PRUNING 71 



entered being the relative lengths of new wood formed in 1906 

 only 



May 27, July 14, 

 1905. 1905. 



125 75 



Date of Cutting Back 



Nov. 2, Mar 16, May 15, July 14 Not cut 



1905. 1906. 1906. 1906. back. 



ioo zoo (65) (19). 67 



The benefit of cutting back, when that operation is performed 

 in the dormant season, is undoubted, for the resulting growth 

 has been half as much again as where the trees were not cut 

 back (ioo : 67), and it has made no difference whether the lopping 

 was done in November or in the middle of March. When it was 

 deferred to May of the same year (1906) no advantage seems to 

 have accrued (65), and when deferred to July the results appear 

 to have been disastrous (19) ; but this may be apparent only, 

 for the wood formed in the season" was necessarily underestimated, 

 since much of it had been removed in the lopping operation 

 itself. To ascertain what is the real effect of lopping on these 

 dates we must take the trees which had been lopped on the 

 corresponding dates in the previous year, and see what growth 

 they made in 1906 ; in that case it is found that the lopping, even 

 as late as May 27, was decidedly advantageous, resulting in twice 

 as much growth in 1906 as where there was no lopping (125 167), 

 .and that even when done in July there was some slight advantage 

 75 against 67. There are various circumstances, however, 

 which render it impossible to base a comparison between trees 

 lopped in two successive years on the growth made by them 

 during the second of these years, and it is evident from such 

 other cases where comparison is possible, that delaying the lop- 

 ping till the tree is in active growth is very deleterious; thus, 

 when the trees lopped in May and July 1905 are compared, the 

 growth in 1906 is in the proportion of 125 to 75, showing that the 

 summer lopping has produced bad results, still very appreciable 

 in the following season, and, as will be seen from results quoted 

 below (p. 75), appreciable for many seasons afterwards. It is 

 probable, therefore, that the lopping in May 1905 also would 

 show to some disadvantage had there been data for comparing 

 it with a lopping done earlier in the same year. The general con- 

 clusion is that, though such lopping is effectual in restoring the 

 tree to active growth, it should be done during the dormant 

 season, and if not done before May, had better be postponed till 

 the following winter. 



