50 BULLETIN 1284, U. S. DEPARTMENT OE AGRICULTURE 
Natal, South Africa. It, ' however, probably is identical with Soro- 
sporium reilianum (Kiihn) McAlpine. 
" The remaining three species are widely distributed in the sorghum- 
growing areas of the world. Sphacelotheca sorghi (Link) Clinton is 
coextensive with the cultivation of sorghum. It is the most destruc- 
tive disease of this crop, annually causing heavy losses in China, India, 
Africa, and the United States. Sphacelotheca cruenta (Kiihn) Potter 
appears to be less widely distributed, perhaps in part because it has 
been confused with the preceding species. Sorosporium reilianum 
(Kiihn) McAlpine is especially interesting because it occurs on both 
sorghum and maize. It causes some loss to sorghum in certain parts 
of India and in the Great Plains area of the United States. It is 
destructive to maize in Australia, South Africa, and in certain parts 
of India. It has been reported as an important disease of this crop 
in Washington, and it occurs in California. 
The present investigations were undertaken primarily to determine 
the varietal resistance of sorghums to covered kernel smut {Sphacelo- 
theca sorghi (Link) Clinton). The experiments were conducted at 
the folio-wing stations: Columbia, Mo. (four years, 1915 to 1918); 
Manhattan, Kans. (six years, 1916 to 1921); Amarillo, Tex. (four 
years, 1916 to 1919) ; Arlington Experiment Farm, Rosslyn, Va. (one 
year, 1920); and Brooklyn, N. Y. (one year, 1921). Observations 
also were made on the behavior toward Sorosporium reilianum (Kiilm) 
McAlpine of the sorghum varieties grown at Amarillo. 
In the course of the experiments with covered kernel smut, varieties 
of all the different groups of sorghums, including practically all of 
agronomic importance, have been grown. Many of the varieties 
have been represented by several different strains obtained from 
various sources. A few sorghums, mostly hybrids not definitely 
referable to any of the recognized groups, also have been grown. The 
results may be summarized as follows: . 
(1) All the strains of shallu proved to be very susceptible. 
(2) As a group, the sorgos were found to be susceptible and generally had 
high percentages of infection. 
(3) Sudan grass appears to be only moderately susceptible. 
(4) The three varieties of broomcorn have proved to be moderately susceptible 
to covered kernel smut. The highest percentages of infection obtained were as 
follows: Acme, 37.2 per cent, at Brooklyn; Dwarf, 20.4 per cent, at Amarillo; 
and Standard, 40.8 per cent, at Columbia. A strain of Standard, Missouri No. 
198, showed 45.5 per cent infection, but only 11 plants matured, so that the 
numbers are not large enough to be very significant. 
(5) Shantung, a dwarf brown kaoliang, has proved very resistant, as only 
two plants out of a total of 1,845 were infected, and there is some question as 
to the identity of these. Most of the Brown kaoliangs showed low percentages 
of infection except at Brooklyn. Barchet, Blackhull, Manchu, and Mukden 
White are susceptible varieties. 
(6) The kafirs have all proved to be very susceptible. 
(7) The two varieties of durra, Brown and White, which have been grown in 
the United States for several years, have proved to be very susceptible. Some 
recent introductions of White durra have shown a high degree of resistance. 
(8) The four varieties of milo have shown very marked resistance. A total 
of 4,529 plants of Dwarf Yellow milo, 2,074 of Standard Yellow milo, and 144 
of Dwarf White milo were grown, and no infected plants were observed. Three 
infected plants of Standard White milo out of a total of 2,256 were observed. 
It is possible that at least two of these infected plants belong to some other 
variety of sorghum. There can be no doubt, however, as to the identity, of the 
infected Standard White milo plant observed at Amarillo. 
(9) Feterita has proved to be very resistant. A total of 3,638 plants has been 
grown at the different stations and only 7 have been infected. Some of these 
may not have been pure feterita. 
