121 
also true that some of the smuts can not be controlled by any 
known method of seed treatment, since they are not primarily dis- 
tributed by spores present on the outside of the seed or by dormant 
mycelium in the seed. In many cases we have the very serious 
problem of soil infestation where the spores, finding lodgment in 
the soil, are the main source of producing infection in the plant. 
When the crop is planted and the conditions are favorable for 
germination of the seed of the host, the spores also germinate and 
may gain entrance. One of the chief problems in the control of 
bunt of wheat in eastern Washington and Oregon and Idaho is 
due to the fact that soil infestation occurs on an extensive scale. 
Similarly the main problem in connection with the flag smut of 
wheat, the head smut of sorghum and corn, and common corn 
smut is due to the fact that the spores live over in the soil. 
Recent Investigations of Cereal Smuts—While a great deal of 
effort is still being spent on petfecting methods of seed treatment 
for the control of the smuts which are seed-borne, recent investi- 
gations on the cereal smuts have developed along somewhat new 
lines. One important phase has been the determination of the 
exact influence of environal factors on infection. The agricul- 
turist long has known that the weather plays an important part in 
the occurrence of smuts as well as other diseases. Consequently, 
the determination of the exact influence of temperature, soil mois- 
ture, soil acidity, and other possible factors has been necessary in 
order to make further progress along some other lines of study. 
In the investigations at the Brooklyn Botanic Garden we have car- 
ried out extensive experiments with the covered smut of oats, the 
loose and covered smuts of sorghum, and the covered smut of 
barley. It has been demonstrated that infection in the covered 
smut of oats will take place over a wide range of temperature, 
from 5° to 30° C. The highest infections, however, were obtained 
x Low soil moistures, also a 
at temperatures of 20° or 25 
slightly acid soil, proved to be much more favorable for infection 
than high soil moistures or an alkaline soil. The infection of 
sorghums by the covered and loose smut will also take place over 
a fairly wide range of temperature, from about I Gatomss) C. 
Both these smuts are favored by a low soil moisture as compared 
