364 DISEASES OF ECONOMIC PLANTS 



should be soaked in formalin, 1 pound to 30 gallons, for two 

 hours, or sprayed with the same solution and piled over- 

 night, as described for oats. The hot-water treatment, 

 134° to 142 ° F. for 10 to 12 minutes, or the usual bluestone 

 treatment, may be used if preferred.' 



Head smut (Sphacelotheca Reiliana (Kuehn) Clinton). — 

 Instead of involving the grains singly, as in the kernel 

 smut, the head as a whole is affected. A white membrane is 

 at first present, but this later breaks open, exposing the 

 pulverulent spore mass. Rarely a portion only of the head 

 is smutted. The spores soon weather away, leaving behind 

 only the veins of the part involved. This disease was 

 first noted in Egypt in 1868, and is known in abundance in 

 America only in the Texas Panhandle. 



The treatments suggested for the kernel smut are of no 

 avail in this case. The only remedy known is to avoid 

 infected seed. 



Anthracnose {Colletotrichum falcatum Went.). — This was 

 first found in America upon sorghum in North Carolina, 

 where it did considerable damage. It has since been re- 

 ported from Louisiana. It is worse upon the lowfer leaves. 

 The spots have a very definite gray or tan-colored center 

 which is surrounded by a dark, reddish brown ring, out- 

 side of which is the ordinary green of the healthy leaf. 

 As the spots age they frequently grow together and form 

 one large oblong area, sometimes several centimeters long. 

 At a late period in the development of the disease the 

 centers of the spots are occupied by small black specks, 

 the black acervuli of the causal fungus. 



' Freeman. E. M., and Umberger, H. I. C, U.S. Dept. Agr. Bur. Plant 

 Indus. Circ. 8, January 27, 1910. 



