GRAPE PRUNING AND TRAINING, 



349 



that is, must be given fruit canes. It should be noted that many 

 varieties, such as Petite Sirah, which will bear with short pruning 

 when grafted on resistant roots require fruit canes when growing 

 on their own roots. In general, grafted vines require shorter prun- 

 ing than ungrafted. If pruned the same, the grafted vines may 

 overbear and quickly exhaust themselves. This seems to be the 

 principal reason for the frequent failure of Muscat vines grafted 

 on resistant stock. The cultural conditions also affect the vine in 

 this respect. Vines made vigorous by rich soil, abundant moisture, 

 and thorough cultivation require longer pruning than weaker vines 

 of the same variety. 



The normal size of the bunch is also of importance. This size 

 will vary from one-quarter of a pound to two or three pounds. It 

 is difficult to obtain a full crop from a variety whose bunches are 

 very small without the use of fruit canes. Spurs will not furnish 

 enough fruit buds without crowding them inconveniently. On the 

 other hand, some shipping grapes may bear larger crops when 

 pruned long, but the bunches and berries may be too small for the 

 best quality. 



The possibilities of development vary much with various varieties. 

 A Mission or Flame Tokay may be made to cover a quarter of an 



FIG. 290 FORMS OF HEAD PRUNING OF GRAPES 



a, Spur pruning with high trunk; b, spur pruning with medium trunk; c, half-long 

 pruning with medium trunk. 



acre and develop a trunk 4 or 5 feet in circumference. A Zinfandel 

 vine under the same conditions would not reach a tenth of this size 

 in the same time. Vines in a rich valley soil will grow much larger 

 than on a poor hillside. The size and shape of the trunk must be 

 modified accordingly and adapted to the available room or number 

 of vines to the acre. 



