|Allium cepa subsp. var.||Onion, Scallion, Shallot, Spring onion|
Allium cepa is also known as the "garden onion" or "bulb" onion. It is grown underground by the plant as a vertical shoot that is used for food storage, leading to the possibility of confusion with a tuber, which it is not.
|Standard Cyclopedia of Horticulture|
Allium cepa, Linn. Common Onion. Tall, with large tubular lvs.: scape glaucous, much overtopping the lvs., swollen near middle; fls. white or bluish in a large globular head-like umbel: bulb not making many offsets, distinctly rounded at top and bottom. Var. bulbellifera, Bailey, has bulbels in the place of fls.,—the top, tree or Egyptian onion. Var. multiplicans, Bailey, has dividing bulbs,—the multiplier onion. Persia and adjacent regions.CH
Prefers a sunny sheltered position in a rich light well-drained soil[1, 16]. Prefers a pH of at least 6.5. Plants tolerate a pH in the range of 4.5 to 8.3. Onions are best grown in a Mediterranean climate, the hot dry summers ensuring that the bulbs are ripened fully. For best growth, however, cool weather is desirable at the early stages of growth. Plants are frost-tolerant but prolonged temperatures below 10°c cause the bulb to flower. Optimum growth takes place at temperatures between 20 and 25°c. Bulb formation takes place in response to long-day conditions. Plants are perennial but the cultivated forms often die after flowering in their second year though they can perennate by means of off-sets. The onion was one of the first plants to be cultivated for food and medicine. It is very widely cultivated in most parts of the world for its edible bulb and leaves, there are many named varieties capable of supplying bulbs all the year round. This species was derived in cultivation from A. oschaninii. Most forms are grown mainly for their edible bulbs but a number of varieties, the spring onions and everlasting onions, have been selected for their edible leaves. There are several sub-species:- Allium cepa 'Perutile' is the everlasting onion with a growth habit similar to chives, it is usually evergreen and can supply fresh leaves all winter. Allium cepa aggregatum includes the shallot and the potato onion. These are true perennials, the bulb growing at or just below the surface of the ground and increasing by division. Plants can be divided annually when they die down in the summer to provide bulbs for eating and propagation. Allium cepa proliferum is the tree onion, it produces bulbils instead of flowers in the inflorescence. These bulbils have a nice strong onion flavour and can be used raw, cooked or pickled. Onions grow well with most plants, especially roses, carrots, beet and chamomile, but they inhibit the growth of legumes[18, 20, 54, 201]. This plant is a bad companion for alfalfa, each species negatively affecting the other. Members of this genus are rarely if ever troubled by browsing deer.
Onions may be grown from seed or, more commonly today, from sets started from seed the previous year. Onion sets are produced by sowing seed very thickly one year, resulting in stunted plants that produce very small bulbs. These bulbs are very easy to set out and grow into mature bulbs the following year, but they have the reputation of producing a less durable bulb than onions grown directly from seed and thinned.
Seed-bearing onions are day-length sensitive; their bulbs begin growing only after the number of daylight hours has surpassed some minimal quantity. Most traditional European onions are what is referred to as "long-day" onions, producing bulbs only after 15+ hours of daylight occur. Southern European and North African varieties are often known as "intermediate day" types, requiring only 12–13 hours of daylight to stimulate bulb formation. Finally, "short-day" onions, which have been developed in more recent times, are planted in mild-winter areas in the fall and form bulbs in the early spring, and require only 9–10 hours of sunlight to stimulate bulb formation.
Either planting method may be used to produce spring onions or green onions, which are the leaves of immature plants. Green onion is a name also used to refer to another species, Allium fistulosum, the Welsh onion, which is said not to produce dry bulbs.
The tree onion produces bulbs instead of flowers and seeds, which can be planted directly in the ground.
Pests and diseases
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- Bulb onion – Grown from seed (or onion sets), bulb onions range from the pungent varieties used for dried soups and onion powder to the mild and hearty sweet onions, such as the Vidalia from Georgia or Walla Walla from Washington that can be sliced and eaten on a sandwich instead of meat.
