CAUSES OF UNFRUITFULNESS. 303 



orchard and peach houses during the flowering period to 

 assist in the distribution of pollen. 



Another simple method of pollination of self-sterile 

 varieties is to place trusses of blossoms of a fertile variety 

 among the branches of the former on bright, sunny days. 

 Insects on the wing would then visit these trusses and 

 convey the pollen to the other flowers. Such a method, 

 of course, is only practicable in the case of a few trees. 



2. Frost. Fruit trees growing in low-lying, damp posi- 

 tions are apt to have their floral organs seriously damaged 

 by late spring frosts* It frequently happens that the 

 entire crop of fruit is lost in such a case, and unfortu- 

 nately there seems no really successful way of combating 

 the injury. The various methods in vogue for the protec- 

 tion of fruit blossoms are described in the next chapter, so 

 that we need not discuss them here. Readers who culti- 

 vate fruit trees in low, damp, or exposed positions, and 

 who fail to secure good crops of fruit must therefore not 

 attribute the loss to sterility of the blossoms alone, as 

 frost and cold winds <may, in such a case, be the real causes. 



3. Faulty Pruning. The failure of trees to produce 

 flowers or fruit may often be traced to faulty pruning. 

 Trees are often planted in positions unsuitable for enabl- 

 ing them to attain their natural fruiting size, as standards 

 in small gardens, or espaliers or fan-trained trees on low 

 walls or fences. To keep these trees within the required 

 limit of space severe pruning of the shoots is practised 

 annually, with the result that they make rank annual 

 growths, which fail to ripen and develop fruit buds. This 

 erroneous practice, moreover, encourages excessive root 

 production, and makes matters still worse. Strict atten- 

 tion should therefore be paid to the instructions given in 

 the chapters on pruning and training. Moreover, care 

 should be taken not to plant trees in positions where they 

 are unable to develop to their nonmal size. Judicious 

 periodical root pruning is also essential to maintain a due 

 balance between root and branch growth. 



