BIOPESTICIDES REGISTRATION ACTION DOCUMENT

Optimum® AcreMaxTM B.t. Corn Seed Blends 

 

U.S. Environmental Protection Agency (EPA) 

 Office of Pesticide Programs 

Biopesticides and Pollution Prevention Division (BPPD) 

Updated August, 2011
Optimum AcreMax B.t. Corn Seed Blends Page 2 of 54 

Biopesticides Registration Action Document

TABLE OF CONTENTS

I. OVERVIEW ................................................................................................................. 3

A. BACKGROUND ...................................................................................................................... 3

B. USE PROFILE ......................................................................................................... 3

II. INSECT RESISTANCE MANAGEMENT ................................................................. 6

III. BENEFITS - CORN ROOTWORM SEED BLEND ................................................. 15

IV. REGULATORY RATIONALE .............................................................................. 17

V. TERMS AND CONDITIONS FOR NEW ECB SEED BLENDS.............................. 23

OAM; EPA REGISTRATION NUMBER 29964-12....................................................... 23

OAM XTRA; EPA REGISTRATION NUMBER 29964-11 ............................................ 35

VI. REFERENCES ....................................................................................................... 50
Optimum AcreMax B.t. Corn Seed Blends Page 3 of 54 

Biopesticides Registration Action Document

I. OVERVIEW 

 A. BACKGROUND 

On April 30, 2010, EPA conditionally registered the plant-incorporated protectant products, 

Optimum® AcreMaxTM 1 (OAM1), a seed blend of 90% HERCULEX® XTRA and 10% 

HERCULEX® I, and OAM RW, a seed blend of 90% HERCULEX® RW and 10% Non-B.t.

Corn. These registrations were originally set to expire on September 30, 2010. The registrant 

for both products is Pioneer Hi-Bred International, Inc. (Pioneer). OAM1 is the first registered 

B.t. corn product to incorporate a "blended" refuge; i.e., the OAM1 product requires a 10% 

refuge for corn rootworm, and the corn rootworm refuge seed is sold within the same seed bag as 

the B.t. corn rootworm product. (OAM1 also requires a separate 20% refuge for lepidopteran 

pests, and that refuge is in the form of a structured refuge that is sold separately). 

EPA considered amending the OAM products at the same time as other expiring Bt corn 

registrations. Consistent with the policy of making registration actions more transparent, the 

proposed amendments to the expiring OAM1 and OAM RW corn products were subject to a 30-

day comment period, along with other Bt corn PIPs, expressing different proteins effective in 

controlling various lepidopteran and coleopteran pests, that were set to expire in 2010 (Docket 

Number EPA-HQ-OPP-2010-0607). Based on all data submitted in support of the expiring 

OAM1 and OAM RW corn registrations and in consideration of the public comments received, 

the Agency concluded that it is in the best interest of the public and the environment to amend 

the currently existing OAM1 and OAM RW registrations by extending the current expiration 

dates to September 30, 2012. These amendments were granted on September 29, 2010. The basis 

for this decision can be found within this Biopesticides Registration Action Document (BRAD). 

 

On April 19, 2010, Pioneer applied to register two new seed blends that incorporate the 

lepidopteran refuge within the seed blend in the bag. Optimum® AcreMaxTM Xtra Insect 

Protection contains a seed blend with 90% 1507xMON810x59122 (Cry1Ab x Cry34/35Ab1 x 

Cry1F) and 10% Non-B.t. Corn. Optimum® AcreMaxTM Insect Protection contains a seed blend 

with 95% Optimum® IntrasectTM (Cry1Ab x Cry1F) and 5% Non-B.t. Corn. 

B. USE PROFILE 

Active Ingredients: 

Bacillus thuringiensis Cry34Ab1 and Cry35Ab1 proteins and the genetic 

material necessary for their production (PHP17662 T-DNA) in event DAS-59122-7 corn (OECD 

Unique Identifier: DAS-59122-7) 

Bacillus thuringiensis Cry1F protein and the genetic material (plasmid insert PHI8999A) 

necessary for its production in corn event DAS-Ø15Ø7-1 

Bacillus thuringiensis Cry1Ab delta-endotoxin and the genetic material necessary for its 

production (Vestor PV-ZMCT01) in event MON 810 corn (OECD Unique Identifier: MONØØ81Ø-6) 
Optimum AcreMax B.t. Corn Seed Blends Page 4 of 54 

Biopesticides Registration Action Document

Trade & Other Names: 

HERCULEX® I => Cry1F Corn 

HERCULEX® RW (Rootworm) => Cry34/35Ab1 Corn 

 

