June. 1933] Pollination and Fruit Setting in the Apple 5 



The need of cross-pollination is thus a relatively new discovery following 

 in the footsteps of commercialization of the apple industry. Since the time 

 Waite attempted to discover what effects the self and cross-transfer of pol- 

 len would have on the resulting fruit, it has heen determined that the 

 amount of fruit setting on the various varieties can be increased through 

 cross-pollination by many other sorts and that, in most cases, this is a very 

 necessary consideration. 



To determine the list of suitable pollenizers for the various cultivated 

 sorts, certain experiment stations have conducted pollination tests. The re- 

 quirements of some of the older sorts have been pretty well worked out, but 

 there will always be the necessity for determining the requirements of new 

 varieties as they are developed, and likewise the efTectivenss of new varie- 

 ties as pollenizers for the older ones. 



The experiment station may save growers much time by recommending 

 quality orchard varieties that will poUenize one another satisfactorily. With 

 a list of such varieties and some idea of the degree of coincidence in their 

 blooming dates, the grower should be able to pick desirable combinations. 

 It is to be assumed that he will exercise some judgment in choosing varie- 

 ties with relation to market demands, climatic and regional adaption and 

 other points related to profitableness. 



II. Flower Bud Formation and Development 



Inasmuch as the set of fruit is intimately connected with the blossom 

 (the apple fruit being formed from the basal portion of the flower), it is 

 very essential to keep the tree in such a state of vigor that it will produce a 

 plentiful supply of strong flower buds. 



The first essential is that the tree be grown properly. A strong frame- 

 work, proper fertilization of the soil and good management of water- 

 supply are necessary. When the tree has reached the age to produce flower 

 buds, attention must be paid to this process. Without these, or with the 

 formation of only weak ones, no fruit will result. 



The flower-cluster buds on the apple tree are produced principally on 

 short growths or shoots called spurs. With some varieties flower-bud clus- 

 ters are also formed at the tips of new shoots or in the axils of the leaves 

 of new growth. In any event this is a summer development preceding 

 blossoming. 



Microscopic examination of buds on spurs of the Baldwin and Mcintosh 

 has shown that in New Hampshire the first stages of flower-bud differenti- 

 ation can be detected from the middle to the last of July.* At this time 

 with the aid of the microscope, buds that are going to form only leafy 

 shoots or spurs may be readily told from those that have the possibility of 

 ultimately forming fruits. It must be remembered that for the buds to ma- 

 ture into good blossoms and fruit, favorable conditions must be maintained 

 for their continued development. 



* E. J. Rasmussen. The period of blo-ssom-bud differentiation in the Baldwin and Mcintosh 

 apples. Amer. Soc. Hort. Rci. Report 26-255-260 (1929). 



