Studies on the Fire-Blight Organism, Bacillus amylovorus 7 



On May 31, 1926, approximately four hundred wild-strawberry blos- 

 soms (Fragaria virginiana Duchesne) growing out of doors were atom- 

 ized with a two-days-old culture of the fire-blight organism. Ten days 

 later most of the blossoms had died, from natural causes since very 

 few had set fruit. Two blossoms were found which appeared to have 

 been killed by B. amylovorus. Cultures were made from ten blossoms, 

 including the two doubtful ones. One blossom yielded the fire-blight 

 organism. The writer is convinced, however, that very few of the 

 dead blossoms had blighted. 



The foregoing experiments substantiate the findings of Miinn (1918), 

 and give additional information on the susceptibility of flowers and 

 young green fruits of the strawberry, and on the resistance of leaves, 

 runners, and crowns, to the fire-blight pathogene. 



INOCULATIONS ON ROSE 



In conversation with Dr. L. M. Massey, of the Department of Plant 

 Pathology at Cornell University, during the spring of 1924, it was 

 suggested to the writer that the rose might be a suscept for fire blight. 

 Dr. Massey stated that he had noticed what appeared to be fire blight 

 on terminals of roses on a number of occasions, but had made no isola- 

 tions. This prompted the writer to inspect roses rather closely during 

 the growing season, and in the latter part of July, 1924, several 

 blighted terminals of climbing roses of the variety Tausendschon Were 

 found in a nursery near Rochester, New York. Isolation from these 

 terminals and reinoculation into apple shoots proved the presence of 

 Bacillus amylovorus. 



In order to test further the susceptibility of roses to fire blight, cut- 

 tings of the following varieties were rooted and grown in the green- 

 house: Tausendschon, Climbing American Beauty, White Dorothy, Dr. 

 Van Fleet, Martha Washington, Excelsior, and an escaped sweetbrier 

 of the Eosa eglanteria type growing wild about Ithaca. The results 

 obtained by puncturing the terminals with a needle dipped in a 

 seventy-two-hours-old bouillon culture of B. amylovorus, are given in 

 table 1 : 



TABLE 1. Results of Fire-Blight Inoculations on Rose Terminals, February, 1926 



After it was established that the shoots of some varieties of roses 

 could be infected, the question arose as to whether or not blossoms 



