18 SCIENCE AND FRUIT GROWING 



Where more than one variety of any kind of fruit is under 

 investigation, the experiments have to be multiplied in a corre- 

 sponding ratio. In the case of apples, pears and plums, three or 

 four well-selected varieties with distinct and different habits 

 would seem to lead to safe conclusions as to the behaviour of 

 these kinds of fruit trees under most conditions of culture ; but 

 on certain questions, such as those of pruning, a larger number 

 of varieties would be required. With bush fruits, from three to 

 six varieties may be used for experiments on general questions ; 

 and, with strawberries, about a dozen. Care should be taken 

 that none of the varieties selected are such as are known to be 

 unsuitable to the locality. 



The necessity for pruning does not raise any serious difficulties 

 in the case of bush fruits, for it is easy to adhere to some general 

 rule in the treatment of such plants ; but with the larger fruit 

 trees, the behaviour of a tree may be rendered abnormal if any 

 general scheme of pruning is adhered to too rigorously, for, apart 

 from the fact that different varieties require totally different 

 branch-treatment, individuals of the same variety will vary 

 considerably in the number of shoots formed, and the position of 

 these shoots on the tree ; and, when the shoots are ill-arranged or 

 cross each other, the trees will suffer, unless matters are remedied. 

 Still, such pruning as was left to the discretion of the pruner at 

 Woburn was always reduced to a minimum, and any rule adopted 

 as to the extent to which the main and side growths were to be 

 shortened, was adhered to in all but excessive cases. In the 

 same way, the thinning of the fruit on a tree was not left to the 

 discretion of the operator ; but consisted of reducing the number 

 of fruits in a truss to two. 



Logically, as has been said, a complete experiment should em- 

 brace the whole period from the grafting of the tree to its ultimate 

 death; but this is neither practicable, nor would the results be 

 of much benefit to fruit growers, for the economy of a fruit 

 plantation, like that of a gold mine, consists in producing the 

 highest returns in the shortest time there being, however, a 

 limit below which precocity and rapid exhaustion of the tree 

 ceases to be profitable, owing to the expense of replanting the 

 ground. So far as experiments are concerned, the life of a tree 

 may be divided into two periods : the first, during which active 

 growth is progressing, and new branches are being formed ; the 

 second, that of fruit-bearing, when growth is restricted to a 

 gradual enlargement of the trunk and main branches, and to the 

 formation of only small subsidiary shoots. A third period follows , 



