BULLETi:^ Wo. 190. 



DEPARTMENT OF HORTICULTURE. 



THE PROPAGATION OF APPLE TREES ON 

 THEIR OWN ROOTS. 



BY J. K. SHAW. 



INTRODUCTION. 



The methods of propagation of tree fruits in common use among 

 nurserymen produce trees the trunk and crown of which are of the variety 

 desired, whUe a part or the whole of the root system is of seedhng origin. 

 In many cases roots are thrown out from the base of the scion that are, 

 of course, of the variety of the aerial part of the tree, but it is doubtless 

 true that in most cases, especially with budded trees, the seedling forms 

 the greater part, if not the whole, of the root system. This means that 

 in any orchard of any one variety there is a gi'eat deal of variation in the 

 root systems. No two are of identical constitution. This is due to the 

 complexity of the genetic constitution of our cultivated varieties of 

 apples. Seedlings of a single variety, even if from self -fertilized seed, 

 show great variation and many different combinations of characters. 



It is reasonable to suppose that these differing seedling roots should 

 cause more or less modification of the top, and there is abundant evidence 

 that this is the case. The most common example is found in dwarf trees. 

 There are many types of the common apple that, when used as stocks, 

 inhibit the growth of the scion, and those that will throw out roots from 

 the stem readily are used as dwarfing stocks. It is well known that dwarf 

 stocks influence also the size, color, quality and season of maturity of the 

 fruit. It is therefore reasonable to believe that many of the individual 

 differences among the trees in an orchard may be due to the varying 

 seedling root systems, and such individual differences, especially in pro- 

 ductiveness, are greater than is generally reahzed. If trees could be 

 propagated on their own roots, or on the roots of a clonal variety known 

 to be well suited to the scion variety, much might be gained in uniformity 

 and fruitfulness in the orchard. 



