EXTERMINATING PESTS Spraying Mixtures.—No matter where grown, all kinds of fruit are attacked by pests. In mild, humid atmospheres tree pests are usually of a fungoid nature ; in the dry, warm regions insects and bacteria are rife. In temperate zones all three are present. All parts of the fruit trees suffer, including the foliage, the blossom, and the fruits; where the last named are affected their value is considerably reduced. Apples, for instance, holed with the codlin moth, a pest very prevalent in box apple dis tricts of America, or spotted with scab, as is common in Great Britain and the eastern district of America and Canada, are practically valueless and would be culled out in grading. Sim ilarly, cherries with worms of the cherry fly, and gooseberries covered with mildew are of little value.
The fruit grower who would produce high grades of fruit has to carry on a regular campaign to keep pests under control. For deciduous fruits like apples, pears, plums, cherries, gooseberries and currants, etc., a series of sprays on the trees is regularly practised in all districts. One spray, called the winter spray, is applied when the trees and bushes are dormant, and other sprays in the spring and early summer when the foliage is developing or out. Formerly sprays of lime, lime and salt, lime and sulphur and caustic soda were used as winter sprays, but whilst all these sprays would cleanse the trees and bushes of lichens and mosses, would kill any adult insects that were hiding, they either had no effect on the insect eggs or killed a few only, for which reason they have been supplanted by sprays of a coal tar distillate type. These tar distillate sprays, mixed with water for top fruits in the ratio of 72 of spray fluid to 921 water and applied to the trees when dormant, kill the lichens and mosses, adult insects, and the eggs of most of the insects which attack fruit. The same fluid in the ratio of 5 of spray to 95 water may also be used for bush fruits. This discovery has placed a most efficient spray at the service of fruit growers and large quantities are now used as winter sprays. The proprietary washes known on the English markets as Carbokrimp,. Mortegg, Ialine, Aboline, and Sterolite are of this class.
The first of the summer sprays is applied to the apple trees when the blossom buds are just developing and a second is made immediately after the petals have fallen, and repeated, if neces sary, in two to three weeks' time. Pears and other top fruits are the better for being treated similarly. The spray used is Bor deaux mixture-4 lb. copper sulphate, 4 lb. quicklime, and 5o gal. of water into which 2 lb. of lead arsenate has been added. The Bordeaux-arsenate mixture sticks to the foliage and pro tects it against fungus diseases like scab and leaf eating cater pillars and all biting insects. Instead of the Bordeaux mixture many growers prefer to use a lime-sulphur spray, which is safer for tender varieties, such as Cox's Orange Pippin, James Grieve and Rival. Lime sulphur, one gal. to 29 gal. of water, is largely used for spraying gooseberry bushes to prevent mildew and for black currant bushes (one part lime-sulphur to r 2 parts of water), to control the bud mite.
Spraying must be thoroughly and intelligently done, and that largely is a matter of understanding the technique and having suitable machinery. The sprayers may vary in size from a small knapsack costing £3, or a barrel on wheels with a hand pump costing £20. or a large portable machine with pump (motor) cost ing over £ i oo. Pumps which release the spray from the nozzle at a pressure of 200 lb. are the more efficient. These repeated sprayings have become a necessity and no growers could now succeed without them in producing high grade clean fruits. (See also under APPLE GROWING, etc.) . (H. V. T.) With the wide range of climatic and soil conditions in the United States, it is possible to grow to perfection in one part of the country or another most of the temperate zone fruits and many others of semi-tropical origin. It is not surprising, therefore, that fruit growing occupies an important place in the agriculture of the country. The total farm value of fruit and nuts in 1919 was placed at $730,000,000. The production _of some of the principal fruits is given in the following table : The combined production of all fruit has increased greatly since the beginning of the century. Keen competition has led to a gradual decline of fruit farming in the less favourable regions and a concentration in sections where natural conditions and good transport facilitate production and marketing. Farm orchards in the marginal regions are becoming less important also because little or no attempt is made to control pests there, so that the fruit is usually of low quality.
