Aug. 15, 1914 
Head Smut of Sorghum and Maize 
367 
control plantings (plat C, Nos. 12 to 20, inclusive) were infected—two of 
them to the extent of 25 per cent or more—while the percentage of infec¬ 
tion in the successful inoculations was not remarkably greater, as com¬ 
pared with controls, than was produced by the same methods at the 
other two stations. It is thus indicated that at Amarillo, or wherever 
this smut occurs at all commonly, the parasite is present, doubtless in the 
soil, in much the same way as the common maize smut, Ustilago zeae , 
is present where maize is much grown. 
PREVENTION OE HEAD SMUT 
Since the period of infection appears to be quite indefinite, the pre¬ 
vention of this disease seems almost as difficult a problem as that of 
dealing with common maize smut, and, where prevalent, is a more serious 
question on account of the more systematic character of the infection. 
This latter fact, however, suggests a possible, though very doubtful and 
as yet untried, specific measure for prevention—i. e., the treatment of 
the soil about the seed at planting time in some such way as is done for 
onion smut—in the hope of keeping infection away from such buds as 
develop early in the life of the plant. 
The fact that the disease occurs most abundantly in a district where 
manures or fertilizers have rarely, if ever, been used obviates the expla¬ 
nation of its occurrence on this basis. The Panhandle of Texas is, how¬ 
ever, a region of high winds favorable to its spread, and the cutting out 
and burning of the whole plant when one is found infected should, of 
course, be recommended. Rotations planned to avoid continuous 
cropping of the particularly susceptible sorgo varieties on the same 
ground or to the leeward of prevailing winds from such a field should also 
considerably reduce the amount of head smut. 
An important element in the relation of the problem to the grain- 
sorghum grower is the fact that milo, as has been noted by Freeman and 
Umberger (1908), is a variety apparently immune from all the sorghum 
smuts. This crop is widely grown in the southern part of the Great 
Plains, and it should be possible, theoretically, to obtain various immune 
varieties adapted to other sections by breeding from it. Since the cause 
of this immunity is not yet apparent, however, it can not be definitely 
stated that its hybrids will partake of this character. Kafir and broom 
corn, while much less susceptible to this smut than the sorgos, are quite 
subject to the attack of the kernel smut. This lack of immunity might 
prove serious to these crops or even to maize, should the head smut ever 
become as abundant as has maize smut (Ustilago zeae) in many sections. 
The latter is indigenous to America, however, and since the head smut is 
not, it may be hoped that adequate quarantine measures would prevent 
its spread and lead, perhaps, to its final eradication. 
