22 
Colorado Agricultural College 
SUMMARY 
Smut is the chief disease affecting millets in the Great Plains 
states. 
Two different smuts affect millet; the Foxtail varieties are at¬ 
tacked by Ustilago cramen, and the Panicum millets attacked by 
Ustilago panici-miliacei, both of which infest the individual grains, 
converting the whole head or panicle into a large black mass, enclosed 
by bracts in the Foxtail millets and by a thin, white membrane in the 
Panicum types. 
Experiments in the field demonstrate the possibility of infecting 
plants by inoculating the seeds with spores of the smut. 
Smutted plants are difficult to recognize in the field, except by 
careful examination. This accounts for the fact that smut most al¬ 
ways escapes notice in the field. 
The spore masses are enclosed by the glumes (Foxtail) or by a 
thin membrane (Panicum) which prevent spore dissemination before 
harvest. ' ( , > j 
Generally only the lower parts of the glumes are destroyed in 
Foxtail millets, while the ovary is entirely destroyed. In Panicum. 
millets, affected heads are shortened and resemble a dark, thickened 
boil. 
The injurious effects of formalin gas upon the germination of 
spores was fully demonstrated. Spores in water cultures subjected 
to the gas for 4, 6, and 12 hours, failed to germinate in all cases. 
The viability of smut spores lasts fully three years and probably 
much longer. 
The period of infection is restricted to a brief stage in the early 
growth of the plant. 
Spore dissemination in the field is effected at least to some ex¬ 
tent by a small beetle, (Phalacrus politus Mels). Other means of 
disseminations are wind, rain, and the harvesting and threshing of 
grain. 
Seed treatment is required in order to free the grain from smut. 
Seed may be thoroly cleaned by means of formalin disinfection. A 
solution of I pint of formalin to 40 to 45 gallons of water is recom¬ 
mended for treatment. 
