STOCKS AND RESISTANT VINES 67 



frequently more resistant than others inherently more resistant, 

 but which are not otherwise adapted to the particular condi- 

 tions of the vineyard. Species of grapes vary greatly in their 

 root systems, some having thick, others slender roots; the 

 roots of some are soft, of others hard ; some have roots going 

 down deeply, others are almost at the surface of the ground. 

 Manifestly these various root-forms are but adaptations to 

 loose and heavy, dry and moist, deep and shallow soils, or to 

 some circumstance of climate. A vine bruised by adversity 

 is in no condition to withstand phylloxera. Therefore, since 

 the adaptability of a variety to a soil or climate may be changed 

 by the stock, the adaptations of stocks to soils and climates 

 must have attention. 



Affinity of stock and cion. 



Different varieties of grapes do not behave alike on the same 

 stocks, and different stocks may affect varieties differently. 

 Even when the kinship is close, some grapes resist all the 

 appliances of art to make a successful union ; while, on the 

 other hand, quite distinct species often seem foreordained to 

 be (joined. For example, Rotundifolia, which has the highest 

 resistance to phylloxera of any species, is useless as a stock 

 because it is impossible to graft any other grape on it, while 

 Vulpina and Rupestris unite readily with varieties of Vinifera, 

 the slight decrease in the vigor of the grafted vines serving 

 oftentimes to increase fruitfulness. Something more is neces- 

 sary, then, than botanical kinship. Just what is necessary, 

 no one knows, beyond : that there must be conformity in habit 

 between stock and cion ; that the two must start in growth at 

 approximately the same time; and that the tissues must be 

 sufficiently alike that there be proper contact in the union. 

 Yet these facts do not sufficiently explain all of the affinities 

 and antipathies which species and varieties of grapes show to 

 each other. Unfortunately, the grape-grower has had but 



