sealPurdue News

March 14, 1997

To Bt or not to Bt

WEST LAFAYETTE, Ind. -- Should Midwestern farmers plant Bt corn to stop European corn borers?

This year, according to Purdue University entomologist Larry Bledsoe, the answer is a definite "Maybe."

After compiling and analyzing data from Bt corn trials in Illinois, Iowa, Kansas, Kentucky, Missouri, Nebraska, North Carolina, Ohio and Pennsylvania, Bledsoe concluded that Bt corn hybrids significantly reduce damage caused by European corn borers. But whether they'll yield better than standard varieties in a farmer's field depends upon the competition.

Bt corn hybrids have been genetically altered to contain a crystalline protein that kills young caterpillars feeding on it. The protein -- Bacillus thuringiensis, commonly known as "Bt" -- is produced in the plant's tissue, where European corn borers feed.

"Resistance to European corn borer is important, but it's not everything," Bledsoe cautioned. "You also have to consider such things as soil, climate, disease resistance, drought tolerance, germination and tolerance to compaction. You might get higher yields with a non-Bt hybrid that's better adapted to your area."

If you want to use Bt corn, select a hybrid that has the complete package of characteristics you need, including yield potential, disease resistance and local adaptability, Bledsoe said. Corn borers aside, your Bt hybrid should yield as much as the standard hybrids that you currently plant.

If none of the Bt corn hybrids out there meets those requirements, Purdue entomologist Rich Edwards advised that you re-evaluate the situation in a year or two.

"We suspect that as new Bt varieties come on the market, they will have more of the high-yielding and weather-tolerant characteristics of the standard varieties," Edwards said.

Even then, however, remember that you'll pay for the insurance Bt corn gives against European corn borer damage.

"Because the companies that developed these Bt varieties are charging a premium to recover development costs, producers need to closely evaluate those hybrids to determine if the premium that they're paying for this technology is worth it," Edwards said.

It could well be worth the money. But the only way to know for sure is to run your own field trials, Bledsoe said. He recommended that producers who grow Bt corn also grow their normal high-yielding varieties and compare the damage from corn borers as well as the yields. After that, he said, producers can decide if the price is worth it.

To help farmers evaluate the new hybrids, the Purdue entomologists will run Indiana field trials on Bt corn hybrids at several locations this year.

Sources: Larry Bledsoe, (765) 494-8324; e-mail,
Rich Edwards, (765) 494-4562; e-mail,
Writer: Rebecca J. Goetz, (765) 494-0461; e-mail,
Purdue News Service: (765) 494-2096; e-mail,

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