Agriculture of Maine 5: 112-113 (1906)
Plant Breeding in its Relation to American Pomology (extract)
W. M. Munson
BREEDING FROM ASEXUAL PARTS
The distinction between seedling varieties and bud varieties is one of degree rather than of kind. The different buds on a tree frequently produce offspring possessing quite as distinct individuality as do the different seedlings from the same tree. So the tree should be considered not as an individual but rather as a collection of individuals, the bud being the unit. Now no two buds on a given tree are subjected to precisely the same conditions. All of the buds cannot possibly survive, hence arises a constant and intense struggle for existence. Owing to the different conditions of light, air, food, and room for extension, some branches will be large and vigorous, others will be small and weak; some will produce fruit freely, others will be barren. In the same way, no two fruits are ever exactly alike. Some will be large, others small; some roundish, some oblong; some highly colored and of good flavor; others pale and insipid.
|* American Garden. 1898, p. 466.
Gardeners' Chronicle. 1899
This fact of the universality of bud varieties, together with the fact that variations may be perpetuated by asexual means is of the utmost importance in practical horticulture and in the systematic improvement of fruits and vegetables. The practical fruit grower knows that some trees never bear any fruit and that others of the same kind bear abundantly; that some Baldwins and Spys are habitually large, and others habitually small and unsatisfactory, and these observations are borne out by the records of the Station orchard. Upon close examination of the branches of an individual tree, through a series of years, the same phenomena would be found to exist in individual branches. A very good illustration of the case in point is that of a currant plantation cited by Powell.* A plantation of Fay currants containing some 12,000 bushes came directly or indirectly, through cuttings, from 25 selected plants, purchased when the variety was first introduced. The original plants were uniform in size and very productive. In the haste for a large number of plants the new wood was cut from these bushes every fall, and when more bushes were established they in turn were divided into cuttings as often as new wood was made. Little attention was paid to the bearing capacity of the bushes in later generations because of the excellent character of the original stock. As a result of this lack of attention, at the end of 12 years some of the bushes were found to be heavy bearers, others very light bearers and others almost barren. How this came about is readily seen, and the remedy is equally obvious. If a single bud produces a branch which is barren, or nearly so, and that branch happens to be taken as a cutting, naturally a barren bush results. If this bush, before its character is determined, is used for cuttings, the tendency is perpetuated and an ever increasing series of worthless plants is established.
Some of the numerous examples of bud variations in apples, pears and other fruits will suggest themselves. In Virginia, Albermarle Pippin is a familiar example of bud variation from the Yellow Newtown. In Canada the Red Gravenstein appears. In the Northwestern states, King is hardly recognized because of its elongated form. The propagator has only to form a clear idea of the type of Baldwin, Newtown, King, or other fruit which he wishes to attain, then to select from each generation buds from branches which appear most nearly approximating his ideal. If then the differences in the buds of a tree or other fruit plant can be perpetuated by asexual means, as by cutting, grafting, etc., it is evident that this method can be depended upon for the systematic improvement of existing varieties; and with most of the commonly cultivated fruits such improvement is vastly more important than a wholesale production of new forms.