572 FUNDAMENTALS OF FRUIT PRODUCTION 



been noted only in rich valley soil of the coast counties and only with 

 certain varieties. A similar condition has often been noted in Europe, 

 but it is usually easily overcome by longer pruning and diminishes with 

 age. " 



Husmann^^ shows very striking differences in the product of the 

 Panariti or currant grape on various stocks in California, as shown in 

 Table 4. 



Rolfs^-^ suggests a difference in the value of different stocks for the 

 mango. The kumquat on sour orange roots grows a vigorous tree but 

 it is practically barren. 



Fruit Setting. — A casual survey of European literature shows a con- 

 siderable body of opinion to the effect that the setting of fruit is influenced 

 sometimes by the stock on which the fruiting wood is worked. Par- 

 ticularly does this appear in grapes. Ravaz is quoted to the effect that in 

 sandy soils strong growing stocks fail to set fruit and for this reason many 

 of the Riparia and Rupestris hybrids are not well suited to such soils. ^*^ 

 Baco^ found the short and reflexed stamens characteristic of many hybrid 

 stocks, but very rare in the pure Vinifera, produced in Baroque grafted on 

 1202. These characters have been shown in the section on Fruit Setting 

 to be associated with lack of viability in the pollen. Though it is not 

 clear from Baco's account whether this condition was universal on this 

 stock, he recorded it on other stocks also, including the Rupestris du Lot 

 (St. George). Consequent upon this condition was a considerable 

 amount of couture and of miller andage. Nevertheless, he recorded a 

 general increase in production on these same stocks.*^ 



Rupestris du Lot stock is reported to cause poor setting of fruit in 

 many Victorian vineyards ;^^ the vigorous growth of this same stock 

 produces coulure in some varieties in California. ^^^ Odart, writing before 

 the days of phylloxera in Europe, stated that the Raisin des Dames set 

 fruit much better when grafted on the common white Muscat;''^ Bur- 

 bidge^^ cites similar cases from the experience of forcing house grape 

 growers. Baltet'^ states that the Cabernet grape when grafted is exempt 

 from coulure beside own-rooted plants that are badly affected and quotes 

 Hardy: "Graft the Chasselas Gros-Coulard, even on itself, and you will be 

 resisting coulure." In Australia when the Kieffer pear is grown on wet 

 soils better setting occurs if quince roots are used."*^ Sahut'^" states that 

 Chionanthus virginica, grafted on ash, flowers abundantly but never 

 fruits, while as a seedling it bears. 



Size of Fruit. — So many factors affect the size of fruit that it is difficult 

 to find clear evidence of any considerable influence on size that can be 

 attributed to the stock. Sometimes grape growers imagine an increase 

 in the size of the individual berries when certain stocks are used. Bur- 

 bidge,'^ for example, cited an instance in which the Gross Guillaume grape 

 was considered to form larger berries on Muscat of Alexandria than 



