SORGHUM SMUTS AND VARIETAL RESISTANCE 
41 
Table 10. — Comparative susceptibility of certain sorghums to infection with head 
smut and covered kernel smut at the Amarillo Field Station 
Variety- 
Serial No. 
Head smut (Sor»sporium 
reilianum) 
Covered kernel smut 
(Sphacelotheca sorghi) 
Years 
grown 
Heads 
Infec- 
tion 
Years 
grown 
Heads 
Infec- 
tion 
S.P.I. 32384 
F.C.I. 01950 
Mo. 130 
F.C.I. 1534 
S.P.I. 17548 
Kansas station "... _ 
S.P.I. 17537 
S. P.I. 17535 
3 
1 
1 
3 
3 
1 
3 
2 
1 
Number 
1,383 
494 
1,668 
1,512 
1,810 
• 1, 745 
893 
1,414 
288 
Per cent 
8.4 
10.5 
10.1 
22.5 
22.1 
16.7 
19.3 
20.1 
12.8 
4 
1 
1 
4 
4 
2 
4 
4 
1 
Number 
944 
279 
945 
1,032 
1,444 
948 
652 
1,017 
136 
Per cent 
8.5 
Minnesota Amber sorgo 
4.6 
27.1 
Red Amber sorgo 
Do 
Colman sorgo - 
9.0 
7.4 
36.1 
11 3 
White durra 
18.2 
25.0 
In view of the fact that head smut of sorghum seems to depend for 
its occurrence primarily upon the spores in the soil, it was not pos- 
sible to be as certain of results as in the case of the seed-borne covered 
kernel smut, w 7 ith which one could be very certain of a thorough inocu- 
lation of every seed of each variety and consequently of an equal 
chance for the infection of the seedlings. Owing to the possible un- 
equal distribution of the spores of head smut in the soil, there may 
not have been equal opportunities for the infection of the different 
varieties. However, one is impressed w T ith the fact that head smut 
as a disease of sorghums appears to be very much less virulent than 
the covered kernel smut. These results compare very favorably with 
the records of "those who have observed head smut in various parts 
of the world, although Taubenhaus (108) states that head smut in 
Texas is almost as destructive as the covered kernel smut. 
EXPERIMENTS WITH MILO AND FETERITA WITH REFERENCE TO 
THEIR RESISTANCE TO SPHACELOTHECA SORGHI 
The experiments previously described afford ample evidence of 
the marked resistance of feterita and milo to Sphacelotheca sorghi 
and Sorosporium reilianum. A total of 3,638 plants of feterita has 
been grown at the different stations and only 7 infected plants were 
observed. As already stated, these infected plants may have been 
other varieties accidentally present, or they may have been of hybrid 
origin and because of their smutted condition could not be identified. 
Out of a total of 4,529 plants grown at the different stations, no 
infected plants of Dwarf Yellow milo were observed. No infected 
plants of Standard Yellow milo were observed in 2,074 plants. A 
total of 2,256 plants of Standard White milo was grown, and only 
one infected plant was observed at Columbia, one at Manhattan, and 
one at Amarillo. Only 144 plants of Dwarf White milo were grown, 
of which none was infected. 
Mention has already been made of the results reported by Kulkarni 
(64) with Dwarf Yellow milo. Kulkarni was able to obtain three 
infected heads out of a total of 635, following inoculation with spores 
of Sphacelotheca sorghi. Among the same plants he secured 50 
infected with Sphacelotheca cruenta, thus indicating the fact that the 
same lot of seed was inoculated with a mixture of spores of the two 
smuts. It is not possible fully to explain the differences in the results 
