Studies on the Fire-Blight Organism, Bacillus amylovorus 41 



The writer, in an effort to test the influence of pollination and age 7 of 

 blossoms on susceptibility to fire blight, started experiments in May, 

 1925, in two orchards at Ithaca. The trees were of the Tompkins King 

 variety, from thirty to forty years of age, in sod culture, and in fair 

 vigor. Cheesecloth bags were tied over the ends of the branches before 

 blossoming, to prevent pollination of the blossoms by insects. Two series 

 of bags were used. Series I was pollinated as soon as the blossoms 

 opened, and Series II was left unpollinated. 



Both series were inoculated by atomizing a bouillon culture of Bacillus 

 amylovorus directly into the calyx cup of each blossom when the blos- 

 soms had been open for 1 to- 5, 48, 72, 96, and 120 hours. The results 

 are given in table 8. 



TABLE 8. Results of Blossom Inoculations, May, 1925 



* Majority of blossoms opened on May 15. A few center blossoms opened on May 14. 

 t Center blossoms opened on May 22. Remaining blossoms opened on May 25. 



The weather during this period was somewhat colder than normal 

 for the season of the year. The maximum and minimum temperatures 



7 "Age," as used by the writer, refers to the time that has elapsed after the opening of 

 the blossom. 



