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Seed Treatment Encourages Resistance

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Planters are rolling out to get the next crop in the ground. When they do, they will put seed in that often has treatment to protect against fungus or bugs.

Neonicotinoids have been a popular way to stop insects from getting to the seed and young plants. But they might be over used. They are a useful pesticide because they are put directly in the soil and it seemed as though they did not hurt the good insects like pollinators.

But according to Iowa State professor Dr. Mary Harris, new studies have researchers like her asking even more questions.

For one, the EPA has put out an opinion on neonicotiniod use on soybeans. Saying it’s mostly useful for southeastern U.S. farms.

Harris points out, “We don’t have the same insect pressure here, the same insects that attack soybeans. So, use on soybean seeds, except in these areas in the southeast is really unnecessary.”

Harris says a similar opinion has not come out yet on corn.

Neonicotinoids have a three year persistence in the soil and Harris says they have been used since 2004.

She points out the ISU Extension and Iowa Natural Resource Conservation Service, which want to highlight Integrated Pest Management (IPM), which turns pest control from pre-emptive to responsive. That requires scouting and data but it makes pesticides more cost-effective because it’s put where it’s needed.

Harris says, “You’ve got a toolbox, the different methods of pest control that you utilize. And you utilize all of them in an integrated manner. And one of the cornerstones of IPM is to not overuse any one particular insecticide because ultimately, insects develop resistance.”

According to the U.S. Geological Survey, neonicotinoids have now extended off the farm. Traces have been found in urban streams, though the amounts are very small and don’t reach the Environmental Protection Agency criteria of being a problem to wildlife. On top of that they are classified as not likely carcinogenic to humans.

Neonicotinoids are built to be like nicotine, which is what you find in tobacco, and because they target specific receptors on insects, they don’t hurt mammals.

Harris’ area of study shows that dust from neonicotinoids are spread around the environment. While they aren’t sure if that affects pollinators like bees, they know it gets on the pollen that bees bring back to feed their young. Researchers don’t know if that hurts bees or if insects are developing resistance already.

Harris says more study is needed, but a way to ease concerns is to look at where the chemicals are needed, “Instead of planting your whole field where you don’t have the pests, but you’ve got the pests in these spots, better to only use the seed treatment there, and again, it’s not just for saving money, but it’s for saving the efficacy of the chemical itself.”

Harris adds that in a time of low commodity prices, farmers may want to look at how expensive treatments like neonicotinoids are.