What's Cropping Up? Blog

Articles from the bi-monthly Cornell Field Crops newsletter

Statewide Corn Trials Underway: Do We Need Neonicotinoid Seed Treatments in NY?

By Jaime Cummings, NYS Integrated Pest Management

No-till corn field

(No-till corn field, photo by Ken Wise, NYS IPM)

Most corn and soybean growers in New York plant seed treated with insecticides.  But are those treatments really needed in every field?  The recent scrutiny on neonicotinoids (aka: neonics) causing harm to pollinators has brought this question to the forefront.  Given all the negative attention that neonicotinoid have received in the media in recent years regarding pollinator health, it’s no surprise that they are on the chopping block in some NY legislative bills.  These bills follow similar bans on neonics that have already taken place in Europe and Canada.  Neonics have a bad reputation as having negative effects on bee health.  Think about all the news you’ve seen or heard about the “bee-pocalypse”.  And, it’s true that they can be lethal to bees and other beneficial pollinators, especially if applied to crops at incorrect timings or under the wrong conditions.  They are insecticides, after all, and they are effective at killing insects, the good ones and the bad ones.  But, let’s not forget about the bad ones they are intended to target to help farmers raise healthy and productive crops to feed livestock and all of us.  It’s important that we consider both the positive and negative effects of these seed treatments when determining an overall need and value in our agricultural systems.

Hundreds of dead bees near a bee colony, believed to have been exposed to neonics

Hundreds of dead bees near a bee colony, believed to have been exposed to neonics (Photo courtesy of D. Schuit)

Neonic insecticides are used in many cropping systems, from fruits and vegetables to ornamentals to corn and soybeans to protect against some troubling pests.  Neonics are available as seed treatments, soil drenches or foliar sprays to various crops, depending on the target pests and formulation of the products.  And farmers everywhere have been using them for years, often as part of an integrated pest management program, to help minimize losses to some destructive pests.  They were so widely adopted because they are effective pest management tools and because they were perceived as having a reduced overall negative impact on the environment and human health compared to many of the older insecticide chemistries, such as the organophosphates.  But then it became apparent that these neonics, though safer for human health than many other insecticides, were taking a toll on beneficial insects, especially our bees that we rely on for pollinating many of our important food crops.  And we need to pay attention to that issue and determine ways to mitigate those risks.

Seedcorn maggots feeding on a corn seed.

Seedcorn maggots feeding on a corn seed. (Photo courtesy of J. Kalisch, University of Nebraska)

As mentioned above, neonics are used in various ways in many cropping systems.  But their use as corn and soybean seed treatments has received a lot of attention because of the known potential for the neonic seed treatments to drift off-target as dust during planting.  Because corn and soybeans cover such vast acreage in NY and across the country, mitigating these risks could potentially have a large impact on reducing bee mortality.  Therefore, these seed treatments seem a likely, and potentially easy target for negative attention when folks start looking to reduce overall neonic usage.  In response, the seed and seed treatment industries working with the EPA, USDA and other organizations started looking into ways that they could reduce the negative impacts that neonic treated corn and soybean seed could have on bees.  In 2013, the EPA held a Pollinator Summit to focus on reducing exposure to dust from treated seed.  Much research went into this focus group with collaborations between industry, academia and governmental regulatory agencies to address the off-target movement of dust from planting neonic treated seeds.  I encourage you to read all the details for yourself regarding what they did and what they discovered in the Dust Focus Group and the Seed Treatment Group.  For the sake of this article, I will briefly summarize their findings, conclusions and recommendations:

  1. Start with clean, quality seed with minimal dust to begin with – many major seed companies have high standards for starting with clean seed which allows seed coating to better adhere, resulting in less dust.
  2. Use improved polymers for adhering treatments to seed coats: seed coating technologies have improved dramatically over the years, meaning that less active ingredient ‘falls off’ the seed coat.
  3. Use bee-safe seed lubricants:  this minimizes the dust moving to off-target plants. New seed coating polymers and polyethylene wax lubricants for talc replacement can result in 90% total dust reduction and 65% active ingredient reduction in the dust.
  4. Eliminate flowering weeds in and around fields prior to planting – this reduces the number of flowers that may accidentally have neonic dust that bees may forage on.  The goal of many field crop growers is to ‘start clean’ meaning that they often try to minimize or eliminate competition from weeds prior to planting.
  5. Be aware of wind speed and wind direction at time of planting – be a good neighbor. Avoid planting on the windiest days (when possible) and be aware of nearby bee colonies and wind direction.  There are actually apps available to connect bee keepers with farmers to raise awareness of pesticide applications and locations of bee colonies.
  6. Re-direct the exhaust flow of vacuum planters downward to minimize off-target movement of dust.  Simple modifications can be made to some planters to re-direct the flow of the exhaust down toward the soil, which can significantly reduce dust movement.  (Many planters don’t exhaust, and most air seeders already exhaust downward).
  7. Follow labeling instructions for handing, storage, planting and disposal of treated seed and containers.
EPA Website Screenshot on Pollinator Protection

https://www.epa.gov/pollinator-protection/2013-summit-reducing-exposure-dust-treated-seed

The findings, improvements and recommendations from this summit can greatly decrease the risk of negative effects of dust from neonic seed treatments on pollinators.  However, some people are also concerned about neonics that might move through soil or water showing up in water and non-target plants. Because of these issues, neonic seed treatments might still be banned on corn and soybean in NY, so growers are concerned.

