In evaluating Bt corn hybrids in Alabama during 2011, there were perhaps more questions than answers, due primarily to low insect pressure.

“There are trends, and they show it might not pay off every year to plant a Bt corn hybrid here,” says Kathy Flanders, Auburn University Extension entomologist. “You have to pick the best hybrid for your field, the one that is best adapted to your area.”

Flanders discussed the use of Bt corn hybrids during the recent Central Alabama Corn Production Meeting, held in Autaugaville.

“In 2010, we had high corn borer populations in north Alabama and high caterpillar populations in south and central Alabama,” says Flanders. “Then, in 2011, we had low borer populations and lower caterpillar feeding, so that’s reflected in not seeing much difference in yields between the Bt corn and non-Bt corn this past year.”

All of the Bt corns being sold now are going to work on stalk borers, so if you farm in north Alabama or extreme southwest Alabama, where growers have problems with stalk borers, any of the currently available Bt corn varieties probably will help you, she says.

“In central Alabama, growers don’t have a problem with stalk borers, so the main problems will be with corn earworms and fall armyworms attacking the ear. So your yield increases probably will come from protecting the corn ears,” she says.

The newest kid on the block as far as Bt corn hybrids is the Agrisure Viptera trait, and it’s the only one that provides protection against corn earworms, says Flanders. In trials last year, hybrids with the Agrisure Viptera trait kept the corn ears very clean, she adds.

“Will these do you any good or help you with your yield?” asks Flanders. “Nothing was really significant in 2011. The ones with the more advanced Bt technology seem to give you some higher yields than if you don’t have Bt, but it wasn’t statistically different this past year.”

Trials are on-going to help determine if any of the Bt corn hybrids help with aflatoxin prevention, says Flanders. “This past year, under extreme drought stress, there were lower amounts of aflatoxin in some of the newer technologies. But aflatoxin is very variable from plot to plot, and we’ll have to look at this over several years. Caterpillar feeding and drought stress are only two things that affect aflatoxin. There are other things that increase the pressure.”