Transgenics Challenge System

Attention growers: More transgenic corn may equal more challenges.

That’s certainly the message Ohio growers are getting from state Extension experts. According to USDA, more than 40 percent of Ohio’s corn acreage was planted to transgenic hybrids in 2007, up from 26 percent the previous year. Peter Thomison, an Ohio State University Extension agronomist, says that number is expected to increase this year, and could play a role in the dynamics of corn planting.

"How growers will be approaching the way they plant corn this year will be more important than ever, given the increasing acres of transgenic corn," says Thomison.

Thomison says that corn growers face the challenge of pollen contamination and planting refuges when dealing with transgenic hybrids such as Bt (Bacillus thuringiensis) corn and Roundup Ready corn.

Given the close proximity of non-transgenic fields to potential transgenic fields, Thomison says that growers might have a difficult time ensuring that their non-transgenic corn remains that way.

"Go out and talk to neighbors and find out when they are planting. Stagger planting dates and plant hybrids of various maturities," recommends Thomison. "Take steps now to make sure those non-transgenic fields are isolated."

Another challenge growers face is adhering to the concept of planting a 20 percent refuge within a transgenic field, specifically when using Bt corn hybrids. Thomison says that planting a refuge is extremely important, especially with more and more growers jumping from non-transgenic hybrids right to triple-stack hybrids.

Guidelines also exist when planting a hybrid with stacked traits that contain both Bt types.

"Growers have two management approaches. The first choice is to plant separate refuges for each target pest," says Ron Hammond, an OSU Extension entomologist. "We recommend the second choice — the common refuge approach where corn without any Bt technology is planted. In this case, a 20 percent refuge must be planted within or adjacent to the transgenic field."

Hammond says that growers should consult their seed dealers for information regarding properly managing for transgenic corn hybrids, or for any additional IRM (insect resistant management) requirements related to single and stacked-trait corn hybrids.

Finally, Thomison says that growers planting no-till and reduced-tillage continuous corn should take steps to prevent uneven stands.
 

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