Abscission of Flowers and Fruits of the Apple hi 



is desirable because only cross-pollinated flowers would mature fruits 

 and seeds on such trees. Cross-pollinated seeds would tend to produce 

 more variable seedlings, and it might be expected that desirable variations, 

 from the species' standpoint, would occur. 



From man's standpoint, however, self -fertile varieties, or those that 

 can mature fruit without strong seeds, are more desirable because there 

 are more chances of a crop if the necessity of cross-pollination can be 

 eliminated. So far as is known in the case of the apple, the presence 

 of seeds has no effect on the quality of the fruit. Seeds affect the size, 

 but size can be produced without the aid of seeds. It is conceivable 

 that a tree bearing a heavy crop of many-seeded fruits is being devitalized 

 to a far greater extent than another tree of the same variety bearing a 

 crop of fruits equally heavy but having relatively fev\^ seeds. This hypoth- 

 esis presupposes that the production of seeds requires more energy and 

 food than the mere production of the flesh of the fruit. 



The problem, then, it seems, is to find cultural treatments that are 

 favorable to self-fertility. This is by no means a simple problem. One 

 should not expect, for example, that the soil treatment which proves 

 favorable for one or more varieties will prove favorable for all. Any 

 treatments, however, that produce relatively long spur growth and provide 

 for an abundance of stored food, and any treatments that influence the 

 vigor of the individual spur, may be expected to be favorable for the 

 development of blossoms into fruit without cross-pollination. Unfavorable 

 climatic conditions may be involved in the self -sterility of a given variety ; 

 if such is the case, nothing can be done but to make the best provisions 

 for cross-pollination. 



The observations and experiments recorded in the preceding pages 

 justify the tentative conclusion that unfavorable conditions of nutrition 

 and water supply are among the basic factors which cause the normal 

 drop of flowers and partially developed fruits of the apple. All factors 

 that have a direct or an indirect influence on nutrition and water supply 

 of the flower and the fruit, such as pollination, weather, cultivation, 

 and the like, are of importance. Fruit development, however, is possible 

 without cross-pollination and even under relatively unfavorable weather 

 conditions, so long as the young fruit has an abundant supply of water 

 and of readily available food. 



i5 225 



