THE ROOT SYSTEMS OF FRUIT PLANTS 591 



diminution in vigor. The process, therefore, apparently is not per se 

 devitalizing. It has, moreover, certain marked advantages, one of 

 which is uniformity of the roots. 



This uniformity in the roots frequently is of considerable importance. 

 The constant tendency to variation in seedlings is not confined to quality, 

 color and size of the fruit but extends to every character of the plant. 

 They may vary in vigor of growth as much as in the color of the fruit; 

 the (juality of fruit varies no more than the stature; the depth of rooting, 

 resistance to cold, to drought, to moisture, to alkali, all are variable 

 characteristics. Hatton^'' states: "Free stock is a comprehensive term, 

 meaning no more than seedlings which include dwarf stocks both fibrous 

 and stump-rooted, as well as vigorous ones resulting from a well-balanced 

 root system." The seedling root, then, is in a measure an unknown 

 quantity. The tree planted in the orchard is standardized above ground, 

 uncertain below ground. The stock for any individual tree may be more 

 vigorous or more hardy or more resistant than the average; it is just as 

 likely to be less so. In France the prospective grape grower whose soil is 

 strong in lime knows that certain stocks do not thrive on those soils ; he is 

 able to pick a lime-enduring stock, for grape root stocks have been stand- 

 ardized through growth from cuttings. If, however, he has a rocky, 

 thin soil in a hot, dry exposure, he can select another stock, known to be 

 the best for such locations. Were he to rely on seedlings he would be 

 indulging in a lottery whose results could be told only after a year or more. 

 To replace those which failed he would use more unknown quantities. 



Grapes in Particular. — Varietal differences in the character of root 

 systems produced from cuttings are recognized in grapes. Bioletti and 

 dal Piaz" explain the susceptibility of Riparia and the immunity of 

 Rupestris stocks to drought by the shallow roots of the former and 

 the deeply penetrating roots of the latter. In poorly drained soils and 

 in soils with the water table high for any length of time, these same 

 peculiarities tend to reverse the order of suitability. Hedrick sug- 

 gests that the small amount of winter killing of grapes on Rupestris 

 St. George stock as compared with that on other stocks in an experimental 

 vineyard in New York may have been due to its deep rooting habit.''* 

 The advantage of having stocks of known performance is obvious. 



Apples and Pears in Particular. — Fortunately apple and pear stocks 

 are fairly adaptable. They seem so, certainly— perhaps because there 

 is no standard with which to compare them. However, every careful 

 grower recognizes that some of his trees consistently bear more or less 

 than others. This raggedness may be attributed to minor variations 

 in soil and doubtless correctly so in many cases; it is sometimes attributed 

 to bud variation, though the work of Crandall^^ and of Gardner*^^ suggests 

 the doubtful importance of this source of variation. The unevenness 

 in a seedling orchard strongly suggests that were the tops all removed 



