CAUSES OF UNFRUITFULNESS. 301 



CHAPTER IX. 

 Causes of Unfruit fulness. 



WE receive scores of enquiries every year from readers of 

 " Amateur Gardening," asking us to solve the problem of 

 why their trees fail to yield no, or very little, fruit. It 

 has therefore occurred to us that we might well devote 

 a special chapter to the subject of the chief causes of un- 

 fruitfulness in fruit trees, and so help to solve many pro- 

 blems that confront the amateur in his endeavour to grow 

 fruit successfully. These we will proceed to deal with 

 under various heads, as follows: 



1. Sterility of the Blossoms. Up to a. few years ago it 

 was generally assumed that the chief cause of fruit trees 

 failing to produce fruit, notwithstanding the abundant 

 crop of bk>ssom, was the result of injury by late spring 

 frosts. Now, while undoubtedly the latter is responsible 

 in some sea-sons for a paucity of fruit, scientists have dis- 

 covered that there is another cause for the failure, and 

 that is a physiological defect in the floral organs, namely, 

 the inability of the pollen grains of some varieties to pos- 

 sess the potency for fertilising the ovaries. For some 

 time, therefore, both here and in America, experts have 

 been making a close study of the subject of pollination, 

 as applied to fruit trees, and they have, as a result, dis- 

 covered that so'ine varieties of apples, pears, plums, and 

 cherries are self-sterile, i.e., incapable of fertilising their 

 flowers with their own pollen ; while others are self-fer- 

 tile and capable of self-fertilisation with their own pollen. 

 Considerable progress has been made in determining the 

 self-sterility and self-fertility of apples, plums, and 

 cherries, and also in a small degree of pears. Those 

 varieties in each class of fruit that have been definitely 

 stated to be self-sterile or self-fertile are noted in the lists 

 of varieties published in the foregoing pages. 