- Multiplier onions – May refer to perennial green onions, or to onions raised from bulbs that produce multiple shoots, each of which forms a bulb. The second type is often referred to as a potato onion.
- Tree onion or Egyptian onion - Produce bulblets in the flower head; a hybrid of Allium cepas.
- Welsh onion – Sometimes referred to as green onion or spring onion, although these onions may refer to any green onion stalk.
- Yellow onion - generally tapered ends, brown skin over the onion, usually sold in 3 lb bags of yellow webbed plastic.
- Sweet onion - flatter ends and sold individually. Spanish and Vidalia
- Plants for a Future - Source of some Creative Commons text on this page.
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
Standard Cyclopedia of Horticulture
|Standard Cyclopedia of Horticulture|
Onion. All the onions of common or general cultivation are forms of one variable species, Allium Cepa (see Allium, Volume I). It is probably native to south-western Asia, but it has been long domesticated and has varied much. Other cultivated species are A . fistulosum (Fig. 2583), A. Porrum (Fig. 2484), and A. Schoenoprasum (Fig. 2585).
The onion is grown primarily for its bulbs, but the leaves are sometimes used as seasoning and in stews. Under long-continued cultivation and selection, the bulbs have developed into large and shapely organs. Now and then the bulb does not develop and the neck (or stalk just above the bulb) remains relatively thick: such onions are "scullions." Seeds from poorly selected or deteriorated stock may be the cause of scullions: they are to be considered as reverted or run-down forms. Sometimes scullions result from very wet soil, whereby the plants grow too much to top. Seeds grown in the South or in a long-season climate tend to produce plants in short-season regions that do not "bottom" before caught by frost.
The onion is one of the hardiest of vegetable-garden plants. In the southern climates it is grown largely as a winter crop. In the northern states and Canada the seeds are sown or the bulbs planted as soon as the ground can be fitted in the spring. It is always best, if possible, to prepare the ground in autumn in order that the seeds may be sown on the first approach of warm weather. When onions are grown from seeds, it is essential that the ground be fine and loose, and all surface stones and litter removed. The seeds are small and do not germinate quickly. The young plants are surface feeders. If the seed is sown late or if the ground is droughty, the plants will either perish or make no headway. Land that is foul with weeds should not be planted to onions, for the young onion plants cannot withstand such competition. In the old-fashioned gardens, it was the custom to plant onions in short rows crosswise of raised beds. This entailed an endless amount of small hand labor and usually resulted in the expenditure of more time and effort than the onions were worth. The better method is to grow the plants in long rows which are far enough apart to admit of the use of a wheel-hoe. Even when a small quantity of onions is desired, it is better to place them all in one row than to have many short rows. With the best of land and management, and with the use of wheel-hoes, more or less finger work will be necessary in order to bring the crop to full perfection. The seed may be sown thick in the home garden, and as the young plants begin to crowd, they should be thinned. The plants taken out in the second and third thinnings may be used on the table (Fig. 2586). It is very important that the best grade of seed be used, for the onion deteriorates rapidly from seed which is not well grown nor carefully selected. There are great numbers of varieties. For early use and for variety, great numbers of kinds may be selected from reliable seed catalogues. Some of the quick-growing southern onions are excellent for early use. Forms of onions are shown in Fig. 2587.
There are two general methods of propagating the onion by seeds and by bulbs. Onions grown from seeds are ordinarily called "black seed onions," although there is no onion seed that is not black. The main field crop is grown from seeds, as explained in the articles which follow. The onion seed of the market is produced from full-grown and typical bulbs of the desired variety. These bulbs are grown from seed and are kept over winter as other onions are. In the spring they are planted in rows 2 feet apart and as near together in the row as they will stand. They send up a flower-stalk which blooms in early summer (Fig. 2582), and the seed is harvested.
