The Bacterial Diseases of the Bean 33 



On the seeds 



The symptoms produced by Phyl. flaccumfaciens on the seeds of beans 

 are practically the same as certain of those produced by Phyt. phaseoli. 

 The bacteria entering the seed through the vascular system may produce 

 a yellow spot on the hilum. If infection is more severe, the organisms 

 spread out underneath the seed coat and discolor the seed. If the seed is 

 white, infection with this pathogene may turn it a bright yellow. Severely 

 infected seed may be very wrinkled and appear as if varnished. 



INOCULATION EXPERIMENTS 



All of the symptoms described above have been produced on the Red 

 Kidney bean in the greenhouse by artificial inoculation. Infection always 

 is obtained at a temperature of 80° F., provided the plant is injured and 

 the injury extends into the fibrovascular bundles. Red Kidney is very 

 susceptible and is one of the best varieties to use for inoculation purposes. 



Cross-inoculation experiments were conducted on thirteen species of 

 legumes, eight of which proved to be highly susceptible. Phytomonas 

 flaccumfaciens thus appears to have a particularly wide host range, and 

 there are, no doubt, other susceptible species which are still unknown. The 

 inoculations were made by injuring a seedling or a young, vigorously 

 growing plant on the stem, and introducing the pathogene at the same 

 time. The symptoms resulting on the susceptible species were more or 

 less similar to those appearing on the common bean (Phaseolus vulgaris)] 

 that is, a wilt occurs, either of the entire plant or of a part of it. Phyt. 

 flaccumfaciens remained in all cases a vascular parasite. The susceptible 

 species are as follows: sieva bean (P. lunatus), scarlet runner bean (P. 

 coccineus), adzuki bean (P. angularis), cowpea (Vigna sinensis), yard-long 

 bean (V. sesquipedalis) , soybean (Glycine max), and hyacinth bean (Dolichos 

 lablab) . 



Negative results were obtained with the following species: white- 

 flowering lupine (Lupinus polyphyllus) , kudzu vine (Pueraria hirsuta), 

 broad bean (Vicia faba), field pea (Pisum sativum var. arvense), and sweet 

 clover (Melilotus alba). Since infection always was obtained when suscep- 

 tible species were inoculated, it is felt that this list is correct under the 

 conditions used. When infection was not obtained at the first inoculation, 

 as on these five species, the experiments were repeated two or three times. 

 These inoculations involved from twenty-five to fifty individuals in all. 



ETIOLOGY 



Miss Hedges (1926) has already published a very excellent description 

 of this organism, and the writer's description, presented here, is included 

 principally to give opportunity for a comparative study with the other 

 bacteria which cause blights on beans. Ten strains isolated from various 

 places in New York State were used in preparing the following description. 



