560 



FUNDAMENTALS OF FRUIT PRODUCTION 



on three stocks; Clevener, a Labrusca-Riparia hybrid, grown in New 

 York as a direct producing wine grape, Rupestris St. George (or du Lot), a 

 stock obtained through Cahfornia from France and Riparia Gloire, also 

 a repatriated American. It should be borne in mind that all the cion 

 varieties are commonly grown in this section as direct producers, i.e., 

 on their own roots. In almost every case at least one of the stocks used 

 caused a marked increase in vigor over that of the cion variety on its 

 own roots. Table 1, condensed from Hedrick's data, shows the growth 

 ratings of several varieties as direct producers and on the various stocks. 

 This growth rating should be distinguished from total growth since 

 Hedrick states distinctly that the grafted made less wood growth than 

 the ungrafted vines. 



Table 1. — Relative Growth Rating of Grape Varieties on Different Stocks 



IN 1910 



(After Hedrick-'^) 



Variety 



Own roots St. George 



Gloire 



Clevener 



Brighton 



Campbell , 



Catawba 



Concord 



Delaware 



Herbert 



lona 



Niagara , 



Vergennes 



Worden 



Average 20 varieties 



55.0 

 17.3 

 40.0 

 46.0 

 46.0 

 64.6 

 26.8 

 53.9 

 44.1 

 26.1 



40.0 



56.0 

 62.1 

 74.0 

 94.0 

 60.0 

 87.5 

 45.6 

 84.5 

 77.8 

 36.0 



63.2 



73.7 

 54.6 

 70.0 

 90.7 

 68.7 

 87.1 

 43.0 

 57.5 

 69.2 

 61.6 



65.2 



75.0 

 35.0 

 81.6 



81.6 



56.4 

 90.3 

 38.1 



67.9 



In general, when a symbiotic relation between stock and cion exists at 

 all, there is apparently a tendency toward a balance between the two. 

 The influence is relative. A dwarfing stock is dwarfing because of the 

 limitations on its development relative to the top. There is nothing 

 inherent which impels it to dwarf all tops worked on it. As an example 

 the quince may be considered. It obviously dwarfs pears in general, 

 yet it is said to increase the vigor of Cratcegus glabra Thunb.^^* while its 

 dwarfing effect on the loquat is slight or absent. ^^ 



Form. — Closely related to vigor of growth, possibly interwoven with 

 it, is form or habit of growth. According to Loudon, ^°^ "Cerasus canaden- 

 sis," naturally a rambling shrub, assumes an upright habit when grafted 

 on the common plum, while Tecoma radica7is on catalpa forms a round 

 head with pendent branches. Garry a elliptica, Sahut states, '^° grafted 

 on Aucuha branches less. Chamcecyparis obtusa pygmcea, according to 