Propagation by bulbs is employed for the purpose of securing early onions for home use or for the special early-season trade. Until within recent years, all the very early or bunch onions were raised from bulbs, but recently a so-called "new onion-culture" has come into vogue, which consists in sowing seeds in hotbeds or coldframes and transplanting the young plants. Bulb- propagation is of three general categories: (1) The use of bulbets or "top onions" which appear on the top of the flower-stalk in the place of flowers; (2) the use i of 1 mil ids or separable parts of an onion bulb, known as "multipliers," or "potato onions;" (3) the use of ordinary bulbs which are arrested in their growth, known as "sets."
Bulblets, or top onions, are shown in Fig. 2588. If one of these bulb lets is planted in the spring, it quickly produces a young bulb, and the growing bulb may be pulled at any time and eaten. If allowed to remain in the ground, however, it sends up a stalk (either the first or second year) which bears a cluster of bulblets, sometimes mixed with flowers, on its top. There are two or three strains of top onion on the market, although the leading ones are the white and the red, these names applying to the color of the bulblets. The so-called "Egyptian onion" is a top onion; also the "tree onion."
Multipliers are shown in Figs. 2589, 2590. Instead of containing a single "heart" or core, as in most onions, it contains two or more. When the onion is planted, each of these cores or bulbels sends out leaves and grows rapidly for a time; that is, the old or compound bulb separates into its component parts. The growing bulbels may be pulled and eaten at any time. If allowed to remain in the ground, each of these bulbels will make a compound bulb like that from which it came. Sometimes flower-stalks are produced from multiplier or potato onions. The best results with multipliers are secured when the bulbels are separated on being planted, for each one has room in which to grow. Two or three kinds of multiplier onions are known, the variation being chiefly in the color of the bulb.
Onion sets are merely ordinary onions which are arrested in their growth, and when planted will resume growth. They are grown from seed. The seed is sown very thick on rather poor land, so that the young bulbs soon reach the possibilities of their growth; they mature when still very small. These small bulbs or sets are then harvested and kept over winter, and used for planting the following spring. When planted, they grow rapidly and may be pulled and used for the table. If allowed to remain in the ground, they send up flower- stalks and produce seeds as do common onions. Sets are not allowed to seed, however, since the seeds from sets would probably produce an inferior race of onions. Any variety of seed-bearing onion may be grown and propagated as sets, although there are relatively few that give uniformly good results. In the trade, onion sets are usually designated as yellow, red, or white. In order to secure good results from onion sets, it is essential that the sets be small and firm. They should not be over ½ inch in diameter, if they are of the best. If they are much larger than this, they tend to run to seed rather than to produce bulbs. Sometimes the very small and inferior onions are saved from the regular crop and are used as sets the following spring. Such sets are generally known as "rareripes." Usually they do not give the best results.
The varieties of onions are numerous. Some of the forms of bulbs are shown in Fig. 2587. In 1889 ("Annals of Horticulture") seventy-eight varieties of "seed" onions were offered by American dealers, and also about twenty kinds of multipliers, potato onions, and sets. For purposes of careful scientific study, the varieties may be classified into geographical races, but for purposes of description they may be assembled into groups characterized by such arbitrary features as form and color of bulb. Goff (Sixth Report of New York State Experiment Station, for the year 1887) classifies first by shape of bulb and then by color. He makes four primary groups: bulb oblate, spherical, top-shape, oval or pear-shape. Each of these groups is divided in three sections: color white, yellow or brownish, red or reddish. Another classification (Bailey, Bull. No. 31, Mich. Agric. College, 1887) makes three primary sections on methods of propagation: propagated by division (multipliers), by bulblets or "tops," by seeds (or sets). The last section (seed onions) is divided into bulbs silvery white and bulbs colored, and these groups are again divided on shape of bulb.
When onions are grown continuously on the same land they are likely to become seriously affected with smut. Rotation of crops is the fundamental remedy. Sulfur and lime drilled into the soil with the seed at the rate of one hundred pounds sulfur and fifty pounds air- slaked lime to the acre, is also helpful. The smut may kill the young onion plants outright. The onion mildew causes wilting or blighting of the leaves, without the black pustules caused by the smut. Bordeaux mixture is the standard remedy; a "sticker" should be added to the mixture.