Apples are the most extensively cultivated of all fruits. They are grown commercially in all except a few of the warmest and most southern States and in the two or three northern States of the Great Plains region. Outstanding apple sections are found in New York and in parts of Ohio and Michigan adjoining the Great Lakes; Washington, and several other portions of the north-west States ; the Shenandoah-Cumberland region including parts of southern Pennsylvania, western Maryland, West Vir ginia and Virginia; the New England States; the Ozark regions of Arkansas and Missouri; southern Ohio, Illinois, Colorado and California. Pears are grown only in the cooler climates with important centres in California, New York, Washington, Oregon and Michigan. Quinces are grown in a very limited way in the same regions. Important commercial peach areas are found in Georgia, California, Texas, the Ozarks, the Carolinas and Tennes see, the Middle Atlantic States and those pars of New York. Michigan, Ohio and Pennsylvania that have the advantage of the moderating influence of the Great Lakes. Plums are most largely grown in California, Washington and Oregon, although several native species are widely distributed, yet not extensively grown, throughout the eastern States and in the upper and lower Missis sippi valley. Commercial sweet cherry production is confined to the Pacific coast while sour cherries are grown most extensively east of the Rocky mountains, especially in New York, Michigan and Wisconsin. The commercial production of apricots is carried on only in California. The important citrus regions are limited to southern and central California and southern Florida.
The American Labrusca grapes are largely grown along the shore of Lake Erie in Western New York, Pennsylvania, Ohio, and the eastern shore of Lake Michigan. Other important sec tions are found in the Hudson valley and in the Ozark region. Muscadine grapes have recently been planted largely in the southern Atlantic and the Gulf coast states, especially in North Carolina. Numerous attempts have been made to grow European grapes in the eastern part of the United States but the cultivation of this species is now confined to California, where it is the most important fruit. Large commercial areas of strawberries are found in Florida, Alabama, the Carolinas, Tennessee, Arkansas, Missouri, Eastern Maryland, Delaware, south-western Michigan and New York. Raspberries are extensively grown in Washing ton and throughout the north-eastern part of the United States with specially concentrated areas in the fruit regions around the Great Lakes and in the Hudson valley. Blackberries are grown farther south along the Ohio river in the Ozark region and in Texas. Dewberries are also grown in the Pacific States. Cur rants and gooseberries are found mostly in the Hudson river valley and in Western New York near Lake Ontario, but they are among the least important fruits. Cranberries are confined to limited areas in Massachusetts, New Jersey, Wisconsin and Long Island, N.Y. Among the cultivated fruits that have been planted on a commercial scale in recent years might be mentioned the persimmon and blueberries which are found in the temperate regions and the olive, dates, avocado, mango and loquat which are grown chiefly in California, Arizona and Florida.
The fruit industry in the United States traces back to the first settlers of America. Old world species have become well estab lished in the new country. Most of the apples and peaches grown in the United States are American varieties of European species. Foreign grapes, plums, pears, cherries, apricots are as extensively grown as are varieties developed in America. A number of the native fruits are among the important cultivated sorts notably the Labrusca and several other species of grape, several species of plums, raspberries, blackberries, dewberries, blueberries and cran berries. The strawberries are mostly hybrids of American and foreign sorts. There are many other promising native fruits which are being grown locally and which are also being used extensively by experiment stations throughout the country in breeding work. These State and Federal experiment stations have produced thousands of seedlings of fruits of known parentage the aim being to develop varieties that have fewer faults from the stand point of the grower than the existing sorts. The ideal variety combines the desirable features of high quality, productivity, resistance to extreme cold in winter, to late spring frosts, and to diseases and insects.
Orchard Methods.—Frost constitutes the greatest uncertainty in fruit growing. No fruit and no fruit section is entirely safe from unseasonable cold weather, and in occasional years even the most reliable and hardy varieties in established fruit sections suffer during the winter or have the bloom killed or seriously curtailed by late frosts in spring. Winter injury to the plant and the fruit buds is a more important problem in the northern sec tions, although there are also serious losses from unfavourable weather at blooming time. Only the hardier varieties are chosen and cultural operations are done in such a way as to insure the best maturity of fruit and wood. The proximity of large bodies of water is a most important feature of the oldest established fruit sections in Western New York, in the Hudson Valley, and in south-western Michigan. The influence of the Atlantic on the New England States and of the Pacific in the north-west also has its beneficial effects on the fruit growing industry in those parts ; frequent extremes of temperature are avoided during the winter, and in spring the buds remain dormant for a week or ten days later than in less favoured regions of the same latitude. The inland sections, notably those in the Shenandoah-Cumberland region, the Ozarks and the Mississippi valley are specially haz ardous so far as the injury from spring frosts is concerned: In favourable climates the site of a fruit farm is generally chosen with reference to its freedom from frost pockets. Orchard heating has not proved economical for deciduous orchards except in the north-west, but this method of avoiding injury from frosts is extensively practised among the citrus growers in California and Florida. By the use of 3o to 5o small oil or coal fires per acre it is possible to raise the temperature 4° to 5° F and thus prevent damage from cold. The overhead cost of heating may run as high as $50 to $75 per acre but heated citrus orchards may show a profit over a ten year period, of from 3o% to over unheated orchards.
