12 A. L. PlERSTORFF 



wavy radiations, in addition to being very virulent. Upon inoculation 

 into pear shoots, ooze was produced in fifty-one hours. Martin (1921) 

 reported the production of a dark green exudate from a loquat tree 



(Eriobotrya japonica) artificially inoculated with a pure culture of 

 II. amylovorus. Examination of this ooze showed il to be highly 

 charged with fire-blight bacteria. Keinoculation into other trees failed 

 to reproduce an exudate of the same color, and Marin advances no 

 hypothesis as to the reason for this phenomenal color. 



The writer obtained a culture of the fire-blight organism from Cali- 

 fornia, and from its rapid growth on nutrient agar and the produc- 

 tion of a light yellow color he was led to think that a mistake might 

 have been made in the sending of the culture or that contamination 

 had occurred en route. However, plating the culture several times in 

 extreme dilutions, staining the organisms with differential stains, ami 

 examination under the microscope, failed to show more than one type 

 of organism. The culture was then inoculated into apple seedlings in 

 the greenhouse, and reisolation produced a similar organism. Symptoms 

 characteristic of fire blight occurred on the inoculated apple seedlings. 



These and other considerations led the writer to make preliminary 

 tests on the occurrence of strains of B. a/nvylovoriis. Cultures of the fire- 

 blight organism were obtained as follows: 



Culture Source G Isolated from Date of isolation 



A Utica, New York Apple ..._... August, 1924 



C Las Cruces, New Mexico Pear December, 1924 



( !al Davis, California Pear May (?), 1925 



CI Davis, California Apple December, 192.5 



D Ithaca, New York Apple July, 1923 



E Horseheads, New York Pear July, 1923 



F Ithaca, New York Apple July, 1924 



M Grand Rapids, Michigan Apple June, 1925 



S Columbia, Missouri Apple May, 1925 



S C Clemson College, South Carolina . . . Pear lune, 1925 



T Knoxville, Tennessee Apple May (?), 1925 



Ti Tifton, Georgia Pear May, 1926 



Inoculation tests were made with these cultures in a planting of 

 several hundred seedlings of Kieffer pear at Ithaca. The variation 

 among these seedlings in habit of growth and in taxonomic characteris- 

 tics was very noticeable, and was probably greater than exists between 

 many of our varieties of pears. A more detailed description of the 

 variation in these seedlings is given by Thomas (1927-28). 



Only trees having six or more vigorous shoots were used. Six dif- 



6 The writer is indebted to Dr. P. D. Caldis, L. M. Fenner, H. W. Fitch, Dr. L. R. Healer, and Dr. 

 I. T. Scott, for material from which some of these cultures were made. 



