The cherries of New York

by U. P. Hedrick

The total number of cherries under discussion is 1,145.

To improve the cherry the breeder must know the material with which he is working. The following is a brief discussion of the characters of this fruit to be found in the technical descriptions of species and varieties.

TREE AND FRUIT CHARACTERS OF THE CHERRY

Species of cherries have very characteristic trees. The merest glance at the tree enables one to tell the Sweet Cherry, Prunus avium, from the Sour Cherry, Prunus cerasus. The first named is the larger of the two, especially reaching a greater height, is pyramidal in shape, with branches erect and bearing much less foliage than the Sour Cherry. The Sweet Cherry often lives for a century or more—the Sour Cherry attains but the three score years and ten of man. Prunus cerasus is easily distinguished from Prunus avium by its comparatively low, roundish and never pyramidal head. So, too, many of the varieties of either of these two species are readily told in the orchard by the size or habit of the plant. Other species are either shrubby or tree-like and their varieties may often be identified from the spaciousness or dwarfness of its trees. Size is rather more variable than other gross characters because of the influence of environment—food, moisture, light, isolation, pests and the like—yet size in a plant, or in the parts of a plant, is a very reliable character when proper allowances have been made for environment.

Habit of growth, unlike size, varies but little with changing conditions and thus becomes a most important means of distinguishing species and varieties and not infrequently sets the seal and sign of desirability for an orchard cherry. More than any other character, habit of growth gives what is called "aspect" to a cherry tree. Thus, a species or a variety may be upright, spreading, round-topped, drooping or weeping in habit of growth; the head may be open or dense and may be formed by a central shaft with several whorls of branches or by three or four trunk-like stems each with its scaffolding branches. The trees may grow rapidly or slowly and may be long-lived or short-lived. The trunks may be short and stocky, or long and slender, straight or crooked, gnarled or smooth, these characters often determining whether a cherry is manageable or unmanageable in the orchard.

The degree of hardiness is a very important diagnostic character for groups of cherries and often wholly indicates their value for agriculture. Thus, the varieties of Prunus avium are but little hardier than the peach while those of Prunus cerasus are as hardy or hardier than the apple. The range of varieties as to hardiness falls within that of the species and it is interesting to note that in Europe, where the wild Prunus avium is very common, in the many centuries since the fruit has been under domestication, a cultivated variety hardier than the wild Sweet Cherry has not been developed. Cherries are designated in the technical descriptions as hardy, half-hardy and tender.

Productiveness, age of bearing, and regularity of bearing are distinctive and valuable characters of orchard cherries but not of wild cherries. The care given the tree greatly influences fruitfulness, yet the quantity of fruit produced is often a helpful means of identifying a variety and is a character that must always be considered by the plant-breeder. Age of bearing and regularity of bearing are most important characters with the pome fruits, the apple, in particular, but while worth considering with the drupes are of relatively little value, all drupaceous fruits coming in bearing at about the same time for the species and all bearing regularly, as a rule, unless interfered with by some outside agency preventing the setting or causing the dropping of fruit.

Immunity and susceptibility to diseases and insects are valuable taxonomic characters of both species and varieties of cultivated cherries. Thus, the varieties of Prunus cerasus are very susceptible to black knot (Plowrightia morbosa), while those of Prunus avium are almost immune. On the other hand, Prunus avium is an inviting prey to San José scale (Aspidiotus perniciosus), while Prunus cerasus is but little injured, indeed, seldom attacked; Prunus mahaleb appears to be almost wholly immune to the powdery mildew (Podosphaera oxyacanthae), while Prunus avium and Prunus cerasus are much attacked, though Wood, a variety of Prunus avium, is almost immune. The English Morello, a variety of Prunus cerasus, is very subject to leaf spot (Cylindrosporium padi), while Montmorency, of the same species, is nearly immune. These examples can be multiplied many times by references to the discussions of varieties, and represent only observations on the grounds and in the neighborhood of this Station. They serve to show the great importance, to the fruit-grower, the plant-breeder and the systematist, of natural resistance to disease and insects.

Both the outer and the inner bark have considerable value in determining species but are of little importance in identifying varieties and have no economic value to the fruit-grower and hence but little to the breeder. Smoothness, color, thickness and manner of exfoliation are the attributes of the outer bark to be noted, while the color of the inner bark is the only determinant and that relatively unimportant. In young trees the bark of the cherry of all species is smooth, glossy or even brilliant; but later it becomes uneven, scaly and dull, usually ash-gray but varying in all of these characters to an extent well worth noting for taxonomic purposes. Cherries, in common with most trees, have a lighter colored bark in cold than in warm regions, and in dry than in wet areas.

Branches and branchlets are very characteristic in both species and varieties. The length, thickness, direction, rigidity and the branching angle are valuable determining characters and very stable ones, changing but little even with marked variations of soil and climate. Thus, a Sweet Cherry tree can be told from a tree of the Sour Cherry, or the English Morello can be distinguished from Montmorency by branch characters as far as the outlines of the trees are discernible. Few cherries bear spines but all are more or less spurred and these spurs are quite characteristic even in varieties. With the branchlets the length of the internodes should be considered and their direction, whether straight or zigzag; also color, smoothness, amount of pubescence, size and appearance of the lenticels, the presence of excrescences, are all to be noted in careful study though all are more or less variable, pubescence especially so, this character being too often relied upon in descriptions by European botanists and pomologists.