578 FUNDAMENTALS OF FRUIT PRODUCTION 



unfavorable action on the table and wine qualities of certain white 

 grapes, does not specify the nature of the action. 



These differences are quantitative rather than qualitative. No 

 evidence is available showing a qualitative change in fruits, in the sense 

 of an introduction or a manufacture of entirely different compounds, 

 emanating from the stocks used. Furthermore, accepting all the cases 

 alleged, there is still no clear evidence of any change beyond such differ- 

 ences as could be effected by changes in maturity. A reference to Ravaz 

 appears to show a possible relation of the stock to quality in fruit. It 

 is stated 1^^ that, "to secure high gravity must in his opinion it is stocks 

 with Riparia-like behavior which should be selected — one requires vines 

 with slow and regular vegetation, the activity of which ceases early in 

 the season. In a word, the vines should behave in as nearly as possible 

 the same way as though they were growing on a dry hillside." 



Apparently, then, the nature of the fruit the stock bears is a matter 

 of indifference; the two possibly important factors are (1) the vegetative 

 habits of the stock, (2) the congeniality of stock and cion. In the light 

 of present knowledge of the formation and ripening of fruit, it would be 

 difficult to arrive at any other conclusion. An apple is sweet or sour 

 according as it contains more or less sugar; the acid content is fairly 

 uniform. This is determined largely in the spur or the neighboring 

 branch; the trunk or roots cannot have much effect on it. The roots 

 may keep the tree growing late and so influence the ripening, but the 

 quality of the fruit the stock bears cannot be expected to influence the 

 top. A stock with good fruit but unsuitable vegetative habits might 

 influence the cion to produce inferior fruit and vice versa; a stock of a 

 sweet variety may make the fruit of a cion sweeter or more acid. 



Longevity. — It is the generally accepted view that processes greatly 

 increasing fruitfulness tend to hasten the ultimate death of the plant. 

 This opinion has ample corroboration in the dwarf apples and pears and 

 in recent years has been a very real problem to grape growers. Blunno^^ 

 mentions some instances that have a bearing here. 



"The Riparias, which are considered excellent stocks for loose, rich, deep 

 soils such as are found on river flats, have given some disappointment in a few 

 places in Sicily and Algiers," he states. "For the first few years vines grafted 

 on them are loaded with fruit, which over-production seems to exhaust the 

 plant. . . . 



"Similarly the Riparia X Rupestris No. 3306, which is generally planted in 

 practically the same classes of soil as the Riparias and the R X R No. 3309, in 

 soils a little stiff er, have gradually given signs of exhaustion in various localities. 

 . . . Wherever the Riparia and Riparia X Rupestris hybrids failed it was 

 always noticed that the exhaustion followed several years of very heavy crops; 

 those vignerons who managed, by a skilful pruning, to keep the vines from yield- 

 ing so heavily, have these vines still in bearing." 



