330 DISEASES OF ECONOMIC PLANTS 



Black stem rust {Puccinia graminis Pers.). — Identical 

 with that on wheat, this rust can be readily transferred 

 from either host to the other. See wheat. 



Scab {GibhereUn) . See wheat. 



Yellow leaf disease {Helminthospormjn gramineum R,bh.). 

 — This leaf blight was discovered in America by Pammel 

 in 1890. It is characterized by longitudinal, yellowish 

 green spots in parallel rows upon the leaves. The plants 

 die prematurely, and the yield is thus reduced. 



Helminthosporiose {Helminthosporium sativum Pamm., 

 King, & Bakke). — First known in 1907, this disease has 

 been observed in Iowa, South Dakota, Minnesota, and 

 Saskatchewan.^ 



It occurs as brownish, circular or somewhat elongated, 

 dark spots which soon cause the leaves to turn brown. It 

 also occurs upon sheaths, glumes, spikelets, and grain. 

 The straw at harvest is dull l)rown and lacks strength. 



Powdery mildew. See wheat. 



BROOM CORN 



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

 This fungous disease of broom corn and sorghum is indi- 

 cated by the presence of irregular elongated branches of 

 very inferior value. The branches are further damaged by 

 the blackening occasioned by the loose spores. The seeds 

 are, of course, destroyed. Of the fields examined by Chnton 

 in Illinois^ few showed over 1 per cent of the stalks in- 

 fected, though sometimes parts of a field bore as high as 20 



' Pammel, King, and Bakke, Am. Phytopath. Soc, 1st Ann. Meet- 

 ing, December 31, 1909. 



2 Clinton, G. P., 111. Agr. Exp. Sta. Bui. 47, March, 1897. 



