Cereals 283 



Net-blotch ^^^ {Helminthosporium teres Sacc). — First 

 known in the United States in 1907, this disease has been 

 observed in Iowa, South Dakota, Minnesota, and Sas- 

 katchewan. 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 brown and lacks strength. 



Scab, Powdery-mildew, Yellow-stripe-rust. See wheat. 



BROOM CORN 



Kernel-smut''''- (Sphacelotheca sorghi (Link) Clinton). — 

 Irregular, elongated branches of inferior value indicate the 

 presence of the smut. The branches are further damaged by 

 blackening occasioned by the loose spores. The seeds are 

 destroyed. Of the fields examined by Clinton in Illinois few 

 showed over 1 per cent of the stalks infected, though some- 

 times parts of a field bore as high as 20 per cent of diseased 

 stalks. Infection can occur only upon very young plants. 

 Between the times of infection and the appearance of the 

 smut masses in the panicle no signs of the disease are seen 

 without the aid of the microscope. 



The smut can be prevented by the use of clean seed, 

 obtained either from clean fields or by disinfecting the 

 seed by the hot water (58° C. (135° F.) for 10 to 15 minutes) 

 or formalin methods. 



CORN, TEOSINTE 



Smut^^'^ (JJstilago zea (Beckm.) Ung.). — Corn smut is 

 well known to every farmer, occurring wherever the corn 

 plant is grown, as black, pulverulent masses most conspicuous 

 upon the ear and tassel. The damage in 1917 is estimated at 

 108,000,000 bushels. In Iowa a loss of two-thirds of the crop 

 was at one time reported. 



Corn smut is first mentioned in literature in 1754, and 

 the first record of it in America is in North Carolina in 

 1822. Experiments looking to its prevention were made 



