Is one of the most popular seed treatments in trouble?
By some accounts, the neonicotinoid class of insecticide seed treatments is a runaway success, planted on millions of corn and soybean acres every year to protect young plants.
Even so, its link to bee toxicity has many European countries banning neonics, with an Environmental Protection Agency (EPA) registration review in progress in the U.S.
“A very important part of [this process] is the benefits and alternatives analysis,” says Kelly Ballard, chemical review manager, EPA. “What we mean here is the benefits of the chemical to farmers and the economy as a whole. What would be the impact if we were to remove a chemical? How would that affect farmers and the economy? What types of alternatives would be used?”
The docket is enormous; the imidacloprid review alone includes more than 100 studies and 400,000 public comments. EPA plans to publish a follow-up assessment by December 2016. For more details, see John Dillard’s column on the next page.
Regardless of the outcome of EPA’s regulatory review, neonics are taking a hit. For example, Home Depot and Lowe’s each pledged to phase out products that contain neonics.
In addition, 12 Midwestern universities recently released a publication suggesting farmers overuse neonic seed treatments in soybeans. The researchers note neonic seed treatments offer soybean seedlings a three-week window of protection after planting that manages early season pests. However, the treatments’ usefulness is primarily confined to “targeted, high-risk situations” such as:
- Fields recently converted from CRP or grassland to soybeans.
- Fields with manure, green cover crops or weeds.
- Double-crop or specialty (food-grade or seed) soybean fields.
Other high-risk scenarios such as wireworms, white grubs and seedcorn maggots are uncommon where soybeans are grown. Adult bean leaf beetles cause cosmetic damage in newly emerged soybeans.
Unfortunately, these neonic seed treatments have little value controlling one of the biggest soybean pests—aphids. Neonic seed treatments are labeled for soybean aphid, but thresholds often occur weeks after the seed treatment’s window of protection ends. Natural predators such as Asian lady beetle and parasitic wasps often suppress early season infestations of soybean aphid.
Just like patients expect to know why a doctor wrote a particular prescription, farmers should expect to know why insecticidal seed treatments are recommended, says Chris DiFonzo, field crops entomologist with Michigan State University.
“I am not saying that neonic seed treatments aren’t justified—they just are not justified as often as they are used in soybeans,” she says. “I recognize it may not be easy to get seed treated with fungicide only, for example. Many dealers offer only combo products, or only guarantee seed treated with a full package of insecticide and fungicide. If growers want more choice in seed treatment in the future, the message is they have to speak up and be persistent.”
Not the Only Culprit
Neonicotinoids are often targeted for their possible role in Colony Collapse Disorder (CCD), a scourge that’s devastating bee populations and costing beekeepers billions. It’s not the only factor at play, however. Kim Kaplan, a public affairs specialist with USDA–Agricultural Research Service, says it’s likely a combination of factors that trigger CCD.
“These factors tend to overlap and interact with one another, which complicates issues,” she says.
Additional factors include: pathogens, improper nutrition, parasitic mites, sub-lethal doses of pesticides, migratory beekeeping (which can stress the hive) and climate change.