The Bacterial Diseases of the Bean 29 



and in the symptomatology and in the host range there are several differ- 

 ences, the last two distinctions of which have already been discussed. It 

 is felt that these differences are probably varietal and not specific. There- 

 fore the name Phytomonas phaseoli var. fuscans n. var. is given to the 

 pathogene. 



Brief description 



Phytomonas phaseoli var. fuscans is a non-spore-forming rod with rounded 

 ends, occurring singly or in pairs. The cells measure 1.35 to 4/u by 0.6 to 

 1 .35 ju. Filaments are not uncommon. The organism is motile by means of a 

 single polar flagellum. It stains well with carbol fuchsin and gentian violet, 

 showing granules. It is Gram-negative, not acid-fast, and an aerobe. 



The colonies on nutrient agar are yellow, fairly rapid-growing, in many 

 cases with a watery-appearing zone about the edge. The edges are entire 

 to slightly undulating. The consistency of the culture is watery to butyrous ; 

 most media are colored brown; the broth is cloudy in twenty-four hours, 

 a yellow ring is formed, and the medium becomes brown at the surface, 

 the brown color extending gradually throughout; gelatin is liquefied and 

 colored brown; milk is alkaline and cleared, and later a brown pigment is 

 formed; there is no acid nor gas in dextrose, saccharose, lactose, or maltose 

 broth; starch is hydrolyzed; nitrates are not reduced to nitrites; indol is 

 not produced; hydrogen sulfide is not formed on lead-acetate agar; there is 

 no growth on Wilson's agar, in Cohn's solution, or in Fermi's solution; 

 growth in Uschinsky's solution is slight ; the thermal death-point is approxi- 

 mately 49° C. The viability of the organism in culture is not great. 



The organism is pathogenic on the common bean (Phaseolus vulgaris), 

 the sieva bean (P. lunatus), and the scarlet runner bean (P. coccineus). 



THE BACTERIAL WILT OF THE BEAN CAUSED BY PHYTOMONAS FLACCUM- 



FACIENS 



The bacterial wilt of the bean was reported first by Miss Hedges (1922), 

 who later (1926) published a fuller account of the disease. Leonard 

 (1923, 1924) also has reported on various phases of the wilt. The disease 

 is of widespread distribution in the United States, and in certain sections 

 causes considerable loss. In New York State, although it has been known 

 for some time, it has never become of as great economic importance as 

 have some others of the bacterial diseases. It does occur, however, gener- 

 ally throughout the sections growing dry shell beans, and may be found on 

 such varieties as Red Kidney, Pea, and White Marrow. 



life history 



In many respects the life history of Phytomonas flaccumfaciens is very 

 similar to that of Phyt. phaseoli. There are, however, certain differences, 

 since Phyt. flaccumfaciens is more limited in its activities on the host plant. 



The overwintering of the bacteria takes place in the seed, and in this 



