CEREALS 335 



such manure is applied. The smut itself, contrary to 

 popular belief, is poisonous only under very rare and ex- 

 ceptional conditions, so rare as to be practically negligible. 

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

 This smut, identical with that of sorghum, occasionally 

 occurs upon corn and is somewhat more injurious than the 

 usual corn smut. 



Corn Ear Rots 



Four types of ear rot due to four distinct diseases 

 are described below. In the aggregate the loss from 

 these is enormous, constituting as it does 10 per cent 

 or more of a crop worth annually more than $125,000,000. 

 The infection resulting in this loss comes from definite 

 species of fungi, and is not comparable to ordinary molding 

 of dead organic matter by fungi of varying kind. These 

 corn ear rots are true definite diseases. Ninety per cent 

 of these rots is caused by one species of fungus alone, 

 and its vulnerable points of attack are known. 



Dry rot {Diplodia Zece (Schw.) Lev.) and (Diplodia 

 macrospora Earle). — This is one of the very widespread 

 dry ear rots of corn variously known to growers as mold, 

 mildew, rot, dry rot, etc. Suspicion has been recently cast 

 upon it as the cause of pellagra.^ 



Though the disease is really present soon after silking, 

 and even much eariier from root infection, it is not usually 

 recognized until husking, when a whitish covering of the 

 kernels within the husk is noted. This white mycelium 

 also forms dense masses between the individual grains, 

 among the husks, and over the cob. The grains on the 



> Smith, E. F., and Hedges, Florence, Sci. n. s. SO, 60, July 9, 1909. 



