Over-planting of GM corn costing farmers billions, study finds
By Douglas Main
A new study adds to evidence that farmers in the US corn belt have over-planted a type of genetically modified (GM) corn, leading to estimated losses of more than $1 billion as the pests the corn was designed to repel have grown resistant over time.
The authors of the paper, published Thursday in the journal Science, said their findings supported a move toward a “more diversified” seed supply.
Known as Bt corn because it contains up to five toxins produced by a bacterium called Bacillus thuringiensis, the specialty corn is designed to express proteins that make the plant toxic to certain pests, including corn rootworm. More than 85% of corn planted in the US is the Bt variety, to which various insect pests are becoming resistant.
After examining rootworm crop damage data from 10 states over the period 2005-2016, the researchers determined that many farmers planted more GM corn than was considered necessary to address pest problems. Bt seeds typically carry a significant price premium.
The scientists found that planting Bt corn in certain eastern Corn Belt states provided “only marginal yield protection benefits,” benefits that appear to often be eclipsed by the higher costs for GM seed versus non-GM seed.