Aside from the chapters on onions in the vegetable- gardening manuals, there are special treatises, as Greiner's "Onions for Profit," and "The New Onion Culture;" Greiner and Arlie's "How to Grow Onions," the Orange Judd Company's "Onion Book," Gregory's "Onion Raising;" J. P. Underwood's "Onion Culture."L. H. B.
The new onion-culture (transplanting process).
The idea of raising onions by growing seedlings in beds and transplanting to the open, which are the essential features of what has been termed "the new onion-culture," is not new. It has long been put in practice in the Bermudas, among the Portuguese growers in California, and in various places in Europe. This, however, does not detract from the fact that the writer, as well as W. J. Green, of Ohio, rediscovered (about 1889) this old plan or method of onion-growing, which was then unknown in their localities and also in most parts of the United States. There are only few, if any, modern innovations which have left an equally deep impression on our garden practices. The transplanting method is admirably adapted to the character of the large foreign onions, especially those of the Spanish type, and by it the American grower is enabled to produce bulbs in every way the equal of those large sweet onions which are imported from Spain and other foreign countries, and sold in our groceries at 5 to 10 cents a pound. Some of the onions now sold to the unsuspecting buyer in various places as "imported Spanish" may be really nothing more than these home-grown bulbs of the Prizetaker variety, and the buyer is not the loser by any means. This Prizetaker is perhaps the best of this class of onions to be grown by the transplanting process at the time of writing—large, of good shape, perhaps a little darker in color than the imported Spanish, and its equal in mildness of flavor. The newer Gibraltar is still larger, milder, a little later, not so good a keeper, but altogether one of the best onions which the home-grower, as well as the market-gardener who can sell his crop before late fall and at good prices, could produce.
The plants should be started under glass (preferably in greenhouse) during January or February, sowing seed rather thickly in drills ½ or 2 inches apart, and using about an ounce of seed to 10 square feet of bed- surface. The soil should be sandy and very rich. Keep the plants in good growth, and as soon as the patch outdoors can be properly prepared in spring, set the seedlings in rows about \£ inches apart, and from 3 to 4: inches apart in the rows. Little hand-weeding will be necessary, but the wheel-hoe should be used freely. Green or bunching onions are also often grown in this way. For that purpose the plants are set more closely in the rows, not over 2 inches apart. Seed of the Prize- taker is mostly grown in the United States, while that of others is as yet all imported. T. Greiner.
Commercial onion-culture in the North.
The soil for onion-culture should be a rich, moist, but not wet, loam with a subsoil of clay, or close compact sandy loam, not coarse gravel, as that lets the water leach out too quickly. Onions will stand a large amount of fertilizing, and there is little danger of getting the soil too rich. Soil that has been under cultivation for three or four years at least is much better than new land. The tendency of the latter is to produce too much top-growth and improperly ripened bulbs.
To prepare the soil, plow 10 or 12 inches deep, if the soil is of sufficient depth, or down to the subsoil. Care should be taken not to turn up much subsoil, or the crop will not mature evenly.
If the soil is poor, plow in 5 to 10 cords of stable manure to the acre, and spread on an equal amount of well-rotted manure after plowing, to be harrowed in. Unleached hardwood ashes is also a good fertilizer, especially on rather dry land, as it aids in the conservation of moisture. The action is quick, which makes it valuable where a little of the subsoil has been turned up in plowing, giving the young plants a good start, when, without it, they would be too light-colored and weak in growth. Ashes should be spread as evenly as possible, seventy-five to one hundred bushels to the acre on the ground after plowing, and harrowed in.
The harrowing should be thorough, using some kind of a disc or spring-tooth, for the first time over, with a Meeker or some other smoothing-harrow for the finish. It is impossible to get a good even stand of plants if the ground is rough or lumpy, while those that do grow are weak and puny on rough ground. Hand-raking is sometimes necessary to insure germination of seed in a satisfactory manner.
