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Crop planter dust reduction may reduce pollinator threats

Entomologists battle potential restrictions on insecticide seed treatments

University entomologists continue their efforts to keep cotton farmers and other producers from losing effective insecticide seed treatments that some allege are threats to honey bees and other important pollinators.

Scott Stewart

The 2015 Beltwide Cotton Conference in San Antonio featured much information on insect control management. One issue centered on the buzz surrounding the use of neonicotinoid insecticides in Southern ag production.

“Neonicotinoids are very toxic to bees,” said Scott Stewart, University of Tennessee ag entomologist, adding that the issue of “colony collapse disorder (CCD)” is a major concern within the bee industry. A main cause of CCD is varroa mites, but most of the blame is on pesticides, especially neonicotinoids.

Nationally, some 143 million of the 442 million acres of cropland are treated with neonicotinoids. “They are widely used in the Mid-South,” Stewart said. “About 100 percent of our cotton and corn acres and a majority of our soybeans acres are treated with a neonicotinoid seed treatment.”

Research by Stewart and others in the region, the so-called “Bee Team” of university and USDA entomologists, is looking at the true impact of the insecticides, as well as better methods of preventing exposure of bees to neonicotinoids. That includes examining how to lower planter dust that may contain harmful amounts of the insecticide.

As far as actual concentrations to plants and fields, he said there is little, according to various Mid-South studies. “Our research finds that concentrations of neonicotinoids in nectar and pollinations is miniscule,” Stewart said. “I don’t think it’s a legitimate threat. The dust thing is the issue now, as far as seed treatments are concerned.”

He added that with tremendous pressure from environmental groups, activists and others against neonicotinoids, there “is a lot of defensive research.”

Popular vacuum planters, which use talcum graphite in the planting process, are emitting dust clouds, which often contain neonicotinoids, he said. “We know the dust clouds are moving out into wildflowers,” Stewart said. “It’s something we have to fix.

“We think with a little good engineering, we can avoid the dust cloud situation. I am confident there are better strides to use low drift compounds instead of talcum graphite. I’m confident John Deere and Case IH are building planters that don’t require talcum graphite.

Better filters

“We are seeing better filters for exhaust coming out of the back of these planters, so we are getting less exhaust of those compounds. Good engineering and some common sense can solve that problem.”

Further studies of the impact of the pesticides on pollinators involves closer exposure to test bee colonies to fields. Stewart said a portion of the research is trying to determine the pesticide dose available to bees in the pollen or the plant nectar to determine the risk to bees foraging in these field crops.

“We are putting hives out in ag areas to determine if bees in those areas are actually at a greater risk compared to bee hives in non-ag areas,” he said. “But time is not on our side.”

He was referring to new regulations either in place or being considered.

Stewart said new rules indicate that “every effort should be made to notify beekeepers no less than 48 hours prior to the time of the planned application so that the bees can be removed, covered or otherwise protected prior to spraying.”

Also, the application should be “made due to imminent threat of significant crop loss, and a documented determination consistent with an IPM plan or predetermined economic threshold is met.”

Ambiguity is a problem in the 48-hour regulation, Stewart said, because “we’re not sure if that applies” to beekeepers close-by or in the next county. This exemplifies the need for better communication between all parties involved, he said.

“We need to remain active on the issue. We need to make sure growers are aware of it,” he said. “We’re trying to develop a collaboration with all stakeholders, including beekeepers, to improve communication. We’re trying to avoid over-regulation that just doesn’t make sense.

“There is a lot of politics and activism involved and there are some legitimate concerns. We need to make sure we’re not causing unnecessary problems for pollinators and other honey bees.”

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