Bt Corn: Tighter EPA Regulations Are Pending

This week the EPA released a draft plan that essentially overhauls many of the regulations around insect resistance management (IRM) in Bt crops grown in the “cotton belt”.

There are many major changes proposed, one of which is that field failures are presumed to be cases of “practical resistance” if certain criteria are met. (Like 6% boll damage in third generation (Vip) cotton and second instar bollworm larvae are present, which is basically the treatment threshold we use now.)

Seed companies can then make collections and do the insect rearing and testing to refute the determination of resistance, if they want to do so. This is totally opposite of the way things have been done for 25 years. In the past, field failures were presumed to be from susceptible insects, and only laboratory testing could determine whether the insects were resistant.

Seed blend corn refuge will be approved for southern planting. However, a 20% structured (block) refuge will also be required with fields planted to seed blends. This block refuge is basically insurance until we can figure out whether seed blends are a good thing or a bad thing, as some of the data say they might accelerate resistance.

In the last four years there has been an all out effort by the seed industry and Land Grant Universities to answer this question, and if it turns out that seed blends are safe then the requirement for a block refuge could be dropped in the future. ABSTC (the Agricultural and Biological Stewardship Technical Committee, a consortium funded by Bayer, Corteva (Pioneer) and Syngenta), sponsored a very expensive and detailed seed blend trial that Dr. Suhas Vyavhare and I conducted near Olton this year.

Bayer sent a large crew of people to help on the days we could not possibly have done all of the work ourselves. I am grateful that Bayer and their excellent people stepped in at their own expense to help us answer this important question; we could not have done it without them. We are all trying to answer the seed blend questions as quickly as possible.

The new rules, if enacted as currently proposed, will change things at the farm level. I am quoting from the document directly.

  • “Sales of Bt corn products requiring block refuges must be followed up with on-farm visit by the seed industry for compliance monitoring by ABSTC during the growing season. This will be conveyed to growers at the point of sale and be included in the grower agreement. Visits will be reported to the Agency [EPA].
  • For farmers out of compliance with block refuge standards in the cotton belt for one year, the registrant [seed company] will withhold all the company’s Bt corn products, including RIB and block refuge for two years.
  • Registrants must ensure that seed dealers obtain signed grower agreements that set forth the terms of the IRM program. If a seed dealer fails to ensure that at least 95% of the customers sign grower agreements, registrants will restrict the availability of the Bt seed to that dealer. Registrants must ensure that seed dealers keep a record of signed grower agreements for a period of at least three years from sale.
  • Industry must ensure availability of non-Bt elite corn hybrids for refuge.”
Why is EPA doing this? Basically it is because corn earworm/cotton bollworm is now resistant to all but one Bt toxin, Vip3a. Refuge rules were not well followed in the past, and now resistance has come home to roost. If we are to prevent resistance to Vip3a, the last effective toxin for bollworm, things need to change. Prior to this we were operating under the set of rules mostly set forth in 1996, and there were some major problems with them. The new guidelines correct several of the mistakes made in the past.

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The EPA document is not final, and in several places it goes out of the way to ask for input from producers and consultants. I know the woman who wrote the document and is in charge of changing it, and she sincerely wants to hear from you on how these proposed changes will affect you, and whether there is a better way to accomplish the objectives. I trust her to listen to you. You can be assured that the anti-Bt crop lobby will be submitting comments, so here is your chance.
The 24-page draft document is here. The docket where you can submit your comments is here. I would be glad to answer any question about the proposed changes, and you can write me at p-porter@tamu.edu.



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