By Jon Tollefson and Erin Hodgson, Department of Entomology
Due to toxicity and potential environmental hazard, the Environmental Protection Agency (EPA) has announced its intention to revoke all tolerances for carbofuran. Carbofuran is the active ingredient of Furadan™ 4F, most commonly used in Iowa as a liquid formulation applied to corn.
The Agency's announcement is in the Federal Registry and states that the final rule revoking all tolerances for carbofuran will be effective on August 13, 2009.
The announcement of the EPA's intended actions was followed a public announcement from Iowa Secretary of Agriculture Northey to increase Iowans' awareness of the cancelation.
This process began several years ago. A Risk and Benefits Committee reported to the EPA that carbofuran was an unduly hazardous chemical and there were alternative treatments that could be used. In 2006 FMC Corporation, the makers of Furadan™, requested an opportunity to appear before the Committee. Tollefson was an academic expert on Furadan use in field crops and a Professor from Purdue testified concerning Furadan use in horticulture crops. There were letters from Secretaries of Agriculture supporting the use of Furadan in crops, data from field experiments, and several growers testified.
Upon considering the information presented, the EPA maintained its intention to not renew the registration of carbofuran. FMC appealed the decision, but the appeal was not upheld. The process has now come to the point where the final cancellation of tolerances is occurring. It is likely that FMC will challenge the EPA's conclusions by requesting an administrative hearing, but these rebuttals have not altered the Agency's direction to this point.
Now how does this affect the Iowa growers? There are several points to consider:
• This year you will be able to purchase and use Furadan on field crops according to the label.
• Don't purchase and stockpile labeled Furadan. Any crops receiving a Furadan application after January 1, 2010 cannot be legally sold.
• Historically, there has not been very much liquid Furadan used in Iowa. However, this has changed somewhat with the development of genetically engineered corn that is resistant to corn rootworms; the requirement of a refuge planting to preserve effectiveness of the Bt varieties; the development of neonicotinoid seed treatments; and planters that have central-fill seed hoppers. These changes have resulted in Bt and refuge fields being planted with no soil insecticide applied for corn rootworm control and a liquid application being made to the refuge after the corn has emerged. Furadan has been a product that fits these needs. Now an alternative product will be needed.
If alternative treatments for protecting corn from corn rootworm larval feeding are needed, what might be available? If the area planted is to be a corn rootworm refuge, there would be two options: one option would be to add granular applicator units to the planter and the second would be to buy seed that has been treated with the rootworm rate of a neonicotinoid insecticide (e.g., Poncho™, Cruiser™). If a post-emergence liquid treatment is desired, the options would include chemicals such as Lorsban™ 4E and Capture™ 2EC. In general the planting-time granular insecticides provide the best, most consistent control. There is not as much research information on post-emergence liquid applications.
Jon Tollefson is a professor of entomology with responsibilities in research and extension. Erin Hodgson is an assistant professor of entomology with extension and research responsibilities. She can be contacted by email at firstname.lastname@example.org or phone (515) 294-2847.