For farmers in some areas of western Kentucky, southwestern corn borers are a real problem pest. Unfortunately, many producers weren't aware of the problem in 2001 until they began harvesting their grain.

Borers damage the corn and result in yield loss. Those difficulties coupled with fields planted with Bt corn looking unaffected by the pests has farmers considering using Bt corns for a majority of their crop.

Approximately 25 percent of the state's corn acres is planted in Bt corn varieties, said Ric Bessin, an entomologist with the University of Kentucky Cooperative Extension Service. Any increase in Bt corn production in 2002 will depend on a couple factors, he said. One will be whether a farmers' market will accept this type grain and the other will be the growing season. If the season is late and their market accepts it, then farmers will use it.

But before deciding to plant all their acreage in Bt corn, there are several factors farmers should evaluate, he said.

First, not all parts of western Kentucky were adversely affected by the southwestern corn borer, he said.

"Losses were primarily found in late-planted fields or fields that had been replanted," Bessin said. "Greater damage is common with the southwestern corn borer and it causes the worst damage in fields planted after May 1."

Studies at the UK Research and Education Center in Princeton during the past three seasons have found an economic advantage in using Bt corn only with later plantings, he said.

"While this technology is highly effective, it is not cheap," Bessin said. "Using a Bt hybrid will cost between $8 and $12 more an acre than a traditional hybrid."

So farmers need to consider whether their use of the hybrids makes economical sense.

"Generally, Bt corn will be economical for southwestern corn borer control when used for later plantings," he said.

How large a problem the insect will be in 2002 is unclear, Bessin said. It has been increasing and spreading across the state for the past eight years. If the winter is cold and wet enough, there may not be a problem with the insect this year.

If a farmer decides to use a Bt corn hybrid, he needs to leave a 20 to 30 percent refuge using non-Bt corn. The refuge is needed to ensure that corn borers don't develop a resistence to Bt corn, Bessin said.