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Agronomic Crops Network

Ohio State University Extension


Corn Planting and Pollinators: Research Update

Honeybees on comb

The winter of 2019-2020 was relatively mild in both temperature and harmful effects on Ohio’s honey bee colonies.  While many beekeepers have experienced a normal (30-40%) die-off since last October, many of the colonies that made it through the winter look particularly robust.  The colonies we manage at Waterman Farm and near Farm Science Review are bursting with bees and raising new queens in anticipation of swarming over the next few weeks.

While colonies appear to be doing well, beekeepers continue to be worried that their bees’ success could be compromised by exposure to insecticidal dust produced during corn planting.  Research at apiaries in corn growing areas west of Columbus demonstrated that honey bees can be exposed to high levels of the neonicotinoid insecticides that constitute much of the seed coating.  This occurs as seeds rub against each other during handling and planting to generate a fine dust that is emitted along with air in pneumatic planters.  Both dust generated during planting and the dust left behind in the planter contain high levels of insecticide and may kill bees if they encounter it.  Studies conducted in 2013-2015 showed a substantial increase in the number of dead bees ejected from colonies during corn planting.  A follow-up study, conducted in 2019, showed that bees were exposed to much less corn seed treatment insecticide in that year and fewer honey bees died while corn planting activity was occurring.  Whether this improvement in 2019 is due to better seed treatment application, new seed lubricants, or the very extended planting season that occurred in 2019 is an open question. 

While technological innovation and luck undoubtedly play a role in reducing bee exposure to corn seed treatment insecticides during planting, there are a few simple things that can be done to further reduce honey bee exposure 1) starting with clean and weed-free fields that are uninteresting to honey bees; 2) following recommendations for using talc or other seed lubricants; 3) following proper planter clean-out and disposal procedures when finished to minimize escape of seed treatment dust.  More advice on protecting bees during corn planting and throughout the year can be found in the “Best Management Practices for Pollinator Protection in Field Corn” ( published by the National Corn Growers Association and the Honey Bee Health Coalition.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.