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MANUAL OF AMERICAN GRAPE-GROWING 



are bent over in the form of a circle and tied by their middle 

 part to a stake which may be smaller and lower than that needed 

 for the vertical canes. 



This bowing of the canes has several useful effects. The 

 change of direction moderates the tendency of the vigor of the 

 vine to expend itself only on the terminal shoots. More shoots 

 therefore are formed on the fruit canes and as their vigor is 

 somewhat decreased they tend to be more fruitful. The slight 



FIG. 25. 



Head pruning : fan-shaped head ; fruit canes tied to horizontal 

 trellis. 



mechanical injury caused by the bending operates in the same 

 direction. 



The excess of vigor thus being diverted from the fruit canes 

 causes the renewal spurs to form vigorous shoots, which soon 

 grow above the fruit shoots and obtain the light and air they 

 need for their proper development. This method is used suc- 

 cessfully for certain wine grapes such as Riesling, Cabernet, 

 and Semillon. It is unsuited to large vigorous varieties or for 

 vines on rich soil planted wide apart. In these cases two fruit 

 canes are usually insufficient and, if more are used, the grapes 

 and leaves are so massed together that they are subject to mil- 



