Corn
| Zea mays subsp. var. | Corn, Maize, Mealie, Indian corn, Sweet corn | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Upright, strong, robust stalks produce smooth strap-like leaves. Pointed-tipped leaves are up to 36 in (90 cm) long. Feathery male flowers come in terminal panicles, while female flowers come in heads up to 8 in (20 cm) long, originating from leaf axils, and packed with yellow, white, or black shiny grains, up to 10 mm across, all enclosed within the leaves. These are known as "ears" of corn.
- More information about this species can be found on the genus page.
Cultivation
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Propagation
Seed.
Pests and diseases
Insect pests
- Corn earworm (Helicoverpa zea)
- Fall armyworm (Spodoptera frugiperda)
- Common armyworm (Pseudaletia unipuncta)
- Stalk borer (Papaipema nebris)
- Corn leaf aphid (Rhopalosiphum maidis)
- European corn borer (Ostrinia nubilalis) (ECB)
- Corn silkfly (Euxesta stigmatis)
- Lesser cornstalk borer (Elasmopalpus lignosellus)
- Corn delphacid (Peregrinus maidis)
- Western corn rootworm (Diabrotica virgifera virgifera LeConte)
The susceptibility of maize to the European corn borer, and the resulting large crop losses, led to the development of transgenic expressing the Bacillus thuringiensis toxin. "Bt corn" is widely grown in the United States and has been approved for release in Europe.
Diseases
- Corn smut or common smut (Ustilago maydis): a fungal disease, known in Mexico as huitlacoche, which is prized by some as a gourmet delicacy in itself.
- Maize Dwarf Mosaic Virus
- Stewart's Wilt (Pantoea stewartii)
- Common Rust (Puccinia sorghi)
- Goss's Wilt (Clavibacter michiganese)
- Grey Leaf Spot
- Mal de Río Cuarto Virus (MRCV)
- Stalk and Kernal Rot
Species
Many forms of maize are used for food, sometimes classified as various subspecies:
- Flour corn — Zea mays var. amylacea
- Popcorn — Zea mays var. everta
- Dent corn — Zea mays var. indentata
- Flint corn — Zea mays var. indurata
- Sweet corn — Zea mays var. saccharata and Zea mays var. rugosa
- Waxy corn — Zea mays var. ceratina
- Amylomaize — Zea mays
- Pod corn — Zea mays var. tunicata
- Striped maize — Zea mays var. japonica
Gallery
Corn plants showing ears
Young stalks
Two teosintes said to be the parents of maize
Guila Naquitz Cave, site of the oldest known remains of maize
Field of maize in Liechtenstein
A corn heap at the harvest site, India
Multicolored varieties of maize
Exotic varieties of maize are collected to add genetic diversity when selectively breeding new domestic strains.
Corn shocks, or bundles, are a traditional harvest practice.
Corn male flower, a.k.a. corn tassel
Corn female flower, a.k.a. corn silk
Standard Cyclopedia of Horticulture
| Standard Cyclopedia of Horticulture |
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Corn, maize (sweet and pop). A tender annual cultivated for its grain, which is used both for human and live-stock food, and for the herbage which is used as forage. As a horticultural crop, it is grown primarily for the unripe grain or for pop-corn. The word maize, Spanish maiz, is derived from the name Mahiz, which Columbus adopted for this cereal from the Haytians. Maize has not yet been found truly wild. Its close relationship to a native Mexican grass called teosinte, Euchaena mexicana, is indicated by the known fertile hybrids between this species and maize as pointed out by Harshberger. Teosinte and the only other species which show close botanical relationship to maize are indigenous to Mexico. In fact the evidence all shows that maize is of American origin, although its original form has not yet been discovered, nor has its evolution from other types been completely traced. DeCandolle concludes that maize is not a native of the Old World but is of American origin, and that it was introduced into the Old World shortly after the discovery of the New, and then was rapidly disseminated. Very early in the exploration and settlement of the New World, the whites learned from the natives the use of maize as food. Several of the Indian names for preparations of food from this cereal were adopted or adapted by the settlers and passed into the English language,—as for example hominy, samp, and succotash. In the English-speaking colonies, maize was grown as a field crop under the name Indian corn, but later the tendency was to drop the word Indian so that this cereal is now known in American agriculture and commerce by the simple word corn. The word corn has thus come to have a specific meaning on this continent which does not attach to it in the British Isles. Corn now holds first rank among the agricultural products of the United States, both in the area devoted to its cultivation and in the value of the annual crop. The types known in garden culture in this country are the sweet corns and the pop-corns; the other types, which are more strictly agricultural, may be designated as field corns. Sweet corn and pop-corn are also grown as field crops in comparatively limited areas, the sweet corn either as a truck crop or for canning, and the pop-corn to supply the demand for this product in our domestic markets. Only the types of sweet corn and pop-corn will receive attention in this article. Botanical classification. Zea almost uniformly has been considered by botanists as a monotypic genus, its one species being Zea Mays. But Z. Mays is an extremely variable species, including groups which are separated by definite characteristics. As a working classification, that proposed by Sturtevant is the best which has yet appeared. He describes seven "agricultural species." These are Zea tunicata, the