and seasons. All the operations of pruning, tying, staking, etc., to 

 which a cultivated vine owes its form, are conveniently considered 

 together. 



No cultivated plant is susceptible of such a variety of modes 

 of training as the vine, and none can withstand such an amount of 

 abuse in this matter and such radical interference with its natural 

 mode of growth. On the other hand, no other plant, perhaps, is so 

 sensitive to proper treatment, or responds so readily to a rational 

 mode of pruning and training. 



OBJECTS OF PRUNING. The objects of pruning are (a) 

 to facilitate cultivation and gathering, (b) to. increase the average 

 yield, and (c) to improve the quality of fruit. The vine must not 

 be trained so high that the grapes are difficult to gather, nor al- 

 lowed to spread its arms so wide that the cultivation of the ground 

 is unduly interfered with. Vines untouched by the pruner's knife 

 bear irregularly; a year of over-bearing being followed by several of 

 under-bearing as a consequence of exhaustion caused by a too severe 

 drain on the reserve forces of the plant. The grapes on untrained or 

 improperly trained vines are exposed to different conditions of heat 

 and light, and consequently develop and ripen unevenly. 



PHYSIOLOGICAL PRINCIPLES. The main facts regard- 

 ing the physiology of the vine to be kept in mind in this connection 

 are : 



1. The vine feeds by means of the green coloring matter (chloro- 

 phyll) of its leaves. It obtains the sugar, starch, etc., which it needs 

 from the carbonic acid of the air which is converted into these sub- 

 stances by the chlorophyll under the influence of light. A certain 

 amount of green leaf surface functioning for a certain time is neces- 

 sary to produce sufficient nourishment for the vital needs of the vine 

 and for the production of a crop. Those leaves most exposed to the 

 direct rays of the sun are most active in absorbing food. The 

 youngest leaves take all their nourishment from the older parts of 

 the plant: somewhat older leaves use up more nutrient material in 

 growing than they absorb from the air. A young shoot may thus be 

 looked upon as, in a sense, parasitic upon the rest of the vine. The 

 true feeders of the vine and of its crop are the mature, dark-green 

 leaves. 



2. Within certain limits the fruitfulness of a vine or of a part 

 of a vine is inversely proportional to its vegetative vigor. Methods 

 which tend to increase the vegetative vigor of a vine or of a part 

 of a vine tend to diminish its bearing qualities, while, on the con- 

 trary, anything which diminishes vegetative vigor tends to increase 

 fruitfulness. Failure to reckon with this fact and to maintain a 

 proper mean between the two extremes leads, on the one hand, to 

 comparative sterility, and, on the other, to over-bearing and prema- 

 ture exhaustion. 



3. The vine tends to force out terminal buds and to expend most 

 of its energy on the shoots farthest from the trunk. To keep the 

 vine within practical limits, this tendency must be controlled by the 

 removal of the terminal buds, or bv measures which check the flow 

 of sap and force the growth of buds nearer the stock. 



