PLUM (AS. plume, plyme, OHG. pflumo, pfrii ma, Ger. Pfluainr, from Lat. prunum, plum, pruna. plum-tree. from Gk. rpofivov, prounon, rpoDiAvov, pro innon, plum, rpotirn, proune; rpoliavn, proumm', plum-tree). Small trees or shrubs be longing, to the genus Primus, and extensively cultivated as orchard fruits in temperate regions. The fruit is distinguished from the peach. its near relative. by its smooth skin and unwrinkled stone. It is larger than the cherry and is further distinguished from it by the bloom covering it. There are three main groups of widely cultivated plums: (1) Domestiea or European plum (Prunus domestica); (2) .Tapanese plum (Pru nus trifoliata); and (3) native American plums, cultivated only in America, having been derived largely by selection during the closing years of the nineteenth century from numerous native species, the most important of which are: Americana types, from l'runus Americana. com monly found from the Atlantic west to the Rocky Mountains and south to the Gulf: the Wild Goose or Hortulana types, from Prunus hortzdana and Chiekasaw types. from Prunus angustifolia. The domestiea varieties were the first plums cultivated in the 'United States. They thrive in the regions north of Pennsylvania and west to the Great Lakes and on the Pacific Slope, where the American prune industry has reached its greatest develop ment. The European plum (Prunus domestica) is native to Eastern Europe and \Vest-Central Asia. Another plum native to Southern Europe and extensively grown as a stock is the myro bolan or cherry plum (Prunus ecrusifera). There are but very few cultivated varieties of this species. The Japanese plums are native to China. They stand next in commercial impor tance to the European plums. Many varieties ripen much earlier than the European plums.
The fruit is very firm and stands shipment well, and the trees are not so susceptible to black knot and the curculio. They were first intro duced in America about 1870, and have rapidly become popular in the United States, where they can be grown much farther south than the Euro pean plums. There are many varieties of most
of the above species of plums now in cultivation, and in addition a large number of named hybrids.
Plums true to variety are propagated usually by budding the seedlings in August or September. Whip grafting is used to some extent and has proved especially valuable in working plums on peach roots. They may also be top-worked in the same manner as apples. Plums. as a rule, do best in a deep, rather heavy soil with an open subsoil. The domesticas prefer a heavy clay soil, while the Japanese varieties and some of the hybrids may be grown on light sandy soils. Most varieties may he set in the orchard when one year from the bud or graft. but with the Euro pean plums two-year-old trees are preferred. Waugh and other investigators have shown that for all practical purposes native American plums and Japanese varieties are sterile to their own pollen and will not produce fruit unless the trees are mixed in the orchard with other varieties. Plums are set in the about 15 feet apart each way. A few varieties require 20 feet eneb way. Pruning the plum is confined largely to the formation of the head during the first two or three years' growth in the orchard, and after wards to removing dead and crossed branches. The plum orchard in America is usually plowed in early spring and kept well cultivated until the middle of summer, when it is seeded to some CONTI' crop. In some of the Northwestern States mulching with straw. marsh hay. etc.. has been found preferable to cultivation. A moderate amount of barnyard manure applied every second year has been found beneficial in the plum or chard, and wood ashes on soils deficient in potash and lime. .lost Narieties (:f plums told regularly to roerbear. and thinning has been found neces sary to ,(-cure the fruit. especially with the Allierleall Nariet les. The plums are left to stand IWO Or inches ;Tart. 'They are keted :1.? Soon as tiny become well colored. In the 'muted States the eight-pound grape basket makcs one of the most satisfactory packages.