Corn, Sweet

Sweet Corn

Seed companies have offered an explosion of new sweet corn hybrids in recent years. Sweet corn varieties can be divided into three broad groups: normal sweets, sugary enhanced sweets, and super sweets. Within the sugary enhanced group there are two types: those with 100 percent of the kernels being sugary and those with about 25 percent of the kernels being sugary. Both the normal sweets and the sugary enhanced are excellent types for gardens because seeds are normal in size and germinate well.

Super sweet seeds are small, and conditions must be ideal for good germination. Super sweet seedlings are slower to establish than the normal and sugary enhanced types. The super sweets have a sugar content that is two to three times higher than that of normal sweet corn and a slow conversion rate of sugar to starch. Therefore, super sweets hold up well on plants and in the refrigerator.

Both the normal sweet and the sugary enhanced sweet corns have fairly rapid rates of conversion of sugar to starch, but these sweet corns also have a creamy texture, while super sweets are more crisp and watery.

In addition to differences in sugar content, sweet corn also comes in different colors: yellow, white, and bicolor (yellow and white kernels on the same ear).

Sweet corns also are divided into varieties that mature early (65 to 70 days), midseason (70 to 80 days), and late (80 or more days). Most early varieties are better adapted to the northern states and do not make satisfactory growth or ear size in the south.

For an ear of corn to develop properly, corn pollen from the tassel at the top of the plant must fall to the silks of the ear located about halfway up the stalk. Plant several short rows, rather than one or two long rows, for better pollination. Better pollination means fuller ears. Hot, dry conditions during pollination result in missing kernels, small ears, and poor development of ear tips. A water shortage, signaled by visible wilting (rolling of the leaves), at the time of silk emergence results in reduced yields and quality.

When different varieties of sweet corn planted close together silk and tassel at the same time, crosspollination can occur by wind-blown pollen. This may result in something as simple as yellow kernels scattered in the ears of white corn; but more important is the reduction in quality when super sweet corns are pollinated by any other type of sweet corn. Therefore, isolate the super sweets from other sweet corns by time of planting so that they silk and tassel at different times; or isolate them by a distance greater than the pollen is carried by the wind. If popcorn and field corn pollinate any type of sweet corn, they will destroy its eating quality.

Soil fertility problems frequently cause low yields in sweet corn. If soils are cold and wet during early planting, deficiencies of nitrogen and phosphorus will occur. Small ears at harvest indicate low fertility, and poorly filled ear tips indicate low nitrogen, phosphorus, or potassium.

Corn earworms are the most serious sweet corn pests, although chinch bugs, flea beetles, blister beetles, and armyworms also cause serious damage. As soon as silks appear, spray or dust to control earworms. Continue to apply insecticide on a 3- to 4-day schedule until silks are brown and dry.

Sweet corn is ready to harvest about 20 days after the first silks appear. The ear should feel full, the kernels should be plump, and the juice should be milky in the normal and sugary enhanced types.

Birds are a problem at planting time and at harvest time. They pull seedlings from the soil to feed on the kernels and also feed on the ears as they approach maturity. Problems with animals, such as raccoons and squirrels, feeding on sweet corn as it matures are difficult to prevent. You can prevent some damage by using a 2-strand electric fence around the garden. Place one wire about 4 inches aboveground and the other at about 12 inches. The electric fence should be in operation well before corn approaches maturity.

Varieties

Normal type

• Jubilee—yellow; large ear; white silk; late.
• Merit—yellow; tolerant to high temperatures and drought; large, heavy ears; smut resistant; sometimes called silkless because silks come off ears easily; midseason to late.
• Silver Queen—white; exceptional quality; late.
• Sweet G-90—bicolor; very tender and sweet; 75 days.

Sugary Enhanced (se)

• Bodacious—homozygous se; yellow; early (75 days); medium-sized ear; excellent eating.
• Calico Belle—bicolor; homozygous se; midseason; medium-sized ear; excellent eating; good yields.
• Incredible—yellow; an improved Miracle; good husk protection and tip fill; 100 percent se; late.
• Miracle—yellow; excellent flavor; tender kernels; large ears; midseason.
• Platinum Lady—white; excellent flavor; purple color in stalks and husks; early to midseason.
• Snowbelle—white; creamy texture; 1 week earlier than Silver Queen.
• Tendertreat–yellow; excellent flavor and tender; purple color in stalks and husks; tall plants; late.

Super Sweet (sh2)

• How Sweet It Is—white; 8-inch ears; late; requires isolation; 88 days; AAS 1986.
• Summer Sweet 7210—yellow; 8-inch ears; midseason; requires isolation; 78 days.