The drainage must be nearly perfect, to get best results. There should be no hollow places in the beds. Even on a sloping piece of land, the dead-furrows or alleys should be kept open to a depth of 8 or 10 inches, and evenly graded so the surplus water will all drain off. If there is a natural sag in the land which cannot be surface-drained, it is often practicable to underdrain so as to get satisfactory results; for there is no crop grown in the ordinary market-garden which will pay a larger percentage of return for underdraining, in nearly all locations. If the foliage is of a light color, and the crop does not ripen evenly, an underdrain will usually correct the trouble. The time to drain is when the ground is being prepared for planting, not after a heavy rain, when water is standing in pools over the field.
The time to plant is as early in the spring as the soil becomes in good working condition. The common spring frosts and snow flurries will do no harm if other conditions are right.
There are a few growers who can profitably grow their own seed, but the masses should buy. This should be done early, so that there may be no delay at planting time, and also that one may get the best stock obtainable. If one wants ten pounds or more, it is sometimes advisable to order from some one of the large seed houses of the country, but if there is a reliable local dealer who buys seed in bulk, one can often do better than to send direct to the large seed house, even on quantities of fifty to one hundred pounds. Be sure to know where the seed comes from, and if possible test it before planting. In any case, always buy the best seed obtainable, no matter if it costs double the price of other stock.
The sowing of the seed should be done with one of the standard garden seed drills, the first essentials of which are that the machine can be regulated to sow evenly and in the quantity desired without clogging. The machine should open a row, sow, cover, roll, and mark the next row, all at one operation. The machines which have a sliding piece at the bottom of the hopper, which opens and closes a diamond-shaped opening, are the best, as the operator can regulate exactly the amount of seed sown.
The seed should be sown in rows 12 to 14 inches apart, and at the rate of three and one-half to four and one-half pounds to the acre, according to soil and seed. A soil which produces heavy tops requires less seed than the drier, sandy soil which grows small tops. The plants should stand from 1 to 3 inches apart in the row. The seed should be sown from ½ to 1 inch deep, according to soil. Cultivation should begin as soon as the plants are up enough for the rows to be seen. Begin with a double- wheel straddle cultivator if one is at hand, setting the knives as closely as can be worked without covering the young plants, and continue as often as necessary to keep weeds destroyed and the ground loose on top until the plants are too large to get through. The last time through may be done with a single-wheel machine, which will throw a Little earth up to the plants. A single-wheel machine may be used throughout the season, but the double-wheel is preferable for the first part of the work.
On light soil, a hand-weeder may be used with profit after the young plants have reached 3 to 5 inches in height. This works two rows at one passage, stirring the soil in the rows where the wheel-hoes do not work, and greatly reduces the amount of hand-weeding to be done. Of course, hand-weeding must be done as often as necessary to keep the beds clean.
Harvesting may be done in the following manner: If the crop ripens evenly, so that there are no green tops standing, the topping can be done most rapidly before the onions are pulled. By using a thin, sharp knife, taking the dry tops in one hand and cutting from the person, the work can be done quickly and well. Be careful not to tear the skin down the side. The length to cut the tops is a point of importance and must not be overlooked. If the tops are left too long they have a ragged appearance, and if too short, there is danger of causing the onions to rot in the tops, because of bruising or because of water having gone to the inside of the onions. The proper length is about Yi inch from the bulb; or, take an onion by the top, with the thumb and forefinger close to the bulb, and cut the top close to the fingers The pulling may be done by hand, but a puller made to fit a hand-cultivator is much more rapid and does not injure the bulbs. The puller is simply a curved knife with one or more fingers to move the bulbs slightly after the roots are cut. In light dry soil it works very well without any fingers.
Many growers prefer to pull the onions first, allowing them to dry a few days before topping. This is what should be done if the tops do not dry evenly, or if the crop is late and needs to be hurried; and is all right in any case, though not quite so rapid as the other way.
