9QO MICROBIAL DISEASES OF PLANTS 



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, 

 yellowish-white to deep yellow, lobate. On potato, spreading, deep yellow be- 

 coming slightly iridescent, smooth; potato is browned. Broth thin film, slight 

 clouding and slight flocculent white precipitate. Milk slight peptonization with- 

 out 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 dis- 

 eased seed and therefore disinfection of the seed before planting is 

 recommended. 



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

 diseased 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 practiced. 



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



WILT OF TOMATO, EGGPLANT, IRISH POTATO AND TOBACCO 



Pseudomonas solanacearum Erwin Smith 



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

 potato family has been described by Erwin Smith.* The disease was 

 first observed in the Atlantic coast and southern states. In 1903 

 Stevensf and Sackett described a wilt of tobacco in Granville County, 

 N. C. and this, too, SmithJ has shown to be due to the tomato wilt 

 organism, Ps. solanacearum. Quite recently Miss Bryan has shown 

 the same organism to be the cause of nasturtium wilt. 



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, 



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

 12. U. S. Dept. Agr., Div. Veg. Phys. and Path., 1896. 



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



t "Granville Tobacco Wilt," Bull. 141, U. S Dept. Agr., Bur. Plant Industry, 1908. 



Bryan, Mary K., "A Nasturtium Wilt Caused by Bad. Solanacearum," Jour, of Agr. 

 Research, Vol. IV, No. 5, p. 451, 1915 



