59 
2. One parent susceptible, and the other parent resistant to the 
covered smut. There were 14 crosses between a susceptible anc 
en 
resistant variety. In 7 crosses, the resistant Feterita was com- 
bined with the susceptible Sumac Sorgo, Red Amber Sorgo, anc 
— 
Dawn Kafir. In all these cases, second generation plants gave 
47.7 to 72.1 per cent. infection. In contrast to these hybrids are 
those in which the resistant Milos are crossed with susceptible 
varieties. There were also 7 crosses of this type, Black Amber 
Sorgo, Blackhull Kafir, and Dawn Kafir, being combined with 
Dwarf Yellow Milo, Standard Yellow Milo, and Standard White 
Milo. In these hybrids, the second generation plants gave 8.1 to 
17.1 per cent infection. It is evident from the results that the 
resistance of TFeterita to covered smut 1s different from that of 
the Milo varieties. 
— 
3. Both parents susceptible to the covered smut. There were 
two hybrids between susceptible varieties, Blackhull Kafir and 
Dawn Kafir, being crossed with Red Amber Sorgo. The second 
generation plants contained 61.9 to 67.5 per cent. of smutted 
plants. 
A series of third generation progenies belonging to four dif- 
ferent hybrids was inoculated with the covered smut. In every 
case, these progenies were descended from the surviving second 
generation plants which had been inoculated with this smut in 
the previous year. There were 10 third generation progenies of 
Dawn Kafir & Red Amber Sorgo, both very susceptible varieties. 
The second generation plants in the previous year gave 50.9 per 
cent. infection. All of the 10 third generation progenies con- 
tained infected plants, the percentage varying from 20 to 95. 
There were 30 third generation progenies of the hybrid of Black 
Amber Sorgo & Dwarf Yellow Milo, the former being very sus- 
ceptible, while the latter 1s resistant. Three of these progenies 
proved to be completely resistant, 23 gave from 5.2 to 26.6 per 
cent. infection, and 4 gave 42.1 to 60.0 per cent. 
There were 30 third generation progenies of the hybrid Feterita 
x Dwarf Yellow Milo. Both of these varieties are very resistant 
and, as noted above, the second generation of this cross gave en- 
tirely negative results. It was found, however, that 5 of the third 
generation progenies contained infected individuals, the percentage 
