Older Farmers Less Likely to Adopt Bt Corn

Purdue University study looks at Bacillus thuringiensis acceptance rates. Compiled by staff

Published on: Feb 20, 2006

You can't teach old farmers new tricks for controlling corn rootworms.

A Purdue University study found that as farmers approach late middle age they are less likely to plant corn that produces Bacillus thuringiensis (Bt), a protein that kills corn rootworms and European corn borer insects that feed on plant tissues.

The 2004 study, based on surveys and discussions with about 1,000 Indiana farmers who grew at least 200 acres of corn, also revealed farmers experienced in biotech crops are more likely to plant Bt corn hybrids, while some growers are less inclined to use Bt varieties because they find planting parts of their fields in non- Bt "refuge" corn a hassle.

As young farmers become more comfortable with biotechnology their adoption of genetically modified corn seed increases, says Corinne Alexander, a Purdue agricultural economist and the study's lead researcher. Older farmers who've never planted Bt hybrids aren't likely to start, however.

"What we found was age was a significant predictor in Bt corn adoption," Alexander says. "We found as producers get older and gain experience they are more likely to adopt Bt corn rootworm, but once they reach about age 48 they become less likely to adopt the technology."

The reasons, Alexander says, include time and profit potential. "For those farmers who are much closer to retirement, they receive a much smaller benefit from trying something new because they are only going to be farming for, say, another five or 10 years."

Indiana is an interesting case study for genetically modified corn adoption because the state has areas with severe, moderate and low corn rootworm problems, Alexander says.

The control dynamic changed in 2003 when Monsanto Corp. introduced a genetically modified corn resistant to corn rootworm. Seed with the corn rootworm Bt protein became widely available for growers in 2004. Despite the new insect resistance traits, only 21% of Indiana's corn was planted in biotech varieties in 2004 compared to 47% nationally, according to the USDA.

"Producers now have four options" in the corn rootworm fight, Alexander says. "They've got the no treat option. They've got the seed treatment option. They've got the soil insecticide option. And, now, they have the Bt corn rootworm option."

Refuges not a big deal

The Purdue study also found that preventing non-Bt corn from being pollinated by nearby Bt corn crops is a factor in producer adoption of the biotech seed. In addition, some farmers indicated that the extra effort in planting non-Bt refuges in or near their Bt corn crops discourages them from planting the corn rootworm-resistant seed.

"Farmers who are very concerned about pollen drift contaminating adjacent fields were significantly less likely to adopt Bt corn," Alexander says. "We also did a series of focus groups with producers. We asked them to agree or disagree with the statement, 'I will not plant a corn rootworm resistant variety because of the refuge requirement.' What was surprising was farmers who strongly agreed with the statement were also significantly less likely to adopt corn rootworm corn.

"What this indicates is that there's a small group that dislikes the refuge requirement and, because of that, they are not planting Bt crops. But by and large, producers says refuges were not that big a deal - just follow the rules, plant them and it doesn't take much extra time."

Farmers who plant Bt corn are required by the U.S. Environmental Protection Agency to plant 20% of their acreage within, around or adjacent to those biotech crops in non-Bt corn hybrids.

Among other findings in the Purdue study:

  • Growers who have planted genetically modified corn to control other corn pests would plant corn rootworm Bt hybrids, if given the opportunity. "We found that producers who had planted Bt corn that controls European corn borer in 2003 were significantly more likely to plant corn rootworm corn," Alexander says.
  • Europe's refusal to purchase many biotech grains - and the influence that decision has had on corn buyers within the United States - leaves some Indiana corn growers hesitant to plant corn rootworm-resistant hybrids. 

"If producers are thinking about planting corn rootworm-resistant corn, they will first want to make sure their buyer is willing to buy that corn," Alexander says. "You wouldn't want to plant corn rootworm corn without checking with them, because it doesn't so much matter what the European Union wants, what really matters is what your buyer wants."