304 PRINCIPLES AND PRACTICE OF PRUNING 



pruned vines. This is because it is easier for the pruned 

 vine to supply the sugar and water, the principal con- 

 stituents of the large berries, than to produce the stems, 

 skins and seeds which make up the principal part of the 

 small fruit clusters on the unpruned vines. 



There is, of course, a limit beyond which such results 

 begin to diminish. This is due to one or both of two 

 causes; namely, the maximum sizes for berries and 

 clusters and the undue development of vegetative func- 

 tions which often cause the blossoms to drop without 

 setting fruit. The aim should be therefore to leave the 

 optimum number of buds for the production of fruit. The 

 ^_ number will vary with 



the age and individu- 

 ality of the vine, the va- 

 riety, the method of 

 training and in a n y 

 other factors. Nothing 

 will take the place of 

 experience in this mat- 

 ter. However, it may 

 be said that with vines 

 four to, sav, ten years 



FIG. 263 WIRE HOOK FOR HOLDING 11 rnfntnprr : a 1 v ; np 



VINE TO TRELLIS "" *" COimncrClal VIE 



yards, the number may 

 range in a general way between 20 and 40 buds. 



Tn general, light winter pruning increases the yield. 

 whereas heavy winter pruning makes for vigor of vine 

 and reduction of yield. Hence, it is a safe rule to leave 

 as many fruit spurs and fruit buds on mature vines of 

 normal vigor for the variety as were left the previous 

 year ; to leave fewer on weak vines, which should be 

 pruned more severely; and larger numbers on vim- <>t 

 unusually great vigor. Attempts to make weak vines 

 produce normal crops tend to augment weakness and to 

 produce inferior fruit; but by pruning to secure small 

 yield, the quality will be maintained while the vine is 



