216 PLANT DISEASES 



vated barley, but differs from the last in the spore-mass 

 becoming pulverent and dispersed as soon as mature. 



Very resistent to fungicides, and best treated with the 

 hot-water method, having previously been soaked for 

 several hours in cold water. 



Ustilago sorghi. Pass. Spore-mass forming in the ovary 

 of Sorghum vulgare and S. saccharatum, and completely 

 filling it with a dusty mass of spores. The anthers are 

 also attacked. As a rule all the flowers forming a head 

 are attacked. 



Ustilago cruenta^ Kiihn. This smut attacks the top of 

 the culm and branches of the inflorescence, rarely the 

 ovary of Sorghum vulgare, forming reddish-brown patches 

 and causing much distortion of the parts attacked. 



Ustilago reiliana^ Kiihn. Attacks Sorghum vulgare and 

 S. hahpense, and Zea mays in different parts of the world. 

 The ear is attacked, the spore-masses roundish or elongated, 

 at first enclosed inasilvery white membrane, then pulverulent 

 and soon dispersed, leaving only the more persistent parts 

 of the ear as a skeleton. Brefeld has experimented with 

 this species, and discovered that the spores germinate in 

 a nutritive solution after being kept for eight years. The 

 secondary spores also, if kept dry, retain the power of 

 germinating for a long time. 



Ustilago emodensis, Berk. = Ustilago treubii, Solms. 

 Professor Solms Laubach has given an interesting account 

 of this parasite Ann. Jard. Bot. Buitenzorg, vol. vi. p. 79, 

 pi. ix. (1887) but has overlooked the fact that it was 

 previously described by Berkeley Hook. Journ. Bot. t vol. 