After the onions are topped, they should be gotten under cover as soon as possible. Let them dry a day or two if the weather is favorable and then pick them up and store in the curing-shed. If allowed to lie too long on the ground the skin peels off too much. The shed should have doors or ventilators at each end from top to bottom, so that the air can pass through freely and be free under the floor. If the floor is tight, with no circulation under it, lay some 2 by 4 scantling on the floor and lay a loose board floor over them without nailing; then take some pieces of 2 by 4 sawed just 1 foot long and nail them to the floor at even distances for posts to carry stringers for the next floor. Use 2 by 4 for the stringers; set them on edge, nail them to the posts and all is ready for the onions. This gives a space of 16 inches. Fill 12 inches (the length of the posts) and leave the 4 inches for air-space. Lay another floor and proceed as before, being careful to get the upper posts directly over the lower ones, or the stringers will break after two or three floors are in.
In handling the onions, bushel boxes are the most convenient. Pick them up in common baskets, leaving all small, defective, or odd-colored bulbs on the ground, to be picked up separately and sorted as occasion may require. Dump in the boxes, then drive along the side of the bed with a platform wagon, and load. Have a screen about 4 feet long by 2 feet wide made of narrow strips ½ to 1 inch wide and about 1 inch apart and the sides 10 inches high. Put legs on one end about 14 or 1.5 inches long and on the other end long enough to give it a sufficient incline to make the onions roll down freely. With an old coffee sack, make a bag like a sheet hung by the corners with hooks, to hang under the screen, in order to catch the dirt and leaves. Carry the boxes of onions directly from the wagon to the screen and pour them over it, moving the screen back as the floor is filled to the proper depth. This will take out all the dirt and most of the loose leaves, and make the onions come out of the shed in much better shape. They should lie in the shed until they are dry enough to peel off another skin, and rattle and crackle when the arm is run in among them.
If all has gone well, the crop should average 500 bushels to the acre on good land, or 600 bushels on very rich land, and 700 or 800 bushels on a single acre selected from the best part of a 10-acre field.
There is an old saying, "the time to sell is when someone wants to buy." This is a very good rule to apply, unless one is prepared for cold weather or is reasonably sure of an advance in price. In a general way, it is best to ship in sacks of even size and not too large, one and three-fourths to two and one-fourth bushels. These points must be governed by the market. In sacking to ship, always throw out all defective bulbs and all of another color. In size, down to about 1½ to 1¼ inches in diameter is a good scale to use in a general way, but this point must also be governed by the market. Sell by sample so far as possible.
There are three varieties of onions which take the lead clearly above all others in the big markets of the country,—the White Globe, Yellow Globe, and Red Globe. These come under different names, as South- port Yellow Globe and Michigan Yellow Globe, but the object in view among seed-growers is to get bulbs as nearly globe-shaped as possible. The skin should be thick and two or three layers deep, to prevent bruising.
Onion-culture in the South.
Twenty years ago onion-growing from seed was not considered practicable, and by many it was considered impossible south of the Potomac. The introduction of varieties from southern Europe and more careful attention to details of the work have made onion-growing not only possible but often exceedingly profitable.
The eastern South consumes large quantities of the mild forms, such as the Bermudas. In the markets at Jacksonville, Florida, these are sold by the piece, frequently retailing at 5 cents and 10 cents each. The southern onion-grower must keep in close touch with the northern and foreign onion markets. In the humid regions of the South, there is a considerable risk from unseasonable rains. In the drier regions, such as a part of Texas, it becomes a very important and remunerative form of vegetable-growing. They have developed onion-growing most extensively and have organized the marketing arrangements most perfectly there.
The soil should be alluvial, sandy, and of a fine texture. A level tract, freed of all debris, and one that can be plowed deeply, is desirable. In the coast regions such land may be obtained in great abundance. It is frequently used for vegetable-growing, but large areas are still uncleared or are used for farm crops. In the hilly regions of the interior, onion lands must be sought mainly along rivers or old river-beds.
Undecomposed vegetable matter should not be applied immediately preceding the crop. Even cottonseed meal should be used three weeks or more before the seed is sown and then carefully incorporated with the soil where the rows are to be, or if the rows are to be a foot or 14 inches apart the cotton-seed meal may be sown broadcast and cultivated in.
