Backyard Gardener: Sensational sweet corn
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Hello Mid-Ohio Valley farmers and gardeners! Hard to believe Memorial Day weekend is coming up. A salute to all of our military veterans and their families. Thank You!
Originally called Decoration Day, Memorial Day remembers all who have died in service of our great nation. On May 30th, 1868 over 5,000 people gathered to decorate the graves of 20,000 Union and Confederate soldiers buried at Arlington Cemetery. James Garfield, a Union major general during the Civil War, made a historic speech. Garfield was later elected as the 20th President of the United States.
This week let's talk about sweet corn. One of the most satisfying rewards of a vegetable garden in summer is to walk out and pick fresh sweet corn.
Sweet corn (Zea mays L. var. rugosa) is a popular choice for backyard gardeners in West Virginia. Sweet corn differs from field corn (also called dent corn) by a single gene called the sugary or su gene.
Corn (also referred to as maize) is native to America and has been cultivated in the New World for more than 4,000 years. It was an important food of the Incas, Aztecs, and Mayas of Mexico, as well as the cliff dwellers of the southwestern United States. Iroquois in Pennsylvania and New York grew a variety of sweet corn which turned blue as it matured.
The genetic ancestor of corn is a wild Mexican grass called teosinte. This small, skinny eared grass yielded just a dozen kernels wrapped inside a stone-hard casing. Selective breeding from this plant has resulted in the development of field corn, sweet corn, popcorn, and other types of maize used to feed people and livestock around the world.
Small plantings of sweet corn should be planted in blocks, a series of short rows rather than a single, long row because it is wind pollinated. This will boost production and result in improved ear quality through efficient pollination.
This crop is a monecious plant, which means it has a separate male and female flower on each stalk. The tassel is the male flower, which produces the pollen, and the ear is the female flower. Pollen from the tassel must be deposited on the silk of the ear for kernels to form. Ears not filled to the end are a sign of poor pollination or drought. Sweet corn typically produces one or two ears per plant.
When choosing varieties, there are dozens of choices based on the kernel color (white, yellow or bicolor), maturity, and the level of sugar content. Industry standard for bicolor sweet corn is 80 percent yellow kernels and 20 percent white kernels on each ear.
I know Silver Queen is a local favorite for white corn, but there are many improved white sugar enhanced and super sweet varieties out there that taste and store better. Maturity (days to harvest) for sweet corn is divided into early (less than 70 days), midseason (70 to 84 days), and late (more than 84 days).
Sweet corn may be divided into three distinct types according to its genetic background including normal sugary (SU), sugary enhanced (SE) and supersweet (SH2). Standard sweet corn varieties contain a "sugary gene" that is responsible for the sweetness and creamy texture of the kernels.
Today, these types of sweet corn are used primarily for processing. SU types are best suited to being harvested and eaten within a very short time because the ears retain their quality for only one or two days. Furthermore, standard varieties do not store well once harvested.
The sugar-enhanced (SE) varieties produce ears with tender kernels that have a higher sugar content than SU cultivars. The soft kernel pericarps make the corn tender and easy to chew. The harvest and storage periods of SE types are longer than for standard sweet corn.
Suggested sugar enhanced varieties include "Bodacious" (72 days, yellow), "Kandy Korn" (89 days, yellow), "Incredible" (83 days, yellow), "Delectable" (71 days, bicolor), "Luscious" (75 days, bicolor), "Silverado" (80 days, white) and "Argent" (86 days, white).
upersweet (SH2) or shrunken (wrinkled appearance of the dried kernels) sweet corn contains the SH2 gene, which give these high sugar types greater sweetness, a longer harvest window and a longer shelf life.
The conversion of sugar to starch is significantly reduced with SH2 varieties. Supersweet varieties are well suited for wholesale marketing where shelf life is important. Some recommended varieties include "Honey 'N Pearl" (78 days, bicolor) and "Illini Xtrasweet" (85 days, yellow).
However, supersweets do have some pitfalls. The seed coats are relatively thick, giving the kernels a tough or crunchy texture. The seeds are slow to germinate (especially in cool soils), may lack seedling vigor and are easily cross pollinated if planted to close to other types.
Sweet corn thrives in well-drained high organic matter soils. It can be grown on a wide ranges of soil types and a pH range of 5.8-6.8. It is a heavy feeder of nitrogen, so be ready to provide ample nutrients in a starter fertilizer (5-10-10) and side dress this crop at least once with a high nitrogen fertilizer (urea 46-0-0). Plant sweet corn 8-12 inches apart in rows with about three feet spaced between rows.
Seeds should be planted at about 1 inch depth. Sweet corn also may be planted in "hills" of 4 to 5 seeds approximately 3 inches apart. Hills should be spaced 30 inches apart with 30 to 36 inches between rows. When planting large amounts, a rate of 12 to 15 pounds of sweet corn seed per acre is recommended.
Keep in mind sweet corn is a warm weather crop, so the highest germination occurs when soil temperatures reach 60∂F. If you want to extend the harvest season, make more than one planting. A second planting should not be made until the first planting has three fully developed leaves. This may require more than three weeks in the early spring, but only two weeks later in the season.
Sweet corn has some pest issues which can be controlled with proper management. Corn earworm, Stewart's wilt and corn smut are some major issues. Mineral oil mixed with a Bt (Bacillus thuringiensis) insecticide (Dipel®) can be effective for controlling corn earworm. The oil is applied to the tip of the ear by hand on each silk about two days after the silk emerges from the ear. Applying the oil any earlier may reduce pollination.
Stewart's wilt is a bacterial disease spread by flea beetles and can be a problem if there is a large population of flea beetles. Many varieties are bred to resist this disease. Corn smut is a fungal disease most commonly seen as galls emerging from the ear. Many disease issues can be prevented with crop rotation and selecting resistant varieties.
Sweet corn is ready to harvest approximately 15 to 23 days after the silks emerge. Pick at the milk stage when the silks are brown and dry at the ear tip. The milk stage is when punctured with a thumbnail, the soft kernels produce a milky juice. In hot weather, sweet corn may remain in prime condition for only one or two days.
Over mature corn may become tough and doughy. Refrigerate immediately after harvest. Sweet corn does not store well so can or freeze your garden bounty as soon as possible. Contact me at the Wood County WVU Extension Office 304-424-1960 or e-mail me at jj.barrett@mail.wvu.edu with questions. Until next time, Good Luck and Happy Gardening!