Corn has come a long way over the past 9,000 years
King Corn is a full member of the grass family. Outside of North America it is known as maize — more precisely, Zea mays. Corn in the English-speaking world outside of America really means wheat, barley, oats and even rye. In the many Bible references corn means small-grain cereals but not the Zea mays we call corn. That originated in Mexico, perhaps as long as 9,000 years ago, from a very small clubbed grasslike wild plant called teosinte. Indigenous Americans planted it mixed in with beans and squash.
Teosinte, a wild grass-like plant, is native to Mexico and Central America. It hardly resembles modern-day corn cobs due to its small ears and tough outer covering. This, though, is the plant ancient farmers selected and reselected over thousands of years via natural mutations to give us the present-day distinctive corn varieties. We now have thousands of corn varieties, from sweet corn types and popcorns, to field corn with grain that comes in very many colours from blue and red to black and purple, down to the commonly grown orange, yellow and white grain types.
Corn as we now grow it in its very many types is entirely dependent on plant breeders, farmers and horticulturalists for its propagation. Corn is now the No. 1 food/feed crop grown in the world, passing potatoes, wheat and even rice. Corn is primarily used as an animal feed grain, hay baled or used for silage production. The high-sugar varieties are used for human consumption, whereas field corn is primarily used as animal feed. Corn is processed into starch, corn syrup, oil and feedstock for alcoholic beverages or biofuels.
Read Also
Patience required for winter cereals in the springtime
Manitoba’s weather in the first half of April wasn’t warm enough for winter wheat and fall rye to consistently grow
In Canada, corn is a warm-season crop, growing its best in the hotter areas of Ontario and parts of Quebec with the higher available heat units. Plant breeders have developed more cold-tolerant varieties of corn in the past few decades, allowing it to grow successfully as grain or silage corn, particularly in the warmer areas of the Prairies. Manitoba, in recent years, has grown around a half a million acres of grain corn (498,900 harvested acres in 2024), followed by relatively little in grain corn production in either Saskatchewan or Alberta. Yields of grain corn in Manitoba average over 100 bushels and upward, resulting in 1.8 million metric tonnes annually. Ontario and Quebec are by far the biggest corn growers, with Ontario’s two million to three million acres resulting in 9.5 million tonnes for 60 per cent of Canada’s corn production. Quebec follows with almost a million acres and 3.4 million tonnes of grain.
Corn yields in the U.S., especially under irrigation and high fertility, can frequently yield 200-300 bushels per acre or more. The current record yield for corn, at Charles City, Virginia, is given exactly as 623.8439 bushels per acre. To achieve such a phenomenal yield, the crop is given all of the macro- and micronutrients needed and regularly irrigated. There is no problem with heat units needed for grain maturation in Virginia — but there is one vital limiting factor needed to achieve this yield.
Did you guess? It’s carbon dioxide. In mid-July an excellent stand of corn supplied with a fully adequate supply of crop nutrients (minerals) at midday may be critically short of carbon dioxide. There are only 422 parts per million (p.p.m.) of CO2 in the atmosphere, up from 250 p.p.m. in past years. On a hot midday, a C4 corn plant in full sun may be well supplied with water and plentiful nutrients but it cannot get enough CO2 for its sugar formation. The record-yield growers ensure the corn cropland is loaded with masses of crop residues. These crop residues in the warm moist soil are producing huge amounts of CO2 as a result of the soil microbes feeding on this residue. This CO2 moves upward into the crop canopy, where it’s captured by the corn leaves. Unlike those of soybeans or wheat, corn’s leaves have the ability to capture and store this extra CO2. Under good growing conditions, perhaps with a light breeze for distribution, this extra CO2 may be rapidly converted via photosynthesis into sugar.
Silage corn acres are on the increase on the Prairies, with around 100,000 silage corn acres in both Manitoba and Saskatchewan and more than 600,000 acres in Alberta making up for that province’s very modest grain corn acreage.
Corn, the world’s largest grain crop worldwide, amounts to about 1.2 billion tonnes. Of this amount some 360 million tonnes are produced in the U.S. for a 31 per cent world share. China is second with 260 million, for over 22 per cent of the total corn crop. Brazil, Argentina and Ukraine are major players accounting for a further 17 per cent. Very many other counties grow the remaining millions of tonnes of corn making up the annual total.
In high-production areas, corn is invariably grown as a hybrid. Seed corn is the offspring of two pure lines of corn referred to as inbred parents. Hybrid seed yields more grain than the parent inbred lines — and much better than open-pollinated varieties. Seed from the female (male sterile) parent is harvested for seed, whereas the male pollen rows are destroyed after pollination or harvested separately.
Enemies
Corn, like other Prairie-grown crops, suffers from many diseases and insect pests. The diseases run from the bacterial, such as Stewart’s wilt, to a variety of fungal diseases. Such diseases include common and head smuts, southern and northern leaf blights, stalk rots, ear rots, rusts, anthracnose and downy mildew. Quite the collection!
The most destructive disease of all in Canada is pink or red ear rot, or Gibberella mould. This fungus, Gibberella zeae, can destroy whole grain cobs and can only be stopped after harvest in the grain if it’s dried down to 15 per cent moisture or less, ASAP.
One complaint I have is that my fellow plant disease specialists do an excellent job of confusing corn-growing farmers. Pink mould of corn, Gibberella zeae, is the exact same fungus as Fusarium graminearum. Gibberella zeae is just the sexual stage of Fusarium graminearum. So, put another way, pink mould in corn is the exact same fungus that causes fusarium head blight (FHB) in wheat, barley and other small grains.
Whether on corn or other small grains, like wheat, this fungus produces toxins in the grain, such as DON (deoxynivalenol) and a range of other toxins that are extremely destructive to pigs. Any DON, for example, of greater that 0.5 p.p.m. in feed grain is unacceptable as hog feed. Cattle can tolerate levels of up to eight p.p.m.
When I was a plant disease specialist in Ontario, many years ago, a couple of wet summers in Ontario corn acres resulted in major outbreaks of pink mould in the harvested corn. It became a feed disaster for the Ontario hog industry. So, consider that if you grow corn after wheat or vice versa and have a wet summer or fall, be prepared for possible outbreaks of this disease in either crop in such a rotation.
Final thought: “In the course of my life I have often had to eat my words and I must confess that I have always found it a wholesome diet.” – Winston Churchill
Ieuan Evans is a forensic plant pathologist based in Edmonton, Alta. He can be reached at dr.irevans@gmail.com.
Source: producer.com