Sweet corn, field corn, cornmeal, popcorn-in its approximately 7,000-year history, corn in all its forms has never ceased to be in demand. Tastes may change, but corn has remained a staple worldwide.
Developed by Amerindian farmers from a Mexican wild grass plant, teosinte (Zea mexicana), hundreds of varieties of maize (Zea mays) were growing by the time Christopher Columbus arrived in the New World. (He's credited with introducing it to Europe.) Sweet corn is relatively modern, probably developed in the Andes around AD 1000. Until the introduction of ‘Golden Bantam' in 1902, most sweet corns were white-kernelled. The deep yellow kernels of ‘Golden Bantam' were an immediate hit, but the variety has since been eclipsed by sweeter, tastier hybrids with larger cobs and better resistance to insects and disease.
In 1950, scientists discovered the “supersweet” gene, which produces corn that contains little sucrose (the usual corn sugar) but lots of fructose (the sugar found in fruit), and retains that sweetness longer after harvesting. Supersweets-often referred to as s2 in seed catalogues-are too sensitive to cold soils to adapt well to most Canadian growing conditions.
However, it's the “sugar enhanced” corns, which first appeared in the 1960s, that have really caught on here. Sugar-enhanced corns are bred to have a very high sucrose content. Easy to grow, they produce huge cobs with tender, crunchy kernels and adapt fairly well to cold soil conditions. The first sugar-enhanced corns were bicoloured, the result of crossing yellow and white varieties, and these remain the most popular; they make up 65 per cent of the market.
“Three-way crosses” are hybrids that combine characteristics of supersweets and sugar-enhanced corns with excellent cold-hardiness. Although they are as sweet and tender as the sugar-enhanced corns, and much more tolerant of colder soils, they are more expensive and kernels often discolour during cooking.
Only a few cultivars of multicoloured sweet corns are available so far, such as ‘Indian Summer' (79 days), with yellow, white, red and purple kernels, and the similar ‘Triple Play'. ‘Sweet Scarlet' (85 days) is the first red sweet corn. So far, none are hardy enough for outdoor sowing except in southern Ontario and British Columbia, but could be started indoors in other areas.
Cobless corn (a bit of a misnomer, since there is a very slender cob) produces an unusual-looking, narrow bicolour corn with small but abundant sweet, tender kernels. Only one variety, ‘Sugar Finger' (78 days), is currently available. It's a bit slow to mature but I've had good results starting it indoors.
Several varieties of corn have had Bacillus thuringiensis genes bred in to make them insect-resistant, while others have been modified to make them more productive or resistant to herbicides. Collectively, these varieties are genetically modified organisms (“GMOs”). To avoid cross-contamination between GMO and non-GMO corns, do not plant non-GMO sweet corn across the road from a field of GMO corn.