Seed-sowing in the field occurs in the upper districts as early as the first of April or a little earlier, in the central district about the last of February, while in the Gulf region it may occur late in fall or any tune during the winter, being gauged largely by the time required for the variety to mature, and the market to be met. It is a good rule to put on an abundance of seed, about twice as much as recommended in general, especially in the Gulf region. Many fields suffer from deficient stand more than from any other cause, and in some years it is the only cause for an unprofitable crop.
Good crops may be grown from sets, but the labor involved and cost of the "seed" is usually so great as to deter many from planting them. In using sets, they should be separated into three or four grades, the largest size maturing earliest and the smallest last. In most cases the smallest sets grow such inferior onions that they had better be discarded. This takes for granted that the sets were all grown at the same time and from the same seed in one field.
Nearly all the onion sets used in the South are shipped in, while they may be grown as well here as anywhere. In the Gulf region there is time enough to grow a crop of sets after the northern crop has been harvested and marketed. Thus in case of shortage in northern-grown sets, it is entirely practicable to ship the seed South, grow sets, and ship sets back in time for spring market.
Much has been written and spoken about raising the plants in a seed-bed and then transplanting to the field. While this may be practised successfully, the greater quantity of onions is raised by the old-fashioned method, i. e., by seeding in the drills where the plants are to mature bulbs. In certain localities it is advantageous to plant out a seed-bed before the general field will permit working, and then transplant as soon as all conditions are favorable. In the upper districts of the South, seed may be sown in hotbeds as early as the first of February, and the plants may usually be set out by the first of April. In the central South, seed may be sown in protected coldframes as early as the middle of December, or in an open bed in February. The earlier plants may be transferred to the field by the last of February, or as soon as danger from frosts is past. In the Gulf region the seed may be sown during the fall in an open bed, and transplanting to the field may occur when plants are of proper size and favorable condition of weather prevails.
Harvesting is often attended with considerable difficulty, and in some cases special drying-houses have to be constructed to secure the crop in first-class condition. The crop is a perishable one, and must be pulled, gathered and shipped in as short a time as possible, when sufficiently mature. There seems to be no generally accepted plan for marketing, the crop being placed hi boxes, barrels or bags for shipping.
The following varieties have given good crops in the hands of expert growers and may be recommended for the entire South: White Bermuda, Red Bermuda, Prizetaker, Yellow Danvers, Giant White Italian, Giant Rocco. and Large Tripoli. Other varieties than those named here have given as good or better returns, but do not seem to have been so generally successful. Additions are Red Bermuda (Fig. 2591) for Gulf region and Red Wethersfield for central and upper district.
Black mold (Macrosporium Porri) is a disease which spreads rapidly over the field, especially late in the season. Some good may be done by spraying with bordeaux mixture, but its application is limited almost to the diseased portion.
Another disease attacking onions is smut (Urocystis cepulae). The name of this fungus describes it fairly well. About all that can be done is to subject the field to rotation, and to sow seed from smut-free districts. Some years nearly all southern-grown onions brought to market will be more or less infected.
Rotting is especially severe in wet seasons when the crop cannot be properly handled, and is caused by a number of fungi. The best preventive is to store in a dry place, and consume as soon as practicable.
Onion fly, or onion maggot, is one of the most severe pests when it enters the field. There seems to be but little encouragement in combating the pest. It often leaves the field as mysteriously as it appeared. This disappearance has been coincident with the application of some supposed remedy, and has consequently led to the recommending of unreliable remedies. A thorough application of ground tobacco stems down the row seems to act as an insecticide and a repellent, besides being of value as a fertilizer. Thrips attack the leaves at times, and become so numerous as to cause the tips to turn brown and finally destroy the whole leaf. Besides the insect injury they open the way for such fungi as Macrosporium. This insect may be treated successfully with kerosene emulsion, tobacco decoction, resin wash and possibly with kerosene-water mixture.
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