WOOSTER, Ohio – The use of transgenic corn hybrids could increase significantly in Ohio next year, due to rising corn rootworm problems and lower product costs compared to traditional hybrid packages.
Increase. According to the most recent USDA survey regarding the adoption of crops that carry transgenic traits, only 18 percent of the total corn acreage in Ohio in 2005 was transgenic corn. However, that number has increased from 9 percent in 2003 and is anticipated to continue growing next year.
Transgenics is the science of introducing a gene from one organism or plant into the genome of another organism or plant.
Crop production examples of transgenics include different types of Bt corn to control European corn borer and rootworm, and Round-Up Ready corn and soybeans for enhanced weed control.
Ron Hammond, an Ohio State University research entomologist with the Ohio Agricultural Research and Development Center, said one of the reasons for the increased interest in transgenic corn is the problem growers encountered this growing season with first-year corn rootworm, especially in continuous corn production.
“This year we have seen some of the heaviest pressure from rootworm we have seen in 10 years, both from root injury and from adults feeding on the silks,” said Hammond.
“Not only did we see increased pressure from the western corn rootworm in corn fields, but we also saw increased numbers from the first-year corn rootworm variant in soybeans. We are not sure if this is a fluke or if this will be repeated next year. This is very unusual for Ohio.”
Sampling. Western corn rootworm variant sampling in 86 soybean fields covering 25 counties was conducted throughout western Ohio. Over 20 percent of the fields sampled had an average rating of five or more beetles per trap per day, the highest assessment given in rootworm sampling.
Such a rating indicates a potential problem with rootworm in the field the following year.
“Corn rootworm is probably the most damaging corn pest in the Midwest,” said Hammond. “If you have a good population of rootworms, you will get a straight yield reduction from that feeding. You lose one root node and there’s an immediate yield loss. More than one node lost and it doesn’t take much of a wind to knock that corn to the ground. Plus you get poor kernel set if you’ve got adults feeding on the silks.”
Good choice. Apart from using insecticides and seed treatments to control corn rootworm, Bt-rootworm hybrids are an option, and with seed of transgenic hybrids getting cheaper, using transgenics is becoming a more attractive choice.
“The adoption of transgenic corn is probably being driven more by the market than agronomics,” said Peter Thomison, an Ohio State University Extension agronomist. “Seed companies are offering these products at very attractive prices so a lot of growers see the benefit of spending a few more dollars on transgenic hybrids than to buy their current traditional hybrid.”
Hybrids. Thomison said he sees more Ohio growers planting stacked transgenic hybrids in 2007 – those that carry Round-Up Ready, Bt-corn borer and Bt-rootworm traits.
While he acknowledges the benefits of transgenic hybrids, Thomison is encouraging growers to choose hybrids based on overall performance, that is, plant hybrids that exhibit high yield potential across a range of different environmental conditions.
Transgenic corn is, however, desirable under situations where growers may be facing problems with first-year rootworm.
“It’s outstanding technology if used properly,” said Hammond. “It’s a nice alternative to soil insecticides.”
Recommendations. Hammond stresses if growers do use transgenic hybrids, follow the requirements of planting 80 percent transgenic and 20 percent nontransgenic to prevent the pest from developing resistance.
Additionally, Hammond recommends growers plant untreated check strips to determine the level of corn rootworm severity the following year.
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