BOARD OF HORTICULTUR E 169 



are deposited in this resion. Experiments at our experiment Station carried on 

 in defoliating spurs act much in the same way. In other words, those spurs 

 wliich have had their leaves taken off have lost the proper nitrogen-carl)oh.vdrate 

 balanee, and tlie spur Starts to elongate but sets no fruit bud if tlie leaves have 

 been removed early in the season. Dense shading of the spurs accomplishes much 

 the same results. because we know that sunlight is necessary to stimulate the 

 growth of the leaves and to enable the leaves to manufacture large amounts of 

 carbohydrate materials. 



Another correlation noted by Roberts was between the amount of the wood 

 growth on terminal twigs and the bearing habit of the tree. He found 



1. That terminal wood growths of eighteen inches and more in length usually 

 indicated an unfruitful tree except in trees just Coming nicely into bearing. 



2. Terminal growths of from twelve to eighteen inches seemed to indicate 

 a good balanee between nitrogen and carbohydrates, and a production of fruit 

 which was abundant and regulär. 



3. Growths from six tc twelve inches frequently meant good crops ; fairly 

 regulär, but in some cases the crops tended to be ratlier heavy one year and light 

 the next ; or what we call "alternate bearing." 



4. Terminal growths of four or five inches invariably meant weak fruit spurs 

 and poor crops. 



To sum up the findings of Roberts, fruitfulness and regularity of bearing 

 depends : first. upon a vigorous but not too vigorous growth of wood and fruit 

 spurs ; and second, upon a plentiful supply of fruit spurs especially upon two 

 year old wood, so that if each spur shall bear as often as onee in three years 

 there will be a good crop. 



Now comes the second question, how can we bring about this proper balanee 

 between the nitrogen and carbohydrate factors? In looking the matter over care- 

 fully. we see that this is not accomplished in any Single way, that there are 

 many limitiug factors to growth and production. I wish to take up briefly a 

 few of these factors before considering the matter of fertilizers. In the first 

 place, if a grower is to suceed in his orchard, whether it be with apples, pears, 

 peaches or prunes, he must be located in a climate that is suited to the production 

 of these fruits, upon soils that are naturally adapted to the various fruits he 

 has in mind, upon exposures that will not allow his fruit to be dried out if he is 

 growing berries or something of that sort. or where his fruit will not suffer from 

 late frosts in the spring, cold winds, etc. The water drainage must he good or 

 artificial drainage must be possible. 



The al)Ove factors, every fruit grower is inclined to take for granted. Several 

 others. however. are distinctly limiting in the growth of trees and the production 

 of fruit. Pruning is one of the most important of these factors. After many 

 experiments we have found it axiomatic in pruning that the greatest Stimulus in 

 pruning comes in the immediate viciuity of the cut. Bearing this in mind we 

 find that the t.vpo of cutting that seems to have the greatest influence upon the 

 formation of strong fruit buds is one that cuts out many of the small twigs and 

 branches but does not disturb the larger branches. In doing this the light is 

 allowed to reach the small twigs and fruit spurs and carbohydrates are manu- 

 factured to a much greater extent than in dense shade. 



One phase of pruning that has been overlooked to a large extent in most or- 

 chards, is that of spur pruning. This applies to prunes as well as to apples and 

 pears. Trees when older tend to load themselves up with so many spurs and so 

 much spur wood that they do not have vitality enough to set fruit upon these spurs 

 very often. In such cases the trees can be stimulated into fruitfulness by pruning 

 of some spurs entirely. and in other cases by cutting off liranches of Compound 

 spurs. This is done in the prune by cutting out many of the little twigs that 

 bear fruit spurs and allowing the light to enter to those left. Cutting out 

 occasional branches of fair size in the tops allows the sunlight to penetrate the 



