in which Milo was 
one parent were resistant. 
lirst generation plants of a cross between Feterita and Dawn 
Kafir were inoculated with loose smut and they were found to be 
susceptible. In contrast, first generation plants of hybrids be- 
tween Milo and Dawn Kafir, inoculated with the loose smut, were 
resistant. 
Second Generation Plants —There were grown 596 second gen- 
eration plants belonging to twenty hybrids, inoculated with covered 
smut. These represented three types of crosses: susceptible X 
susceptible, resistant resistant, and resistant > susceptible. 
Two crosses between susceptible varieties gave over 90 per cent. 
infection. Hybrids between the resistant varieties Feterita and 
Dwarf Yellow Milo gave a very few infected second generation 
plants (4.1 per cent.). Crosses between the resistant Milo and 
susceptible varieties gave 5.8 to 16.6 per cent. infection. On the 
other hand, crosses between Feterita and susceptible varieties gave 
42.9 to 80 per cent. infection. These results confirm the genetic 
interpretation previously made that resistance is. dominant in the 
Milo crosses and susceptibility in the Feterita crosses. In these 
experiments the susceptible parental varieties gave from 48.1 to 
6.6 per cent. infection. The resistant Milo remained entirely 
free from smut. Feterita, however, although free from typically 
smutted heads, contained from 17.8 to 44.1 per cent. blasted heads. 
