Sweet Corn Hybrids Make Strides

May 31, 2010 08:17 AM
There's a revolution going on down in the sweet corn patch. Higher sugar contents and hybrids that hold eating quality up to a week longer are already making their way to the dinner plate. So are varieties genetically enhanced with Bacillus thuringiensis (Bt) (goodbye gooey, gluttonous earworms). Herbicide resistance is on its way too.
Consummate sweet corn lover and University of Illinois plant pathologist Snook Pataky says the arrival of high quality shrunken-2 (sh2) hybrids have been the big news in sweet corn over the past few years. "These are hybrids which combine the sh2 endosperm mutation (supersweet) with other sweet corn mutants (sugary or sugary enhancer) to result in quality that is far superior to the old standard supersweet hybrids,” says Pataky.

Sometimes marketed as extra-tender or augmented hybrids, these hybrids extend their flavor by slowing simple sugar conversion. A thinner pericarp delivers more tenderness and the hybrids typically pump out more kernels per pound.
Discovery of resistance genes is also helping corn breeders produce hybrids that fight back against rust, northern leaf blight, Stewart's wilt and maize dwarf mosaic (MDM).
Want to get the bugs out? Rogers brand, Syngenta's vegetable seed division, is currently the sole industry provider of genetically enhanced sweet corn hybrids with protection against damage by European corn borer, corn earworm and fall army worm. Mark Mason, Syngenta Global Crop Unit Manager, says insect protected hybrids are sold under the Attribute brand and contain the same Bt protein common in commercial field corn.
"Sweet corn containing the Bt gene is not accepted for export or processing, but has been commonly used for fresh market purposes for the past 12 years,” says Mason. "Growers must still monitor insects in high pressure situations, but the protection generally reduces use of chemical pesticides by as much as 50%.”
Because corn is wind pollinated, shrunken (sh2) and sugary enhanced (se) types should be isolated from all other types of corn to maintain eating quality. That typically means a 250 ft. buffer, separated by an effective wind break, or a 10 to 14 days difference in maturity from field corn.
Don't expect to find GM sweet corn traits in the packets at your local garden store though. Growers interested in Bt-enhanced sweet corn need to contact Syngenta seed dealers. Mason says the company is working to stack current resistance with herbicide resistance and their new Agrisure Viptera trait, a novel vegetative protein and new mode of action protecting against lepidopteron pests.
A native trait led to the company's TruStart hybrid lineup, a new generation of supersweet hybrids with improved emergence characteristics. "We're also working to produce hybrids with native trait herbicide tolerance,” says Mason.
Within the next few years, Monsanto Company intends to commercialize an herbicide-tolerant, insect-protected sweet corn in the United States. Danielle Stuart, Monsanto communications, says the Roundup Ready product will contain two insect resistant modes of action. "The Seminis sweet corn program already has a full line up of quality varieties,” says Stuart. "We are using advanced breeding techniques to develop new varieties with improved flavor and eating quality, increased disease resistance, better standability, improved husk packages and better shipping characteristics,” she adds.          
Now if there were only genetic raccoon resistance. "They are one of our biggest pests,” Mason says of the masked bandits. "They seem to know where the first corn is and later, they become more discriminating and head for the very sweetest and best ears in the field.”
Pataky concurs. "You could almost use them as the selection index in a breeding nursery if it were not for the ear damage,” he notes. The electric fence and perhaps nighttime vigilance remain your best line of defense.


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