While the climate determines whether or not it is possible to grow fruit in any locality, the soil is probably the most impor tant factor in determining the yields and profits. For most tree fruits the fertility of the surface soil is less important than is a good depth and proper drainage of the sub-soil. Most fruit growers have learned to avoid obvious defects such as shallow or impervious soil; but it is, unfortunately, difficult to predict the drainage conditions in years of unusual rainfall during late spring and late autumn, so in every fruit section one finds many orchards established on ill-suited land. Even in a given orchard trees in one row may yield two to four times as much fruit as borne by the same variety a few hundred feet removed.
The standard planting distances for mature apple trees is 4o x 4o feet. Practically all other tree fruits are set 20 x 20 feet apart. Small fruits are planted in rows far enough apart to permit cultivation by horse- or tractor-drawn implements. It is impor tant to reduce the amount of man labour required, the land being a relatively cheap item in most cases. In apple orchards, fillers or semi-permanent trees are sometimes allowed to occupy the inter vening spaces for the first 15 to 25 years after planting. In many cases intercrops such as corn, tomatoes, strawberries and the like are grown for the first 2 to 4 years. In setting out a modern fruit plantation particular attention is given to cross pollination, since many kinds of fruits will set more abundantly if they have the stimulus of pollen from another variety of the same species. Some cherry, plum and apple trees may bloom heavily but set few if any fruits without cross-pollination. The weather at blooming time may interfere with the flight of bees, or the temperature may be too low for the proper development of the young fruits, so that severe losses are not infrequently en countered even though cross-pollination has been provided.
Orchard soil management is concerned chiefly with the con servation of soil moisture and the supply of nitrogen to the plants. Early ploughing in spring and the frequent stirring of the soil during the summer is the standard procedure for most fruits. The tendency is to plough earlier in the spring and not so late in the autumn, for nitrates and moisture are thus provided at a minimum expense at a time when the tree is making most rapid growth. Cover crops of rye, oats, legumes or even volunteer crops of weeds are allowed to occupy the land during late summer and autumn. By absorbing excess moisture and plant food from the soil and thus reducing the supply to the tree the cover crop helps to mature the fruit and allows the tissues to develop hardi ness against cold. When ploughed under in late autumn or early spring the cover crop tends to replenish the humus supply of the soil. Grass interferes with the growth and productivity of the trees ; but it is possible to overcome much of this injury by apply ing readily available nitrogenous fertilizers. Many fruit growers are now turning to a method of sod culture with nitrates. Nitro gen is necessary for vigorous shoot growth; it causes the flowers to set fruit and to develop to the proper size. Peaches require most nitrogen and are the first to suffer when the element is deficient. Cherries, plums, pears and apples follow in the order given. While other elements than nitrogen, especially phosphorus and potash, are applied to fruits, they seldom prove profitable in the cultivated orchard except on very poor soils. Phosphorus seems to be especially needed by strawberries. Cultivation in most cases not only liberates adequate supplies of nitrates and other food elements for fruit plants by destroying the grass and weed growth but also tends to conserve the soil moisture by providing a dust mulch. An adequate supply of soil moisture is an important factor with all small fruits, and with tree fruits in the less humid sections of the country. Irrigation is a common practice with fruits throughout the north-west and in many parts of California, but is not used in the eastern part of the United States except for special plantings of strawberries and rasp berries.