pod corns; Z. everta, the pop-corns (Fig. 1058); Z. indurata, the flint corns; Z. indenlala, the dent corns; Z. amlyacea, the soft corns; Z. saccharata, the sweet or sugar corns (Figs. 1058, 1059, 1060) ;Z. amylea- saccharata, the starchy sweet corns. Z. canina, Wats., is a hybrid form, as shown by Harshberger. Z. Mays, Linn., belongs to the natural order of grasses or Gramineae. Culms 1 or more, solid, erect, 1½-15 ft. tall, or more, terminated by a panicle of staminate fls. (the tassel) : internodes grooved on one side: branches ear-bearing or obsolete: lvs. long, broad, channeled, tapering to the pendulous tips, with short hyaline ligules and open embracing sheaths: fls. monoecious, awnless, usually proterandrous; staminate fls. in clusters of 2-4, often overlapping; 1 fl. usually pedicelled, the other sessile or all sessile; glumes herbaceous; palea membranaceous; anthers 3, linear. The ear contains the pistillate fls. on a hard, thickened, cylindrical spike or spadix (cob), which is inclosed in many spathaceous bracts (husks); spikelets closely sessile, in longitudinal rows, paired in alveoli with hard, corneous margin; fls. 2 on a spikelet, the lower abortive; glumes membranaceous; style single, filiform, very long (silk); ovary usually sessile: ear variable in length and size, often distichous; grain variable in shape and size. The color ranges from white through light and dark shades of yellow, red and purple to nearly black. Sweet corn (Zea saccharata, Sturt.). Figs. 1058-1060. This is a well-defined species-group, characterized by horny, more or less crinkled, wrinkled or shriveled kernels, having a semi-transparent or translucent appearance. Sturtevant, in 1899, lists sixty-one distinct varieties. He gives the first variety of sweet corn recorded in American cultivation as being introduced into the region about Plymouth, Massachusetts, from the Indians of the Susquehanna in 1779. Schenck, in 1854, knew two varieties. It appears, therefore, that the distribution of sweet corn into cultivation made little progress prior to the last hah" of the nineteenth century, green field corn having largely occupied its place prior to that period. Sweet corn is preeminently a garden vegetable, although the large kinds are sometimes grown for silage or stover. As a garden vegetable, it is used when it has reached the "roasting ear" stage, the kernel then being well filled and plump but soft, and "in the milk." The kernel is the only part used for human food. When sweet corn is used as a fresh vegetable, it is often cooked and served on the cob. Dried sweet corn, though never an important article of commerce, was formerly much used, especially by the rural population. It is gradually being generally abandoned for canned corn, for other cereal preparations or for other vegetables, but recently desiccated corn has been put upon the market and is finding sale in certain districts, particularly in the South and in mining and lumber camps. It is practically unknown outside North America. Sweet corn is commonly grown for canneries under contract, the canning company supplying the seed and guaranteeing it to be good and true to name, while the farmer agrees to grow a certain specified acreage and deliver the whole crop to the cannery at a stipulated price. In Iowa the price now paid the grower is about $7 per ton of good ears. A yield of three to four tons to the acre is considered good. The ears are snapped from the stalks with the husks on and hauled in deep wagon-boxes to the canneries. The stalks, when preserved either as ensilage or as stover, make excellent fodder. The overripe and inferior ears, being unmarketable, are left on the stalks and thereby materially increase their value as a stock food. The stover keeps best in loose shocks, as it is liable to mold when closely packed in large stacks or bays. As a field crop, sweet corn is grown most extensively on medium heavy loams that are well supplied with humus or organic matter. It luxuriates in rich warm soils. The crop rotation should be planned so as to use the coarse manures with the corn, which is a gross feeder. On the more fertile lands of the central corn- belt, nitrogenous manures may not always be used to advantage with corn, but in the eastern and southern states, where the soil has lost more of its original fertility, stable manure may often be used profitably with this crop at the rate of 8 or 10 cords to the acre, or possibly more. In the northern part of the corn-belt in the central and western states, that is to say north of the Ohio and Missouri rivers, deep fall plowing of corn land is generally favored, but in experiments at the Illinois and Indiana experiment stations, the depth of plowing has had little influence on the crop. In sections of the eastern states, shallow plowing late in spring is favored, especially if the land be in sod. In warmer, drier regions, as in parts of Nebraska and Kansas, listing has been much practised on stubble ground. The listing plow, having a double mold-board, throws the soil into alternate furrows and ridges, the furrows being 8 or 9 inches deeper than the tops of the ridges. The corn is planted in the bottom of the furrow, either by means of a one-horse corn-drill or by a corn-drill attachment to the lister plow, consisting of a subsoil plow through the hollow leg of which the corn is dropped. Great care should be used to secure seed-corn having high vitality as a precaution against the rotting or weak germination of the seed in the soil, should the season be cold and wet after planting. Select the seed- ears early before any hard frosts have come. At this time the