By Tracey Baute, OMAF Field Crop Entomologist, From fieldcropnews.com
With corn planting season soon upon us, it is a good time to remind everyone to take extra precautions to try to reduce the risk to bees being exposed to neonicotinoid contaminated dust from corn planters. Virtually all corn seed is treated with a neonicotinoid insecticide (ie. Poncho or Cruiser), and with over 200 incidences of bee kills in Ontario in the spring of 2012, we all have a role to play in trying to keep these incidences from happening again.
Factors that may contribute to the issue: Seed lubricants (ie talc or graphite) are abrasive and rub the insecticide seed treatment off of the seed and carry it into the air. Negative vacuum air planters likely contribute to this by exhausting the contaminated dust into the air, instead of onto the ground like other planters do. Dry, windy and warm weather also likely played a role, both for early than usual bee foraging activity and helping to carry the dust further outside the field. This however does not mean that this issue could not occur under different weather and field conditions.
Best management practices to help mitigate the risk to bees include:
- Communicate with beekeepers who have hives in your area. Bees can forage up to 5 km from their hives and likely venture in and around your fields. Let the local beekeepers know when you plan to plant. There may be steps that they can take to protect their hives during planting.
- Adjust time of planting. If there is an opportunity to plant in the early morning or evening on windy days, when bees are less likely to be foraging, it may also help to reduce the risk of exposure to contaminated dust.
- Manage dandelions and other flowering weeds in and around fields, prior to planting.
- Minimize the amount of insecticide seed treatment used. Growers planting corn on corn with moderate to high populations of corn rootworm, should use Bt hybrids that have two different Bt traits to control CRW, instead of using high rate of seed treatments which are not as effective. Get back to integrated pest management. Evaluate your fields and determine if soil pests are present at threshold levels this spring and start thinking about whether an insecticide seed treatment is actually needed.
- Limit the amount of seed lubricant (ie. talc or graphite) used at planting. Currently used lubricants are abrasive to the seed coat, rubbing the insecticide seed treatment off and help to carry the contaminated dust into the air. There has been a tendency to err on the “safe side” for planter performance, applying lubricant at the upper end of the label rate. Follow label recommendations as the amount of lubricant needed varies by planter. A build-up of talc on the blower exhaust indicates overuse.
- Exhaust dust towards the center of the field. If your planter exhausts air towards the right side, plant in a clockwise direction. This will help direct the dust into the field rather than directing the dust onto the vegetation and water sources near the field’s edge.
- Modifying planters with deflectors. Deflecting exhaust air directly at or into the ground will reduce the distance the contaminated dust is able to travel. Deflectors have yet to be tested here in North America to determine their impact both on planter performance and on efficacy to reduce dust concerns. Research into this option is currently under development.
Following all of these measures does not guarantee that bee incidences won’t occur in 2013 but we can not afford to neglect the role that pollinators play in agriculture and society in general. Planting time can be a frantically busy time but is important to do what we can to help protect the bees from any risks posed by agricultural practices.