Pruning practices vary greatly for the different fruits and for a given fruit in different sections. The present tendency is to prune young trees less severely, although it is generally recom mended that some attention be given to shaping of the main framework. Experiments have definitely shown that the heavy cutting formerly believed to be necessary to train the tree may delay bearing from two to five years. As the trees grow older, the most common practice is to remove the crowding branches and any weak, shaded or diseased wood. After a time it becomes necessary to cut back the high branches in order to confine the bearing surface within a reasonable distance of the ground and within the allotted space. Extra heavy cutting is sometimes practised to rejuvenate tall and neglected trees. Among the tree fruits, peaches and apricots receive the most frequent and the most severe cutting, to force an abundance of new shoot growth and increase the size of the fruits. While the sour cherry com monly receives the least pruning many growers find that the heavy cutting given to keep the tree small, also stimulates a desirable wood growth and provides somewhat hardier buds. Mature apples may be pruned every few years by cutting out much wood, or they may receive a more detailed pruning annually. Although it is recognized that very severe cutting may in some cases reduce the total yield, most growers seem to find that the quality of the fruit is greatly improved and orchard practice is facilitated enough to justify the costs of the operation. The pruning of grapes and bush fruits is more nearly standardized than the practice for tree fruits, heavy cutting and thinning out of old wood each year being the rule. The refinements of pruning frequently practised in Europe are not followed in the United States, chiefly because economic conditions do not permit of much hand labour and also because there seems to be little need; its problems, as well as other cultural operations, have, how. ever, been the subject of much study by the agricultural ex. periment stations in recent years. Such matters as the regularity of bearing, flower bud formation, fruit setting, growth and quality of fruit, and winter injury have been shown to be associated with the physiological disturbances caused by the removal of leaves and twigs.
Among the more important diseases which can be successfully controlled by spraying are apple-scab, bitter-rot, blotch and apple cedar rust ; peach-scab, leaf-curl and brown-rot ; black-rot on grapes; citrus scab and melanose. The various fruits are also subject to injury by sucking insects such as scales, aphids, red mite, and pear psylla as well as by a large number of biting insects among which the most important are the codling moth and the green fruit worms, plum curculio, canker worms, tent cater pillars and grape phylloxera. Fumigation with hydrocyanin gas is used for citrus scale, and peach tree borers are now controlled by the use of a volatile paradichloro-benzine which is placed about the base of the tree. A few pests such as blight, yellows and mosaics, cannot as yet be satisfactorily controlled by spray, and many troublesome insects such as fruit flies, Japanese beetles and others are being introduced in spite of rigorous quarantine, new sprays being required to hold these in check. Rodents— especially mice, rabbits and gophers—do considerable damage to the young fruit plantations and many growers find it necessary to carry on systematic control measures involving their whole sale destruction.
Large quantities of fruit, especially apples, are kept in cold storage warehouses to supply the market throughout the winter and late spring. Other fruits such as peaches, pears, plums and strawberries are held for periods of several days to a month or more. Only certain varieties are suitable for prolonged keeping and these must go into storage in proper condition. Storage scald and internal breakdown are common storage difficulties. These can be prevented by the use of oiled paper wrappers and by allowing the fruit to mature properly before storing.
The fruit drying industry is very extensive. In 1919 about 575,000,000 lb. of evaporated fruit were produced. Raisins ac counted for approximately one-half of this amount and prunes for a little less than one-fourth. Apricots, apples and peaches made up practically all of the remainder. Large quantities of the fresh fruit and of the by-products are exported to Great Britain and Germany and other European countries. Approxi mately 5,000,000 boxes and 1,500,000 bbl. of apples, about 420,000,000 lb. of dried fruits and over 225,000,000 lb. of canned fruits are exported each year.
BIBLIOGRAPHY.-Among the many modern works of a scientific Bibliography.-Among the many modern works of a scientific nature on fruits in America may be mentioned Chandler's Fruit Grow ing and Gardner, Bradford and Hooker's Fundamentals of Fruit Pro duction. The various fruit monographs published by the New York agricultural experiment station at Geneva, N.Y. are the standard ref erences for a description and history of the varieties of deciduous fruits. A recent comprehensive survey of the industry in the United States is found in the 1925 Yearbook, of the U.S. department of agri culture. The Federal and State experiment stations throughout the country have contributed largely to the advancement of the fruit industry and their numerous bulletins on insects, diseases and cultural problems are of great value. (A. J. HE.)