378 FUNGOUS DISEASES OF PLANTS 



fungus will multiply itself and be returned to the land in a form 

 to do considerable damage to the crop the following season. It is 

 commonly stated that fields heavily fertilized with barnyard manure 

 develop a higher percentage of smutted corn. 



V. SMUT OF BLUE-STEM GRASS 

 Sorosporium Syntherismce (Pk.) Farl. 



For the most part, the various species of Sorosporium occur 

 upon the so-called blue-stem and poverty grasses, belonging to the 

 genus Andropogon and Aristida. Several species are therefore 

 common but of slight economic importance. Sorosporium Synthe- 

 rismce is found, however, upon several species of Panicum and 

 Cenchrus, and is quite widely distributed throughout the United 

 States. The sori are usually confined to the inflorescence, the 

 whole of which may or may not be affected. At maturity they are 

 inclosed in a false membrane, somewhat similar to that in Ustilago 

 Ze&, which ruptures, exposing the spore masses and shred-like 

 remnants of host tissue. The spores adhere together in spore balls 

 for a relatively short time, the balls being usually variable in shape, 

 measuring from 50 to ioo/u, in length. The spores are spheroidal 

 or irregular in outline, measuring 9 to 1 3 /i, and they are covered 

 with minute wart-like projections. 



VI. TOLYJ'OSPORirM BULLATUM (Schroet.) Schroet. 



The above species is probably the most widely distributed of 

 this genus in the United States. It occurs upon the common barn- 

 yard grass (Echinochloa crusgalli}. The sori are confined to the 

 ovule sacs, and, as in the preceding species, they are covered with 

 a membrane which upon being ruptured exposes the spore balls. 

 Tin- latter are from 50 to 160/4 in length, black and opaque, con- 

 sisting of one hundred or more closely united spores. The spores 

 appear flavous or reddish brown. According to Clinton they are 

 "covered with a thin, tinted, outer coat, more or less folded in 

 ridges, by which the spores are bound together, and which, on the 

 rupturing of the spore balls, often show as spiny projections at the 

 spore margins, usually ovoidal, spherical, or polyhedral, 7 to 12 /x." 



