60 POMOLOGY 



that fruit-buds are formed (in the case of biennial bearers), 

 and it may also be inferred that the total leaf area of the tree 

 is greater in the non-bearing year. 



54. Effect of leaves on parts immediately surrounding 

 them. — Carefully conducted experiments under widely 

 different climatic conditions have established the fact that 

 formation of fruit-buds depends to a large extent on the 

 leaves innnediately adjacent to them. However, a state- 

 ment does not explain this fact nor does it imply that all 

 buds adjacent to leaves are developed into fruit-buds. In 

 the case of apples, for example, the larger number of axillary 

 buds are leaf-buds, and with the stone-fruits many such 

 buds give rise to a leafy shoot. The work of Magness,^ 

 however, has shown that buds are not likely to become dif- 

 ferentiated into fruit-buds unless the leaves immediately 

 adjacent to or subtending them are intact. Varieties of 

 plum and apple that are likely to fonn axillary fruit-buds 

 were treated by defoliating the alternate leaves along 

 the current season's shoot. As a result, fruit-buds were 

 formed only at the nodes where the leaves were not 

 removed. 



In the case of defoliated spurs, the results were more va- 

 riable, but the tendency was much the same as in the case 

 of the new shoots. 



In line with these observations, the work of Jones- is sig- 

 nificant. He calls attention to the large storage of reserve 

 materials in the maple tree. Since all the carbohydrates 

 are manufactured in the green leaves under the influence 

 of sunlight, the sugar-content of the sap depends on the 

 conditions of the preceding season as to sunlight and leaf 

 development. He has stated that in recent years there has 



1 Magness, J. R. Ore. Agr. Exp. Sta. Bull. 146. Harvey, E. M., and 

 A. E. Murneek. Ore. Agr. Exp. Sta. Bull. 176. 1921. 



2 Jones, C. H., et al. Vt. Agr. Exp. Sta. Bull. 103. 



