Apple Spraying Experiments in 1916 and 1917. 127 



summarized the literature on this point.* While no direct ob- 

 servations were made it is a logical conclusion that infection of 

 the pedicels of the blossoms and young fruits by the scab fungus 

 was responsible for the poor set of fruit on plot 4 in 191 7. How- 

 ever a careful analysis of the facts do not commit one to this 

 conclusion without reservations. 



The Department of Biology of the Station, for other pur- 

 poses, is now making an annual record of the yield of fruit in 

 pounds for each tree in all of the orchards. These figures for 

 the past two seasons have been turned over to the writer and 

 the average yield per tree of each plot in 1916 and 191 7 are 

 given in the last column to the right of Tables I and III. Plots 

 7, 8 and 9 of 191 6 and 8, 9 and 10 of 191 7 are made up of less 

 vigorous trees and allowances should be made in comparing 

 them with 1 to 6 in 1916, and 1 to 7 in 1917. Also the trees 

 on 5 and 6 in 1916 and 6 and 7 in 1917 are somewhat larger and 

 more vigorous, thus partially explaining the averge larger yields 

 on these plots in both seasons. There seems to be no reason, 

 however, why plot 4 in Table III should produce only 15 pounds 

 per tree while plots 3 and 5 on either side of it should yield 125 

 and 95 pounds per tree, respectively, except the probable one 

 that the fruit set on plot 4 was injured from infection of the 

 pedicels of the flowers and young fruit by the scab fungus. On 

 the other hand, the unsprayed check, plot 9, composed of much 

 less vigorous trees, lying west of plot 4 with the corners joining, 

 yielded an average of 39 pounds per tree. While it is true that 

 the relatively low yield on plot 9 may also be due partially to 

 pedicel infection by the scab fungus it is difficult to explain why 

 two ard a half times as much fruit was produced here, where 

 no fungicidal spray was applied, than was the case where one 

 out of three applications was omitted, even granting that the 

 application omitted was the all important one. Moreover only 

 40 pounds per tree were obtained on plot 10 where the records 

 show that scab was as well controlled as on plot 3 and much 

 better controlled than on plot 5. 



It will be seen on reference to Table I that in 1916 the aver- 

 age yield per tree on plot 4 on which the blossom bud applica- 

 tion of lime-sulphur and arsenate of lead was omitted was even 



*Wallace, Errett. Scab disease of apples, Bull. Cornell Agl. Exp. 

 Sta. 335:552-553. Sept., 1913. 



