22 THE FUNGI WHICH CAUSE PLANT DISEASE 



Bact. teutUum Metcalf.'* (Group number 222. — ^220—.) 



A short rod with rounded ends, 1.5 x 0.8 /i, before division 

 3 X 1 ju; non-motile, no flagella seen; no spores; Gram-positive; 

 agar colonies round, thin, not viscid, porcelaneous to transparent, 

 seldom over 0.5 ju. No liquefaction. Broth clouded, precipitate 

 thin or none, no pellicle. Milk not coagulated. T. D. P. 45°, 

 10 min. Opt. 17°. Aerobic, no gas. 



Beets diseased by this organism were honeycombed with pockets 

 filled with a viscous fluid, a practically pure bacterial culture. 

 The vascular tissue was not rotted. Inoculation by pricking the 

 bacterial exudate into healthy beets resulted in typical disease. 

 Pure cultures isolated by use of cane-sugar-agar gave similar results. 

 Three weeks after inoculation the exudate-forming pockets were 

 typically developed. Surface inoculation failed and there is no 

 evidence that the organism can infect except through wounds. 

 No rotting followed inoculation on potato, white turnip, radish, 

 tomato, or apple. 



Bact. pini Vuill.^ was found in tissue of pine galls and regarded 

 as their cause. 



Bact. fici Cav.''^ is reported as the cause of a disease of figs. 



Bact. scabigenum Busse & v. Faber is described as the cause 

 of scab of sugar-beets in Germany.*^ 



Pseudomonas Migula (p. 18) 



Short or long rods motile by polar flagella, fig. 10, whose num- 

 ber varies from one to ten but is most commonly one. Endo- 

 spores are sometimes present. The cells in some species adhere 

 to form short chains. The basis of separation into species is the 

 growth upon gelatine, character of the colonies, chromogenesis 

 and numerous other cultural characters.'^' ''• '* 



Something over seventy-nine species are known, at least fifteen 

 of which cause diseases in plants, some of them very serious. 

 Many other species occur in water, soil and manure, while others 

 are suspected animal pathogens. 



One prominent group of plant pathogens,*^ the yellow Pseudo- 

 monas group, contains, according to Smith, Ps. campestris, Ps. 

 phaseoli, Ps. hyacinthi, Ps. stewarti, Ps. juglandis, Ps. vascularum, 

 Ps. dianthi, Ps. amaranti, Ps. malvacearum. These, he says, 