large, early, and well-matured ears can be distinguished from the rest of the crop, as the husks about the early-maturing ears will have started to turn brown. Early maturity is a vital point to consider in selecting seed-ears and this quality should never be sacrificed for the size of late unmatured ears. In selecting seed for a field crop, seek systematically for stalks having little or no growth of stools and bearing single, large, and early-maturing ears. For garden use, seed from more productive stalks is desirable, even though the ears be smaller. The seed-ears should be dried at once by artificial heat so that the seed may better withstand unfavorable conditions of temperature or moisture. In many, localities so-called kiln-dried seed is much in favor. In the North, sweet corn should be planted as early as can be done without involving great risk of loss from frosts or from rotting of seed in the soil. In New York, field-planting is generally done from May 10 to May 20; in central Minnesota from May 10 to May 30. The ground having been plowed and prepared so as to make a seed-bed of fine, loose soil 3 inches deep, the seed should be planted to a depth of 1 to 3 inches. The drier and looser the soil, the greater should be the depth of planting. In planting small fields, the ground may be marked in check-rows so that the hills planted at the intersection of the rows will stand about 3 feet 4 inches to 3 feet 6 inches apart each way, and the corn planted by a hand-planter, which each time it is thrust into the ground drops from four to five kernels, which is usually the number desired. Three feet apart is too close to allow the cultivators to work easily. For large fields, the check-row type of planter should be used. These planters drop and cover the seed in hills at uniform distances apart, planting two rows at one trip across the field. Two types of furrow-openers are now used on corn-planters; these are the runner furrow- openers and the disc furrow-openers. The former are less satisfactory on sod land or in fields covered with trash, as the runners will often ride out and leave the seed uncovered. It is better to use the disc furrow- opener on such land; besides opening the furrow better, it also pulverizes the soil about the seed. Field corn is often planted in drills by planters adapted to this purpose, but sweet corn should be in hills so that the surface of the ground may be kept loose and entirely free from weeds. Till for the purpose of retaining soil-moisture as well as to kill weeds. This requires frequent shallow cultivation, pulverizing the surface of the soil so that it will act as a mulch to retard the evaporation of soil-moisture. Tillage should begin as soon as the planting is done, using the slanting-tooth harrow and the weeder types of implements until the corn is nearly 6 inches high, providing that the weeds are small and the ground is in friable condition. After this time the spring-tooth cultivators or the two-horse cultivators, having preferably three or four shovels on a side, are generally used, depending somewhat upon the kind of soil to be cultivated. This type of two-horse cultivator is preferable to the double-shovel type which was formerly much used. The two-horse revolving disc cultivator is sometimes used in damp, weedy ground. One great objection to this type is that too much earth is thrown toward the corn and the middles between the rows are usually left either untouched or bare of the loose soil which is needed for a mulch. For the later cultivations the two-horse surface cultivator is coming more and more into general use. Till at intervals of seven to ten days. At first the cultivator may run from 2 inches deep near the plant to 4 inches deep midway between the rows. Each successive cultivation should gradually increase in depth towards the middle between the rows; throw ½ inch or more of earth towards the corn and cover the weeds. At the last cultivation the cultivator may be kept a little farther from the corn. It should leave the soil pulverized to a depth of 2 to 3 inches over the entire field. The earlier cultivation may be deepened, if necessary, to kill weeds, even though some corn roots are severed, but cutting the roots by deep cultivation near the plants late in the season is to be especially avoided. Till the soil until the corn gets so large as to prevent the use of a two-horse cultivator. Occasionally a later cultivation, with a one-horse cultivator, may be necessary if heavy rains leave the surface soil hard and start the weeds. Often catch-crops for late pasturage, cover-crops or crops of winter wheat or rye are sown in the cornfield and cultivated in with the last cultivation. The seed is covered deeply by cultivating it in because the weather is apt to be dry at this period. The lower part of the furrow-slice is thus left compact, furnishing a compact seed-bed, in which small grains delight. The cultivation of sweet corn in the garden should follow the general lines indicated for field culture, but stable manure and commercial fertilizers may be used more liberally. Except on very fertile soils, it is well to put a small amount of a complete commercial fertilizer in each hill and mix it well with the soil before planting the corn. A fertilizer which has a large amount of nitrogen in quickly available form should be chosen for this purpose. Dwarf early-maturing varieties may be planted, for early use, as soon as the ground is sufficiently dry and warm. A little later, when the ground, is warmer, the second-early main crop and late varieties may be planted. Later successional plantings insure a supply of green corn till frost