CLONAL ROOTSTOCKS FOR THE APPLE 5 



probably JMalling VIII, but we have seen none In recent years. This corresponds 

 to the situation found by Hatton. Evidently the early importations of dwarf 

 apple stocks were mixtures of different types, which may account in part for the 

 poor results from dwarf trees reported by early American investigators. 



Propagating Clonal Rootstocks 



As clonal rootstocks cannot be reproduced from seeds, it is necessary to resort 

 to asexual methods of propagation. We might expect that the convenient means 

 would be b}' cuttings. Most of them grow quite readily from root cuttings and 

 some grow sparingly from stem cuttings. No method of handling stem cuttings 

 so as to get a stand sufficient to make the method practical is known to the writer. 

 Material for root cuttings is not often available in quantity. When one digs 

 nursery trees propagated on a known clonal rootstock, he may be able to recover 

 roots for a considerable number of cuttings. The value of a nurser^^ tree depends 

 more on the number of roots than on their length; consequently 'long roots may 

 be shortened and the pieces used as root cuttings. The roots must be not over 

 two years old and should be 3/16 inch or more in diameter and 3 to 5 inches long. 

 The cuttings are lined out in nursery rows in a slanting position with the top end 

 of the root at the surface of the soil. Under good growing conditions, they may 

 be farge enough to bud the first summer or they may be held over until the second 

 season and then budded. 



Clonal rootstocks may also be reproduced by nurse-root grafts. ' Scions of 

 one-year wood from the desired clon are whip grafted on short, straight seedling 

 roots and planted like ordinary root grafts. The top of the scion should be at 

 the surface of the ground. When the new growth is 4-6 inches tall, moist soil 

 is hilled up around it to favor rooting. Most clonal rootstocks thus handled will 

 produce roots in practically every case the first season. When the grafts are 

 dug in the fall or spring following planting, the seedling root piece is cut off and 

 the rooted scion lined-out for budding. 



These methods of propagation are rather slow and cumbersome. The usual 

 and best way to produce clonal rootstocks is by stooling or by layering. A stool 

 or layer bed should be established only on strong soils. A fertile sandy loam is 

 perhaps best, but doubtless a -considerable range of soils may be found suitable. 

 The soil must be well drained so that there will- be no heaving of the roots from 

 winter freezing nor a high water table during the growing season; yet it must 

 not have excessive drainage so that the plants suffer during dry periods. If well- 

 rotted stable manure is available, a heavy coating may be plowed in before the 

 plants are set unless the soil is already in a high state of fertility. Either too low 

 or too high fertility is undesirable. Incorporation of peat moss or similar organic 

 matter improves the physical condition, especially of heavy soils, and favors 

 cultural operations as well as the growth of the plants. 



The Mailing apple rootstocks may be reproduced satisfactorily bj' stooling, 

 also called mound layering. Vigorous well-rooted plants should be used. If the 

 plants are not very vigorous and well rooted, they may be lined-out and grown 

 for a year or two before setting in the stool bed. It is well to have a supply of 

 such plants on hand to replace plants that fail in the permanent bed. 



The plants are set about 18 inches apart in furrows 5 to 6 feet apart. They are 

 set in furrows to keep the. crowns of the plants low and the rather wide space 

 between the rows is to make plenty of soil available for hilling up the shoots as 

 described later. Much depends on a vigorous growth the first year as it is neces- 

 sary to have a root system at least equal to that of a one-year tree if a good yield 



