434 FUNDAMENTALS OF FRUIT PRODUCTION 



leaf areas on the root pruned trees only 5 to 20 per cent of those on the 

 checks. Furthermore the leaves of the treated trees were smaller and 

 paler than those of the untreated trees. This check in vegetative 

 growth was accompanied by an increased formation of fruit buds; these, 

 however, were so weak that comparatively few set fruit and yields were 

 less than those obtained from trees not root pruned. 



The experimental results of these and of other recent investigators 

 do not, on the surface, agree with the opinions of many of the earlier 

 writers regarding the desirability of root pruning. The quotation 

 from Rivers, however, included with the recommendations for annual 

 or biennial root pruning one for liberal applications of manure and a 

 study of the earlier literature dealing with this subject shows that arti- 

 ficial feeding and often artificial watering was assumed for practically 

 all root pruned trees. The relatively great productivity of the root 

 pruned dwarfs of European and other gardens therefore should be re- 

 garded as due only partly to root pruning, some of the other attendant 

 practices being perhaps more responsible. 



Seldom, if ever, would the operations incident to clean culture or 

 any other system of soil management result in a root pruning as severe 

 as that contemplated in the regular practice that goes by that name. 

 Nevertheless the deep plowing of trees growing in a shallow soil or in 

 a soil that compels shallow rooting actually effects a considerable, and 

 occasionally a very severe, root pruning. This may be expected to 

 afford a temporary stimulus to fruit-bud production and at the same time 

 to check vegetative growth more or less, though either or both of these 

 direct effects may be masked by the indirect influence that the tillage 

 exerts. 



Special Pruning Practices. — Stripping, notching, ringing and girdling 

 may be considered together as a group of special orchard practices rather 

 closely related to pruning. The names used to designate them are suffi- 

 ciently descriptive to make unnecessary any further explanation of the 

 procedure involved. They are all performed with the aim of so control- 

 ling the translocation of elaborated foods that their accumulation in 

 certain parts may lead to increased fruit-bud formation and hence to 

 greater fruitfulness or to a better setting of the flowers or to a better 

 development of the fruit itself. 



The upward movement of water in the tree, of the transpiration stream, 

 is commonly thought to occur in the outer layers of the wood. Knowl- 

 edge of the translocation of elaborated foods is rather fragmentary, 

 though it is rather generally agreed that their downward movement 

 is through the phloem. Recent investigations of Curtis^* indicate that 

 no appreciable quantities of carbohydrates move upward through the 

 xylem and that such elaborated food materials as are stored in the xylem 

 move only radially in the wood. Their upward transfer is limited mainly 



