WILTS. 517 



system, it multiplies very rapidly and fills the water tubes with a yellow 

 slime and wilting follows. 



CAUSAL ORGANISM. The organism was first described by Stewart and later 

 named Pseudomonas steward by Erwin Smith. 



It is a short, relatively thick, motile rod with rounded ends; occurs usually in pairs. 

 No endospores observed. Stains readily with the aqueous stains. 



It grows well upon the ordinary culture media. On agar, smooth, shining, yellow- 

 ish-white to deep yellow, lobate. On potato, spreading, deep yellow becoming slightly 

 iridescent, smooth; potato is browned. Broth thin film, slight clouding and slight 

 flocculent white precipitate. Milk 'slight peptonization without coagulation; litmus 

 reduced. No gas is produced from dextrose, etc. Good growth in Uschinsky's solution . 

 Facultative anaerobe. Pathogenic for sweet corn. 



CONTROL. It is believed that the germ is disseminated on diseased 

 seed and therefore disinfection of the seed before planting is recommended. 



The disease is also spread by the use of manure which contains dis- 

 eased stalks. 



Varieties differ considerably in their susceptibility, and by the selection 

 of the more resistant kinds some relief can be secured. 



Rotation of crops and planting on new land, when available, should be 

 practised. 



Field corn and pop-corn are not affected by the wilt. 



WILT OF TOMATO, EGGPLANT, IRISH POTATO AND TOBACCO. 

 Bacillus solanacearum Erwin Smith. 



HISTORY. A bacterial wilt affecting a number of plants of the potato 

 family has been described by Erwin Smith. f The disease was first ob- 

 served in the Atlantic coast and southern states. In 1903 Stevens* and 

 Sackett described a wilt of tobacco in Granville County, N. C. and this, 

 too, Smithf has shown to be due to the tomato wilt organism, B. solan- 

 acearum. 



SYMPTOMS. The disease usually manifests itself by a sudden wilting 

 of the foliage, and, as a rule, with little or no yellowing. This may be 

 indicated at first by the collapse of a single leaf, but in time the whole 

 plant will succumb. Following the wilting, the parts affected shrivel, 



* Stevens and Sackett, "Granville Tobacco Wilt," Bull. 188 N. Car. Exp. Sta., 1903. 



f Smith, Erwin F., "A Bacterial Disease of the Tomato, Eggplant and Irish Potato," Bull. 

 12, U. S. Dept. Agr., Div. Veg. Phys. and Path., 1896. "Granville Tobacco Wilt, " Bull. 141, 

 U. S. Dept. Agr., Bur. Plant Industry, 1908. 



