362 DISEASES OF ECONOMIC PLANTS 



Treatment is not yet known. 



Scab. See wheat. 



Powdery mildew. See wheat. 



SORGHUM 



BHght (Bacillus sorghi Burr). — This blight was studied 

 by Burrill in 1883 and descril)ed in 1887. It prevails upon 

 sorghum, broom corn, Kaffir corn, and Milo maize, and 

 has been noted in Illinois, Kentucky, Iowa, Louisiana, 

 Ohio, Michigan, Nebraska, West Virginia, and District 

 of Columbia, often in serious form. The chief character 

 is irregular-shaped, elongated blotches of red, at first faint 

 orange, upon the leaves and leaf sheaths, sometimes limited 

 by the veins, and always more conspicuous on the inner 

 than the outer sides. Smaller patches later blend into 

 larger ones, and the affected parts die and finally turn black. 

 The lower sides of diseased spots upon the leaves often 

 bear red incrustations, resulting from the drying of the 

 ooze from within. The roots show the same discoloration, 

 and the outer parts of the rootlets die and become loose. 

 If only slightly diseased, the plants may attain normal size. 



Badly diseased roots are evidencec^by the yellowed tops 

 and other signs of malnutrition. In advanced stages 

 the roots give such poor anchorage that the plants may be 

 easily pulled from the ground. 



Infected stalks should be burned and such rotation fol- 

 lowed as to reUeve the infected soil of susceptible crops for 

 several years. 



Kernel smut (Sphacelotheca Sorghi (Lk.) Clinton). — 

 This smut infests the individual grains of the panicle, 

 while the head as a whole remains nearly normal in appear- 



