PRUNING 75 



been thus treated bore five times as much fruit as those where 

 the cutting back had been delayed (V. 22). 



A more extensive series of experiments on apples, pears and 

 plums (126 trees in all) was carried out, in which the effect of 

 performing the cutting back on different dates was examined, 

 the examination being extended throughout nine seasons. The 

 average results during these years were 



Cut back on 



Dec. 7, Feb. 27, April 21, July 13, Dec. 7, 

 1905. 1906. 1906. 1906. 1906. 



Wood formation . 100 100 104 76 l 93 



Leaf-size . . 100 100 102 94 99 



Blossoming . . 100 102 106 Si 79 



Delaying the cutting back for a whole year has clearly been 

 somewhat disadvantageous (cf. first and last columns), but it 

 may be delayed until growth starts in the spring without any 

 detriment ; indeed, a slight benefit is indicated by the values for 

 April 21, though, owing to the variations in the different seasons 

 being large, the differences shown are within the limits of experi- 

 mental error. Delaying the operation till July, however, has 

 undoubtedly been very detrimental just as it was with the 

 lopping of older trees (p. 71) and it is remarkable that the 

 bad effect of it should persist throughout so many years : there 

 were some signs of it becoming obliterated towards the end of 

 the nine years, but, as the following details show, these signs were 

 by no means certain 



Relative Behaviour of Trees when Cutting Back had been Deferred 



till July 



1907. 1908. 1909. 1910. 1911. 1912. 1913. 1914. 



Wood formed 82 76 82 80 60 



Leaf size 90 87 96 96 99 98 



Blossoming 62 70 97 79 81 99 



The question of deferring the cutting back till twelve months 

 after the planting received still further attention in a series of 

 experiments with bush apples and pears, in which it was sought 

 to ascertain the effect, both on the roots and the branches of the 

 trees, when the latter were not cut back after the trees were 

 transplanted. By lifting the trees twelve months after the 

 planting, it was found that, in the case of apples, the omission 

 of cutting back had affected the branch-growth much more than 



1 Omitting the first year's record, when the value was 36. 