Neonic seed treatments come standard in just about every bag of corn and soybean seed planted.  Some say we do need them, others say we don’t.  If we look back in history a few decades, before the neonic seed treatments became available, farmers in NY struggled with early season pests like the seedcorn maggot, which can significantly reduce stand counts (and yields) under high pest pressure.  The seedcorn maggot is favored by situations with actively decomposing organic matter, such as manure applications and terminated cover crops.  Both of these situations are quite common in NY corn and soybean production systems.  But, since the neonic seed treatments became so widely used, the seedcorn maggot issues have decreased dramatically, and possibly faded from memory.

Skips in a corn row caused by seedcorn maggots eating the corn seed.

Skips in a corn row caused by seedcorn maggots eating the corn seed. (Image courtesy of T. Baute, OMAFRA)

But it still begs the question:  Do we have pest pressure that warrants neonic seed treatments on the vast majority of our acres of corn and soybean every year?  That is a good question.  From an integrated management perspective, it’s never recommended to rely so heavily on one tool in the tool box for as long as we have with these neonics.  We know that our insect pests can develop resistance to insecticides, just like weeds develop resistance to herbicides.  There is also some evidence from various academic studies showing that the neonic seed treatments can negatively impact predatory insects, such as ground beetles, and other beneficial insects that serve as natural biological control of some of our other pests, such as slugs.

Given those reasons, it seems like it might be a good idea to reduce our dependence on neonic seed treatments, and only use them in situations where we know we need them, right?  But, on the other hand, it’s important to keep in mind that, for now at least, it’s not easy to buy corn or soybean seed without a neonic as part of the seed treatment package.  It’s very efficient and economical for the seed industry to include these standard treatments on their seed, and it’s also important for their liability for the guarantees they may offer farmers who purchase their seed.  Not to mention that it’s not easy to anticipate when and where we need the neonic seed treatments each year.  Sure, we know that fields with a history of manure and/or cover crops may be more likely to have seedcorn maggot issues, but there’s no guarantee they won’t also show up in a clean, tilled field.  And, once the crop is planted, it’s too late to scout and determine whether or not the seedcorn maggots are going to be a problem.  This unpredictability is why the neonics are used as an ‘insurance plan’ against these sort of pests.

This conundrum is why this is such a highly polarizing debate, and why the proposed legislative bans have some farmers riled up.  It’s not that farmers want to use or pay for any more pesticides than they need, but the risk can be too high for their bottom line to just stop using them altogether.  We need local research to back up any claims for or against the use of insecticidal seed treatments in corn and soybean production, and specifically the need for neonics.  Much of the research from other states shows that they may not be necessary after all, because they don’t seem to cause a yield benefit.  But, upon closer inspection of some of those results, many of those trials didn’t have measurable insect pest pressure to produce meaningful comparisons of treatments.  And, many of the areas where those trials were conducted do not have the same practices with high organic inputs from manure and cover crops that many NY farms do.

Seedcorn maggot damage to soybean

Seedcorn maggot damage to soybean (Photo courtesy of University of Minnesota)

So, it’s complicated.  A great deal of pollinator risk research is being conducted at Cornell, including a risk assessment of neonic use.  The results of that assessment could influence the future of legislation on the availability or restriction of these products.  We know the dust from the neonic seed treatments poses a potential threat to pollinators (especially bees).  But we also know from the EPA pollinator summit that there are ways to mitigate those risks through improved seed coating and seed lubricant technologies, which have been widely implemented.  However, we still don’t know if there are other risks from these seed treatments, and we need more concrete evidence to know whether or not these neonic seed treatments are really necessary in such a large percentage of our NY corn and soybean acreage.

That’s why we decided earlier this spring to coordinate five statewide large-scale, on-farm trials with NYS IPM and Cornell Cooperative Extension specialists to try to evaluate the effect of these neonic seed treatments on 1) plant populations, 2) yield, and 3) how they compare to the anthranilic diamide seed treatments which could potentially replace them if the neonics are banned.  These corn silage trials will be located in eastern, western, northern and central NY, all on farms that have typical NY cropping practices that incorporate manure and/or cover crops.  Stand counts will be taken to measure plant populations and to determine insect pest pressure, and yields will be measured to compare the three seed treatments:  1) neonic + fungicide, 2) diamide + fungicide, and 3) fungicide only.

Regardless of our results, we will need multiple years of study to better characterize the pest pressure.  Ideally, we would determine methods to predict and monitor seedcorn maggot pressure in individual fields and years for exploring biological, cultural and genetic means for suppressing these insects.  However, this has proven challenging, as evidenced by the current situation in Canada.

Stay tuned for the results of these studies later this fall.  And, I want to extend my sincere gratitude to all parties involved for coming together to conduct this research on extremely short notice.  Thank you to Seedway for donating the seed, to Syngenta for donating the seed treatment products, to the participating farmers who are taking time out of their busy schedules to plant and harvest these trials, and to our CCE and PRO-Dairy collaborators (Joe Lawrence, Mike Hunter, Mike Stanyard, Aaron Gabriel and Janice Degni) for volunteering their time to conduct this important research.  THANK YOU!!!

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