New York Agricultural Experiment Station. 387 



on one tree which were known to have been hit by the spray 

 39, or 87 per ct., set no fruit. Out of 49 corresponding blossoms 

 which were not sprayed 26, or 53 per ct., did not set fruit. In 

 this case probably the blossoms had not been open so long as in 

 the following two cases. 



On another R. I. Greening tree 48 blossoms were marked as 

 hit by the spray of which but 3, or 6 per ct., failed to set fruit 

 while 25 out of 50 blossoms which were not sprayed, or 50 per 

 ct., did not set fruit. 



On a Baldwin tree 50 blossoms were marked as hit by the 

 spray, of which 31, or 62 per ct,, failed to set fruit while 32 out 

 of 47 unsprayed blossoms, or 68 per ct., set no fruit. 



In the tests with the Hurlbut and Jefferies and in one test 

 with R. I. Greening the sprayed blossoms were nearly always 

 ruined by the treatment. In one test with R. I. Greening and 

 in the test with Baldwin the treatment reduced the percentage 

 of fruit which set but little if any below the percentage which 

 set on unsprayed portions of the tree. These experiments sug- 

 gest the idea that if the apple trees are not sprayed until after 

 the most of the blossoms have been open for several days the 

 treatment will not interfere to any considerable extent with the 

 setting of the fruit, but further experiments are required to 

 demonstrate whether or not this idea is correct. 



The processes of the opening of the blossoms and of the anth- 

 ers, the germination of pollen and the growth of pollen tubes 

 are hastened by the higher and retarded by the lower tempera- 

 tures. It cannot be stated definitely how long a time is required 

 after the blossom opens for the pollen to reach the stigma, to 

 germinate and to send the pollen tube into the style far enough 

 for it to be beyond the reach of the toxic effect of spray mix- 

 tures applied to the open blossoms. It is desirable that this 

 subject be thoroughly investigated in order that the fruit grow- 

 ers may understand when the blossoms have developed enough 

 to be out of danger of being ruined by spray mixtures. 



Apple trees sprayed repeatedly icMle in bloom. — Some tests were 

 made in the orchards at the Experiment Station in which apple 



