12 
Colorado Agricultural College 
and Paniciim grasses. This phase of the work will be studied further 
the coming season. 
Millet growers are in further danger of introducing smut by the 
use of seed imported from without the State, since large amounts of 
millet are imported into Colorado annually. 
EFFECTS OF FORMALDEHYDE GAS UPON SPORES 
In order to measure the effectiveness of formalin gas in destroy¬ 
ing the germinative power of smut spores, a sterile cage measuring 
28x34x32 inches was prepared. Three cubic centimeters of formalin 
gas was atomized within it and spore suspensions in water were in¬ 
troduced and allowed to stand 4, 6, and 12 hours, and then removed 
In no case, were any of the spores observed to germinate. Water cul¬ 
tures of spores from the same source and placed under the same con¬ 
ditions, except that no application of formalin gas was made, yieldeo 
abundant germination of spores. Frequent trials of this treatment 
demonstrated beyond any doubt the effectiveness of the formalin gas 
in destroying the viability of the spores. 
FACTORS AFFECTING VITALITY AND GERMINATION OF 
SPORES 
The length of life of millet smut spores has not been studied 
fully. Our studies thus far show that spores are capable of a high 
percentage of germination after a period of three years. Undoubtedly, 
the viability lasts for seven or eight years, altho it is likely that it is 
seriously impaired at the end of such periods. Spores which were 
collected 27 years ago could not be made to germinate in water or 
nutrient cultures. Spores taken from smutted heads just after they 
had emerged from the leaf sheath were found to germinate readily in 
distilled water, thus requiring no resting period before germination. 
The lasting viability of the smut spores disproves the theory held 
by some people that the storing off seed for a few years results in 
ridding it of the liability to smut. This practice should, therefore, 
be discontinued because the viability of smut spores is certain to out¬ 
last that of the millet seed. 
Little can be said at present regarding the effects of moisture and 
temperature and other soil factors upon spore germination and infec¬ 
tion in the soil. Temperature conditions prevailing at the time the 
seed and smut spores germinate may determine whether an attack will 
result or not. It has been shown in stinking smut of wheat that late 
sowing results in a greater percentage of smut in the crop than does 
early sowing. This is explained on the basis of low resistance of the 
