Malus(redirected from Crab-apple)
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(apple), a genus of deciduous trees and shrubs of the family Rosaceae. There are two types of branches: the short branches bear the flower buds and fruit, and the long ones are for growth. Wild species have thorny branches. The petiolate leaves are bare or tomentose, with deciduous or persistent stipules. The white, pink, or red flowers are in a dichasium or corymb. The fruit, which is usually edible, is a pome (commonly known as an apple). The pome has five two-seeded cells.
There are 36 apple species (according to other data, about 150). Fifteen species occur in the USSR. Of the ten to 12 cultivated species, the most common are M. domestica, M. prunifolia, and M. pumila. M. domestica includes most of the world’s cultivated apple varieties; the species sometimes escapes cultivation.
Common wild species include M. sylvestris (crab apple), which grows in the European USSR and the Caucasus; M. orientalis, which occurs in Middle Asia, Iran, the Crimea, and the Caucasus; M. baccata (Siberian crab), which is found in China; Mongolia, Primor’e Krai, and Eastern Siberia; M. niedzwetzkyana, which grows in the forests of the Tien-Shan; and M. soulardii (Soulard crab), which occurs in North America along the Mississippi Valley.
Wild apple species occupy extensive areas in the European USSR (Voronezh and Kursk oblasts, RSFSR), the Crimea, the Caucasus, Middle Asia, and Siberia.
M. domestica can reach a height of 14 m but is usually 3–6 m tall. The trunk, which in old trees may reach as much as 90 cm in diameter, is covered with cracked bark. The crown is most frequently broad and spreading; occasionally it is globose, oval, or somewhat drooping. Pruning is common. In northern regions apple trees are cultivated in prostrate form (see PROSTRATE CULTIVATION OF FRUIT TREES). The oval leaves, which are 5–10 cm long, have sharp tips and are crenate-serrate. Sometimes the leaves are rugate and tomentose. The large white or pink flowers are on short, white, tomentose pedicels. The fruits vary in size (diameters are greater than 3 cm), shape, and color. The root system is deep and extensive, extending outward two or three times farther than the crown.
M. domestica has a life-span of as much as 100 years. Wild varieties may reach 300 years of age. Fruiting usually begins in the fourth to 12th year depending on the variety and cultivation conditions. The plant is productive from 40 to 50 years. The fruit is borne on the ends of the shortened branches. Flowering occurs early—in April or May—and lasts eight to 12 days. There is cross-pollination. With abundant flowering, about 30 percent of the set fruits mature fully, and the remainder are shed (unfertilized set fruits and, in June, unripe apples).
Apple trees are winter-hardy and cold-resistant plants. Germination can occur on a variety of soils. Certain unfavorable conditions, for example, a shortage of moisture or minerals, result in the shedding of a considerable number of set fruits.
The apple is among the major fruit crops. Apples contain an average of 84–90 percent water, 5–15 percent sugars (predominantly fructose), 0.37 percent malic acid, 0.11 percent citric acid, 1.2 percent pectin, and as much as 0.27 percent tannic acid. There is considerable vitamin C content. Apples are eaten in fresh or cooked form. They are also processed into preserves, jam, marmalade, pastilles, juice, wine, and other products. Apples may also be dried or soaked. The fruits of wild varieties are usually used for processing. Many species (M. baccata, M. niedzwetzkyana) are raised as ornamentals in parks and gardens and are used in forest development for field protection. All species yield a substantial amount of nectar. The solid, strong wood is easy to cut and polish; it can be used in furniture-making and the production of small articles.
The apple tree has been cultivated for a long time. It is raised in countries with temperate and subtropical climates, as well as in the mountainous regions of the tropics. About 10,000 varieties have been developed. World production of apples was 18.2 million tons in 1961–65, 21.9 million tons in 1970, and 21.5 million tons in 1977 (including 3.05 million in the USA, 2.19 million in France, and 1.8 million in Italy). In 1977 the yield of apples and pears in the USSR was 7.53 million tons, with an average productivity of 42.2 quintals per hectare. The main apple-growing regions in the USSR are the Northern Caucasus, the Ukraine, Moldavia, Transcaucasia, Southern Kazakhstan, and Middle Asia. Apples are grown in the Central Chernozem and Nonchernozem zones, as well as in Siberia and the Altai. About 350 varieties were regionalized in 1978. Late-winter varieties, including Simi-renko, Reinette, English winter gold Pearmain, Calville blanche, Bile rozmarinove, and Oporto, are most common in the southern regions. Early-winter and fall varieties, for example, Antonovka obyknovennaia, Streifling, Borovinka, Melba, Korichnoe polosatoe, and Pepin shafrannyi, are cultivated in the central regions of the European USSR and in the Baltic states.
Malus is propagated by grafting. The seedlings of local varieties and forms (Antonovka, Borovinka, reinettes), as well as M. sylvestris and M. prunifolia, are used as stock. Dwarf stock also includes M. pumila and its Dusen and Paradizka varieties. Seed propagation is used in breeding. The best time to plant two-year old seedlings in the southern regions is the fall, in the central belt the fall or early spring, and in the northern regions the spring. On fertile soil, plants on rapidly growing stock are placed 3–5 m apart, with an interrow of 6–8 m. (For dwarf stock the respective figures are 1.5–3 m and 4 m.) For the first ten to 12 years after planting, the interrows of apple orchards are used to grow other crops, including vegetables. The area around the trunk is either cultivated or mulched. In a fruit-bearing orchard the soil is maintained as bare fallow, fluctuating with short-term flooding or a green manure. Fertilizing and irrigation norms vary according to zone. Pruning and shaping are determined by the age and special features of the variety (seePRUNING FRUIT AND BERRY PLANTS; TRAINING; and TOPIARY WORK).
Pests of apple trees include the codling moth, the apple blossom weevil, apple aphids, and the apple moth (Yyponomeuta malinellus). Diseases include scab, fruit rot, and black rot.
REFERENCESLikhonos, F. D. Iablonia. Moscow-Leningrad, 1955.
Simirenko, L. P. Pomologiia, vol. 1: Iablonia. Kiev, 1961.
Budagovskii, V. I. Promyshlennaia kul’tura karlikovykh plodovykh derev’ev. Moscow, 1963.
Ul’ianishchev, M. M. Iablonia, 2nd ed. Moscow, 1968.
Kolesnikov, V. A. Chastnoe plodovodstvo. Moscow, 1973.
M. T. TARASENKO