The Bacterial Diseases of the Bean 51 



or in maltose broth; no gas is formed in these sugar broths; nitrates are 

 not reduced to nitrites, nor is gas formed in nitrate broth; gelatin is slightly 

 liquefied; starch is not digested; there is no production of indol; hydrogen 

 sulfide is not produced or but slightly; there is a light yellow-green turbid 

 growth in Uschinsky's solution, a slight trace of green in Fermi's solution, 

 and no growth in Cohn's solution; the thermal death-point is approximately 

 49° C. 



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

 the sieva bean (P. lunatics), and the scarlet runner bean (P. coecineus). 



A NEW BACTERIAL DISEASE OF THE BEAN, FOUND IN NEW YORK AND 



NEW JERSEY 



(Caused by Phytomonas vignae var. leguminophila n. var.) 



In August, 1926, specimens of diseased leaves of a garden variety 

 (name unknown) of Phaseolus vulgaris were received from Dr. C. Chupp. 

 These had been collected in a field in New Jersey where the disease was 

 said to be very severe. The lesions on the leaves were rather unusual in 

 appearance. They were smaller than those spots which one associates 

 with Phytomonas phaseoli or Phyt. medicaginis var. phaseolicola. They 

 were red-brown in color, and when the specimens were received in Ithaca 

 the lesions appeared to be somewhat raised above the surrounding tissue. 



In an attempt to isolate a pathogene from the spots, numerous white 

 bacterial colonies appeared in the plates. They were larger and more 

 rapidly growing than Phyt. medicaginis var. phaseolicola, and on beef- 

 extract agar they produced a green fluorescent pigment. Inoculation 

 experiments were conducted immediately to determine the pathogenicity 

 of the organism for the bean plant. In these first experiments the incuba- 

 tion period was short; infection appeared in two days when seedlings were 

 inoculated by pricking the stem, and the death of the seedling occurred 

 within a week. 



In the following year (August, 1927), specimens of diseased bean leaves 

 were again received which had been collected in the same field in New 

 Jersey. Some of the lesions on these leaves were large and of the type 

 usually considered to be caused by Phyt. phaseoli. The majority, however, 

 were small, and were similar to those described above. Nevertheless, in 

 no instance was a green fluorescent organism isolated, and in every attempt 

 at isolation, from no matter what type of lesion, Phyt. phaseoli appeared in 

 the plates in abundance. 



On September 3, 1926, diseased leaves of the yard-long bean (Vigna 

 sesquipedalis) were collected in the vegetable-garden plots on the university 

 farm at Ithaca, New York. The lesions were similar in appearance to 

 lesions caused by Phyt. phaseoli on leaves of P. vulgaris, but were somewhat 

 lighter in color. Phyt. phaseoli, however, is not pathogenic to V. sesquipe- 

 dalis. A white organism producing a green fluorescent pigment was 