kills the plants. Corn is not grown commercially as a forcing crop. Attempts to force it in winter have not given encouraging results, but it may be successfully forced in spring, following any of the crops of vegetables which are grown under glass, providing the houses are piped so as to maintain the minimum night temperature at 65° F. Provide good drainage. Give a liberal application of stable manure and thoroughly mix it with the soil. In the latitude of New York the planting may be made as early as the first of March. As soon as the first leaf has unfolded, the temperature may be allowed to run high in the sun, if the air is kept moist by wetting the floors and walls. The glass need not be shaded. Keep night temperature close to 65° F., not lower and not much higher. After the silk appears, jar the stalks every two or three days, when the atmosphere is dry, and thus insure abundant pollination. Early maturing varieties, like Cory, give edible corn in about sixty days when thus treated. Corn may be forced in the same house with tomatoes, eggplant, and other vegetables which require similar range of temperature. Varieties of sweet corn. Some of the desirable varieties for the garden, the market, and for canning are listed below. These varieties are named to show the range of variation and to indicate the leading groups or types, rather than to recommend these particular kinds. New varieties are continually supplanting the old. For the home garden.—Extra-early: Golden Bantam, an extra-early sort, has recently become very popular, on account of its productiveness, good flavor, and desirable size for table use. and because the kernels separate very easily from the cob; many plant it in succession so as to cover the entire season with this variety alone. Peep o'Day and Minnesota are other good extra-early varieties. Second-early: Early Crosby; Early Evergreen. Medium or standard season: Hickox Improved, Stowell Evergreen, White Evergreen. Late: Black Mexican, Country Gentleman. For market.—Extra-early: Cory (red cob), White Cob Cory, and Extra-Early Adams, which, though not a sweet corn, is largely grown for early use. This last- named variety is recommended in the South because of its comparative freedom from the attacks of the ear worm. Second-early: Shaker, Crosby, Early Champion; Early Adams also is extensively grown for market, though not a true sugar corn. Midseason and Late: Stowell Evergreen, Country Gentleman, Late Mammoth, Egyptian. For canning.— Stowell Evergreen is the standard variety for canning factories everywhere. Country Gentleman is also grown to a considerable extent for fancy canned corn. Other varieties that are used for canning include Early Evergreen, White Evergreen, Egyptian, Potter Excelsior, and Hickox Improved. Diseases and pests of sweet corn. The most widespread and destructive disease of corn in the United States is the smut produced by the parasitic smut-fungus, Ustilago Zeae. The sorghum-head smut, Ustilago Reiliana, also attacks maize. Smut causes most injury when it attacks the ears. The grains are transformed into a mass of dark-colored smut spores, and become exceedingly swollen and distorted out of all semblance to their normal outlines. Infection may take place at any growing point of the plant from early till late in the season, hence treatment of seed corn by fungicides is of no value as a remedy for corn smut. The destruction of smutted parts of the plants, and taking especial care that the smut does not become mixed with manure which is used for the corn crop, are measures which may be expected to lessen the prevalence of the disease. No remedy is known. Another disease of sweet corn in the United States is the bacterial blight caused by Pseudomonas Stewarlii. It has been found in New York, New Jersey, and Michigan, but thus far has been seriously destructive only on Long Island on early dwarf varieties of sweet corn. It is characterized by wilting and complete drying of the whole plant, as if affected by drought, except that the leaves do not roll up. The fibro-vascular bundles become distinctly yellow, and are very noticeable when the stalk is cut open. The disease attacks the plant at any period of growth, but is most destructive about the time the silk appears. No remedy is known. These two diseases are of the most economic importance in the United States. Two others of somewhat minor importance which deserve mention are rust and leaf blight. The leaf-blight fungus causes round, brownish, dead spots on the foliage. The maize rust, Puceinia sorghi, is found principally where rainfall is abundant. It is rather common throughout the corn- belt. The fungus is similar in nature to that which causes the rust of small grains. It cannot be controlled economically. Over 200 species of insects are known to be injurious to corn, either to some part of the growing plant or to the stored product. The corn-ear worm, known South as the cotton-boll worm, is especially injurious to sweet corn. It burrows in tender green corn, ruining the ear for either canning or market purposes. It is known to do serious damage as far north as western New York and central Iowa. Recent experiments in dust-spraying promise well. Spraying is done weekly, beginning when silks appear, using equal weight powdered lead arsenate and lime. Shallow fall plowing to kill pupae is a partial remedy. Wire-worms, northern corn-root worms, white grubs, and certain other grass insects attack corn plants. One of the best preventive measures is to plan the rotation so that corn does not immediately follow any cereal or grass crop.
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