42 



A. L. PlERSTORFF 



for 24-hour periods, together with the precipitation, are recorded in 

 table 9. 



The experiment was repeated in an orchard located near Rochester, 

 New York. The variety used was Rhode Island Greening ; the trees were 

 about fifty years old, cultivated, and in good vigor. The cheesecluih 

 bags were tied on the branches on May 21, 1925, just as the center blos- 

 soms on the south side of the trees were beginning to open. An occa- 

 sional blossom had opened, and such blossoms were removed before the 

 bag was placed on the branch. The weather on May 22 was warm, and 

 most of the center blossoms unfolded and were cross-pollinated in the 

 afternoon with Baldwin pollen. On May 23 and 24 a cold north wind 

 was blowing, but a little bud development took place. All blossoms 

 were inoculated with bouillon cultures similar to those used in the pre- 

 ceding experiment, mixed with a water suspension of fresh bacterial 

 ooze obtained from Transcendent crab-apple trees. 



The results of these two experiments, shown in table 8, indicate that 

 young blossoms are more susceptible to fire blight than are older ones, 

 and that Tompkins King blossoms are more susceptible than are Rhode 

 Island Greening blossoms. Factors other than the variety may have 

 caused the Greening blossoms to blight less frequently than the King 

 blossoms, since the inoculations were made under different weather con- 

 ditions and in different orchards. Pollination appears to have had little 

 effect on susceptibility to blight, in either the Greening or the King. 



In 1926 the experiments were continued in the orchards at Ithaca. 

 On May 28 the center blossoms of the clusters opened and were pol- 

 linated with Wagener pollen. The remaining blossoms in the 24-hour 

 series were pollinated in the afternoon of May 29. By May 30 all blos- 

 soms had opened and were pollinated. The blossoms w^vc inoculated 

 at the times indicated in table 10. On June 1, when the seventy-two- 

 hour series was inoculated, about 75 per cent of the center blossoms 

 had lost their petals. On June 2, practically all the petals had fallen 

 from the blossoms. The results were tabulated on June 14 and were 



