Abscission of Flowers and Fruits of the Apple 



79 



In all cases the limbs that received relatively little sap had a smaller 

 percentage of fruit-setting spurs than those receiving an abundant supply 

 of sap. In a case not recorded in the table, members of a pair of branches 

 on a Strawberry tree were left untreated. One arm had 1064 flower- 

 bearing spurs, and the other arm had 1155. The percentage of spurs 

 setting fruit was 22 for the former and 22.2 for the latter. The untreated 

 limbs in lots 3 and 4, table 31, produced fruit on 20.4 and 23.8 per cent, 

 respectively, of their spurs. These figures would seem to indicate that 

 the range of variation in the percentage set is only slight when large 

 numbers of spurs are involved. 



As previously shown, the lateral growth produced by a flower-bearing 

 spur may be taken as an index to the sap supply to that spur. In order 

 to determine whether the treatments given had the desired effect of 

 increasing or decreasing the sap supply, the lateral spur growth was 

 carefully examined in each case. The analyses of the lateral growth 

 produced by fifty of the largest flower-bearing spurs from a pruned branch 

 and an equal niimber from an unpruned branch of a Strawberry tree 

 are recorded in table 3 2 : 



TABLE 32. Lateral Growth Produced by Flower-bearing Spurs from a Pruned 

 Branch and from an Unpruned Branch 



Amount of lateral growth 



Produced by 



spurs from 



pruned branch* 



Produced by 



spurs from 



unpruned branch t 



2 leaves 



3 leaves 



0.5-5 centimeters 



5. i-io centimeters- 



Over 10 centimeters 



Average weight of lateral growth 



5 

 6 



31 



4 

 4 

 2 . 68 grams 



17 

 19 

 10 



3 

 I 



1 . 90 grams 



* 37.4 per cent of the flower -bearing spurs produced fruit, 

 t 20.4 per cent of the flower-bearing spurs produced fruit. 



The spurs from the pruned branch made a more vigorous lateral growth 

 than those from the unpruned branch. This indicates that the pruning 

 actually increased the amount of sap available for each spur on the treated 

 branch. The observations made in the remaining cases showed that the 

 limbs which set most fruit to the hundred spurs also produced .the most 

 vigorous lateral spur growth. 



The percentages of large and of small spurs setting fruit on the limbs 

 that received relatively little sap to the spur, and on those that received 

 relatively much sap to the spur, are recorded in table 33. The spurs 

 were classed as large if they were produced from buds that were terminal 



13 193 



