Wednesday, July 9

How sweet it is!

Garden-grown sweet corn makes summer sizzle

Sweet corn has been one of America's favorite foods for centuries. Early selections included varieties like 'Stowell's Evergreen,' 'Country Gentleman' and the ever-popular 'Golden Bantam,' which was introduced by the W. Atlee Burpee Company back in 1902.

Thankfully, it's still possible to find seed for those and many other open-pollinated heirlooms. If you're lucky, you may find a few ears at farmers markets this season, but since these varieties are seldom commercially produced today, you will have to grow them yourself if you want to enjoy more than that.

Most people who grow sweet corn now grow modern varieties that incorporate specific genes to increase or enhance sugar content, kernel texture and shelf life. Though corn appears to be such a simple food, the science behind it is actually complex.

Sweet corn types
Sweet corn can be classified several different ways, including by kernel color (white, yellow or bicolor) or by the level of sugar content. Bicolor sweet corn has 80 percent yellow kernels and 20 percent white kernels on each ear. Originally, sweet corn was a standard or sugary type labeled as Su-1. Today, these types of sweet corn are used primarily for processing. The newer, sugar-enhanced (SE) varieties have a tender kernel and higher sugar content. SE sweet corn can be either heterozygous or homozygous. Heterozygous SE sweet corn is the offspring of an SE and Su-1 cross while homozygous SE sweet corn has both SE types as parents, making it the sweetest type of SE sweet corn.

Supersweet or "ultra/extra sweet" corn contains the SH2 gene, which is associated with slightly tougher kernels, an increased level of sweetness over SE types, plus a longer shelf life. The conversion of sugar to starch is significantly reduced with SH2 varieties and they are well suited for wholesale marketing where shelf life is important. In the home garden, though, avoid planting these supersweet varieties in cool soil (less than 60 degrees) because they lack germination vigor.

A new group of sweet corn varieties includes synergistic (SY), or triple-sweet types. These have about 75 percent of their kernels as SE sweet corn and 25 percent as super sweet. Synergistic types have higher sugar content than regular SE types and have excellent shelf life and kernel texture.

If you are planting sweet corn yourself, the different groups may need to be grown in separate parts of the garden to maintain consistent quality. You can do this by either planting the different types about 250 feet apart or by maintaining a 14-day difference between planting dates. Either choice will prevent cross-pollination.

Planting sweet corn
Sweet corn is a monecious plant, which means it has separate male and female flowers on each stalk. The tassel is the male flower -- it produces the pollen -- and the ear is the female flower. For kernels to form evenly on each ear, pollen from the tassel must be deposited on nearly every silk of the ear. (So during drought or silk 'clipping' by insects, you may notice poor kernel set.) Although bees are often seen collecting nectar and pollen from the tassels, sweet corn is actually wind pollinated.

For small plantings of sweet corn, a series of short rows about 24-36 inches apart (rather than a single, long row) will improve the chances for efficient pollination. Plant seeds one to two inches deep and eight to 12 inches apart. Or group three or four seeds closely together and separate the groupings three feet apart. This traditional Native American planting style works especially well when multi-cropping with pole beans and squash plants.

Sweet corn typically produces one or two ears per plant.

Sweet corn is sensitive to cool weather, so don't seed until soil temperatures reach at least 60 degrees. I've found that the most successful plantings for our area are in the first two weeks of May. These early plantings often avoid many insect pests that become established later in the growing season.

Pest management
Common insect pests of sweet corn include corn earworm, European corn borer, cutworms and corn rootworms. Some varieties of sweet corn have the Bt (Bacillus thuringiensis) protein genetically incorporated into them for protection against the corn earthworm and the European corn borer. They are labeled as Attribute(r) varieties. These varieties often require isolation from other types of sweet corn and destruction of the crop residue at the end of the harvest period in order to prevent the development of resistance. The Bt protein does not harm beneficial insects and is safe for consumption.

Mineral oil mixed with a Bt insecticide (Dipel(r)) can be affective for controlling corn earworm. Apply the oil by hand to the tip of the ear on each silk about two days after the silk emerges. Applying the oil earlier can reduce pollination. This technique is best for small plantings because it's very labor intensive.

Harvesting and handling
Sweet corn is ready to harvest about 20 days after the silks develop. When they are ripe, ears will have a dried silk, be full to the touch and have a tight, green husk. Harvest sweet corn when outdoor temperatures are low, preferably in the morning, and store it at 34 to 40 degrees for maximum quality. Most sweet corn has a shelf life of four to six days, but the supersweets will keep well for close to 10 days.

Corn is often overlooked as a home garden option, possibly because we see so much of it growing throughout our countryside. And, of course, there is often an abundant supply in our local supermarkets from mid-July into late September. There are, however, many rare and unusual varieties that make planting a small plot or two well worth the space in your garden.

Corn, zucchini, and tomato pie

Fresh corn and zucchini, seasoned with dill, bake underneath parmesan-crusted tomatoes to make a scrumptious entrée or side dish that can be served warm or at room temperature.

3 cups fresh sweet corn, cut from the cob
5 small zucchini, cut into matchstick pieces
2 teaspoons salt
1 teaspoon freshly ground black pepper
1 tablespoon fresh dill weed
2 tablespoons melted butter
3 to 4 vine-ripened tomatoes, cut into 1/2-inch slices
1/2 cup freshly grated Parmesan cheese
1/4 cup dry bread crumbs
2 tablespoons olive oil

Preheat oven to 375°F. In a 9 by 13-inch ovenproof baking dish, combine the corn, zucchini, 1 teaspoon salt, 1/2 teaspoon pepper, the dill and the melted butter, tossing to coat the vegetables. Cover the vegetables with the tomatoes. Sprinkle with the remaining salt and pepper.

In a small bowl, combine the cheese and the bread crumbs. Sprinkle the mixture over the tomatoes and drizzle with the olive oil. Bake for 30 minutes, or until the cheese is bubbling. Remove it from the oven, and let stand for 5 minutes before serving.

After completing culinary arts training at Joliet Junior College and working as executive chef at the Heartland Health Spa in Gilman, Alex Panozzo returned to his roots on the family vegetable farm in Limestone. He is active with the Kankakee Farmers' Market, the local agri-tourism industry and the University of Illinois Extension Master Gardener Program.