USDA Yearbook (1937)

Some Unusual Opportunities in Plant Breeding

GEORGE M. DARROW, Senior Pomologist,
GUY E. YERKES, Horticulturist, Division of Fruit and
Vegetable Crops and Diseases, Bureau of Plant Industry

CHINESE AND OTHER BUSH CHERRIES

6 DARROW, G. M. THE CHINESE BUSH CHERRY
Jour. Heredity 15: 169-170, illus.1924.
Figure 8.—Flowers of the Chinese bush cherry. It flowers on the previous season's growth.
Figure 9.—The Chinese bush cherry in fruit. Its brilliant red fruits range in flavor from the sweet to the sour cherries. They are produced in great abundance provided they escape spring frosts and brown rot. Objectives in breeding this fruit should include late-flowering, brown rot-resistant seedlings.
Figure 10.—Seedling plants of the Chinese bush cherry; in the middle an early flowering, at the right a later flowering, and at the left a much later flowering sort. These seedlings illustrate the possibility of obtaining much later flowering selections that may escape unseasonable frosts.

THE Chinese bush, Manchu, or Nanking cherry, Prunus tomentosa Thunb. (called by the Chinese the mountain cherry),6 has been grown in the United States some 50 years as an ornamental shrub but now is attracting attention for its fruit. It is one of the earliest of all shrubs to flower in the spring, its white to pink blossoms (fig. 8) opening just as the leaves start to unfold and its brilliant red fruit (fig. 9) ripening with the last of the strawberries. The fruit has a range in flavor and texture from the sweet to the sour cherry with a peculiarly attractive tang. It is as large as the wild cherries of Europe, from which the cultivated sweet and sour cherries have originated. The foliage is resistant to the common cherry leaf troubles. The tree is cultivated to some extent in China, and the fruit is also gathered in the wild and sold in the markets. The range of the Nanking cherry in Asia is from southern Manchuria to the Kashmir region of northern India, a region for the most part semiarid and in latitude and climate comparable to the territory from eastern New Mexico northward to North Dakota.

When they escape spring frosts and severe attacks of brown rot, the bushes are loaded with fruit of the size of small sour cherries. The most needed improvements are the introduction or discovery of late-flowering and brown-rot-resistant seedlings (fig. 10). The brown rot fungus often kills back twigs and branches in humid sections.

7 SLATE, G. L. THE IMPROVEMENT OF PRUNUS TOMENTOSA.
Amer. Soc. Hort. Sci. Proc. (1929) 26: 28-31. 1930.

Harlow Rockhill, strawberry breeder at Conrad, Iowa, has crossed the Nanking cherry with the western sand cherry, Prunus besseyi Bailey, and has grown several generations of hybrid seedlings. He feels that some are very promising for Iowa conditions, as they flower later and are less often injured by cold than the Nanking cherry. Importations are needed from different regions to make selections adapted for the coldest to the warmest, and the driest to the most humid regions of this country. Rockhill has crossed the Nanking cherry with the Napoleon (Royal Anne), Montmorency, and Zumbra cherries, and there is the possibility of obtaining hybrids with many other cherries. The Arnold Arboretum reported having a natural hybrid between P. tomentosa and P. triloba Lindl. in their plantings. Slate,7 of the New York (State) Agricultural Experiment Station, has selected fine fruiting seedlings at Geneva and has started propagating them. By and large, it is a promising fruit for the plant breeder, and it may have commercial possibilities.

Prunus glandulosa Thunb. and P. japonica Thunb. are very hardy dwarf shrubs that are ornamental and have deep red to purple-black fruits useful for pies, jellies, and sauce. There are also many other species of bush cherries in Asia that may be worth using in breeding. Besides the bush cherries, P. triloba, classed as a flowering almond, is possibly a still more beautiful hardy flowering and fruiting shrub with flowers of pure pink.