I 



RESISTANT VINES. 5 



(b) Resistant Stocks. Though high resistance to phylloxera is essential 

 in a grafting stock, there are other characteristics equally necessary. 

 The Rotundifolia (Scuppernong), which has the highest resistance of any 

 vine, is useless as a stock on account of the impossibility of grafting it with 

 any Vinifera variety. This is due to a lack of affinity, which means a 

 lack of similarity in structure and composition between the tissues of the 

 stock and those of the scion. This lack, in extreme cases, results in an 

 imperfect and temporary union, but when not excessive, only in a slight 

 decrease of vigor. The affinity is not perfect between Vinifera varieties 

 and any resistant stock, but in the case of Riparia and Rupestris is 

 generally sufficient to insure permanence to the union, and the slight 

 decrease of vigor consequent often results in an increase of fruitfulness. 

 It is for this reason that certain varieties when grafted on resistant stocks, 

 especially on Riparia, often bear larger crops than when grown on their 

 own roots. Not all varieties of Vinifera have the same affinity for the 

 same stock. For this reason it is desirable to be cautious about making 

 new or untried grafting combinations on a large scale. Some varieties, 

 such as Carignan, Petite Sirah, Clairette, and Cabernet Sauvignon, do 

 excellently on all stocks; while others, such as Mondeuse and Gam ay, 

 do not make a very good union with any of the thoroughly resistant 

 stocks. The Petit Bouschet and Cinsaut make very poor unions with 

 any variety of Riparia, but do fairly well on Rupestris St. George. The 

 Pinot Noir makes a vigorous growth upon Rupestris St. George, but 

 bears much more prolifically upon Riparia Gloire. 



Selection. A very serious defect of many resistant stocks is a slender 

 habit of growth. This is true of most of the vines found growing wild, 

 and cuttings from such vines make poor grafting stock for the stout 

 Vinifera varieties, which will produce a trunk four inches in diameter 

 while the stock is growing only two inches. This is particularly true 

 of the wild Riparias. For this reason great care has been exercised in 

 selecting the stronger-growing forms, and at present we have selected 

 Riparia varieties which almost equal Vinifera in the stoutness of their 

 trunks. The best of these are the Riparia Gloire de Montpellier and 

 the Riparia Grande Glabre, the first of which has given the best results 

 in California. 



RESISTANT VINES AND THEIR HYBRIDS. 



BY E. H. TWIGHT. 



If we study the conditions affecting the adaptation of resistant vines, 

 we see that the amount of lime contained in the soil, the degree of com- 

 pactness, the moisture, and the fertility of the land are the most 

 important factors. The proportion of lime in the soil has been, in 

 many countries and particularly in France, the greatest drawback in 



