solution of Bordeaux mixture or with ammoniacal solution
of carbonate of copper is recommended. The sooty mould of
orange, which forms a black incrustation on the leaves and also
the fruit, probably occurs wherever the orange is cultivated.
It is caused by species of Meliola; in Europe and the United
States, by M. Penzigii and M. Camelliae. The fruit is often
rendered unsaleable and the plant is also injured as the leaves
are unable properly to perform their functions. The fungus is not
a parasite, but lives apparently upon the honey-dew secreted
by aphides, &c., and is therefore dependent on the presence
of these insects. Spraying with resin-wash is an effective
preventive, as it destroys the insects. Several insect enemies
attack the plant, of which the scale insect Aspidiotus is the most
injurious in Europe and the Azores. In Florida another species,
Mytilaspis citricola (purple scale), sometimes disfigures the
fruit to such an extent as to make it unfit for market. Several
species of Aleyrodes are insect pests on leaves of the orange;
A. citri, the white fly of Florida, is described as the most important
of all the insect pests of the crop in Florida at the
present time, and another species, A. Howardi, is a very serious
pest in Cuba. Cold weather in winter has sometimes proved
destructive in Provence, and many plantations were destroyed
by the hard frosts of 1789 and 1820.
Besides the widespread use of the fruit as an agreeable and wholesome article of diet, that of the sweet orange, abounding in citric acid, possesses in a high degree the antiscorbutic properties that render the lemon and lime so valuable in medicine; and the free consumption of this fruit in the large towns of England during the winter months has doubtless a very beneficial effect on the health of the people. The juice is sometimes employed as a cooling drink in fevers, as well as for making a pleasant beverage in hot weather.
The bitter orange is chiefly cultivated for the aromatic and tonic qualities of the rind, which render it a valuable stomachic. Planted long ago in Andalusia by the Moorish conquerors, it is still extensively grown in southern Spain—deriving its common English name of “Seville” orange from the abundant groves that still exist around that city, though the plant is now largely cultivated elsewhere. The fruit is imported into Great Britain and the United States in considerable quantities for the manufacture of orange marmalade, which is prepared from the pulp and rind, usually more or less mingled with the pulp of the China orange. In medicine the fresh peel is largely employed as an aromatic tonic, and often, in tincture and syrup and “orange wine,” as a mere vehicle to disguise the flavour of more nauseous remedies. The chief constituents are three glucosides, hesperidin, isohesperidin and aurantiamarin, the latter being the bitter principle; and an oil which mainly consists of a terpene known as limonene. The essential oil of the rind is collected for the use of the perfumer, being obtained either by the pressure of the fresh peel against a piece of sponge, or by the process known as écuelle, in which the skin of the ripe fruit is scraped against a series of points or ridges arranged upon the surface of a peculiarly-shaped dish or broad funnel, when the oil flows freely from the broken cells. Another fragrant oil, called in France essence de petit grain, is procured by the distillation of the leaves, from which also an aromatic water is prepared. The flowers of both sweet and bitter orange yield, when distilled with water, the “oil of Neroli” of the druggist and perfumer, and likewise the fragrant liquid known as “orange-flower water,” which is a saturated solution of the volatile oil of the fresh flowers. The candied peel is much in request by cook and confectioner; the favourite liqueur sold as “curaçoa” derives its aromatic flavour from the rind of the bigarade. The minute immature oranges that drop from the trees are manufactured into “issue-peas”; from those of the sweet orange in a fresh state a sweetmeat is sometimes prepared in France. Orange trees occasionally acquire a considerable diameter; the trunk of one near Nice, still standing in 1789, was so large that two men could scarcely embrace it; the tree was killed by the intense cold of the winter of that year. The wood of the orange is of a fine yellow tint, and, being hard and close-grained, is valued by the turner and cabinetmaker for the manufacture of small articles; it takes a good polish.
Although the bitter “Poma de Orenge” were brought in small quantities from Spain to England as early as the year 1290, no attempt appears to have been made to cultivate the tree in Britain until about 1595, when some plants were introduced by the Carews of Beddington in Surrey, and placed in their garden, where, trained against a wall, and sheltered in winter, they remained until destroyed by the great frost of 1739–1740. In the 18th century the tree became a favourite object of conservatory growth; in the open air, planted against a wall, and covered with mats in winter, it has often stood the cold of many seasons in the southern counties, in such situations the trees occasionally bearing abundant fruit. The trees are usually imported from Italy, where, especially near Nervi, such plants are raised in great numbers for exportation; they are generally budded on the stocks of some free-growing variety, often on the lemon or citron.
The orange has been usually cultivated in England for the beauty of the plant and the fragrance of its blossoms, rather than for the purpose of affording a supply of edible fruit. The latter can, however, be easily grown in a hot-house, some of the fruits thus grown, especially those of the pretty little Tangerine variety, being superior in quality to the imported fruit. The best form of orange house is the span-roofed, with glass on both sides, the height and other conditions being similar to those recommended for stove plants. The trees may be planted out, a row on each side a central path, in a house of moderate width. They will flourish in a compost of good, light, turfy loam and well-decayed leaf-mould in equal proportions, to which a little broken charcoal may be added. Each year the trees should be top-dressed with a similar compost, removing some of the old soil beforehand. The trees, if intended to be permanent, should be placed 10 to 12 ft. apart. It will often be found more convenient to grow the plants in pots or tubs, and then bottom heat can be secured by placing them on or over a series of hot-water pipes kept near to or above the ground level. The pots or tubs should be thoroughly well drained, and should not be too large for the plants; and repotting should take place about every third year, the soil being top-dressed in intervening years. The temperature may be kept at about 50° or 55° in winter, under which treatment the trees will come into bloom in February; the heat must then be increased to 60° or 65° in the day time, and later on to 80° or 85°. Throughout the growing season the trees should be liberally watered, and thoroughly syringed every day; this will materially assist in keeping down insects. When the trees are in bloom, however, they must not be syringed, but the house must be kept moist by throwing water on the pathways a few times during the day. When the flowers have fallen the syringe may be used again daily in the early morning and late afternoon. The fruit may be expected to ripen from about the middle of October to January, and if the sorts are good will be of excellent quality. When the trees are at rest the soil must not be kept too wet, since this will produce a sickly condition, through the loss of the small feeding roots. The trees require little pruning or training. The tips of the stronger shoots are just pinched out when they have made about 6 in. of growth, but when a branch appears to be robbing the rest, or growing ahead of them, it should be shortened back or tied down.
When grown for the production of flowers, which are always in great request, the plants must be treated in a similar manner to that already described, but may do without bottom heat.
For details of orange varieties, cultivation, &c., see Risso and Poiteau, Histoire et culture des orangers (edited by A. Du Breuil, Paris, 1872); for early history and diffusion, G. Gallesio, Traite du citrus (Paris, 1811). A useful modern handbook is Citrus Fruits and their Culture, by Harold Hume (New York, 1907).
There are many varieties of the sweet orange that may be grown under glass in the British Isles. Amongst the best for dessert is the St Michaels, a heavy cropper with large juicy fruits; and closely related are Bittencourt, Egg, Dom Louise, Sustain, Excelsior and Brown’s Orange. The White Orange,