HERCULEX® XTRA => Cry1F + Cry34/35Ab1 Corn 

MON810 => Cry1Ab Corn 

Optimum® AcreMaxTM 1 (OAM1) => Seed Blend of 90% HERCULEX® XTRA 

and 10% HERCULEX® I 

OAM RW => Seed Blend of 90% HERCULEX® RW and 10% Non-B.t. Corn 

Optimum® AcreMaxTM Xtra Insect Protection => Seed Blend of 90% Cry1Ab x Cry1F x 

Cry34/35Ab1 and 10% Non-B.t. Corn 

Optimum® AcreMaxTM Insect Protection => Seed Blend of 95% Cry1Ab x Cry1F 

and 5% Non-B.t. Corn 

OPP Chemical Codes: 006490 (Cry34/35Ab1 corn), 006481 (Cry 1F corn), and 006430 

(Cry1Ab corn) 

Type of Pesticide: Plant-Incorporated Protectants (PIPs) 

Product Profile: 

HERCULEX® I

The registration for Cry1F Event TC1507 (Event DAS-01507-1), also known as HERCULEX® 

I, was first granted by the Agency on May 18, 2001. HERCULEX® I expresses the Cry1F 

insecticidal crystal protein as well as the PAT (phosphinothrin acetyl transferase) protein, which 

confers tolerance to the herbicidal active ingredient glufosinate-ammonium. Cry1F is efficacious 

against lepidopteran pests, and the primary target pest of HERCULEX® I is the European corn 

borer (ECB, Ostrinia nubilalis); other target pests are corn earworm (CEW, Helicoverpa zea), 

southwestern cornborer (SWCB, Diatrea grandiosella), fall armyworm (FAW, Spodoptera 

frugiperda), western bean cutworm (WBCW, Richia albicosta), and black cutworm (BCW, 

Agrotis ipsilon). The main target pests for which insect resistance management (IRM) 

requirements apply are ECB, CEW, and SWCB. 

HERCULEX® RW

The registration for Event DAS-59122-7, also known as HERCULEX® RW, was granted by the 

Agency in August, 2005. HERCULEX® RW expresses B.t. toxins Cry34Ab1 and Cry35Ab1, 

which are efficacious against coleopteran pests. The primary target pests of HERCULEX® RW 

are western corn rootworm and northern corn rootworm (CRW, Diabrotica species). Maize 

containing Event 59122-7 has been modified to express the PAT protein, which confers tolerance 

to gluphosinate-aluminum herbicide. 
Optimum AcreMax B.t. Corn Seed Blends Page 5 of 54 

Biopesticides Registration Action Document

HERCULEX® XTRA

The registration for HERCULEX® XTRA (Event TC1507 x DAS59122-7) was granted in 

October 2005. HERCULEX® XTRA is the result of a conventional breeding cross between 

HERCULEX® I and HERCULEX® RW and is considered a stacked PIP because it targets two 

different kinds of pests (Lepidoptera and Coleoptera) and contains two separate PIP active 

ingredients. 

OAM1: EPA Registration Number 29964-6

Optimum® AcreMaxTM 1 Insect Protection, a blended seed product that contains two different 

kinds of seeds of the already registered products HERCULEX® XTRA and HERCULEX® I 

was registered on April 30, 2010. The product incorporates the CRW refuge into the seed bag. 

The seed blend percentage was amended to 90% HERCULEX® XTRA and 10% HERCULEX® 

I. 

OAM RW: EPA Registration Number 29964-10

Optimum® AcreMaxTM RW Insect Protection, a seed blend consisting of 90% HERCULEX® 

RW and 10% non-B.t. corn was registered on April 30, 2010. The product incorporates the CRW 

refuge into the seed bag and also can serve as a refuge for the Cry1F portion of OAM1. 

Optimum® IntrasectTM: EPA Registration Number 29964-7

Optimum® IntrasectTM is a Bt corn with Cry1Ab and Cry1F both targeting European corn borer 

and southwestern corn borer and was registered on February 24, 2010. 

1507x MON810x59122: EPA Registration Number 29964-8

1507x MON810x59122 is a Bt corn with Cry1Ab and Cry1F targeting European corn borer and 

southwestern corn borer and Cry34/35Ab1 targeting corn rootworm. It was registered on 

February 24, 2010. 

OAM: EPA Registration Number 29964-12

OAM is a blended seed product that contains two different kinds of seeds of the already 

registered product Optimum® IntrasectTM (95%) and 5% Non-B.t. Corn. 

OAM Xtra: EPA Registration Number 29964-11

OAM Xtra is a blended seed product that contains two different kinds of seeds of the already 

registered product 1507x MON810x59122 (90%) and10% Non-B.t. Corn. 

Pioneer’s Projected Use in 2010, 2011, and 2012

Pioneer’s forecast for OAM1 U.S. acreage in the 2010, 2011, and 2012 growing seasons is listed 

below. Pioneer states that “[t]hese estimates have been divided into high-pressure areas for corn 

rootworm (i.e., the Red Zone) and non-Red Zone acres (i.e., the remaining U.S. corn acreage 

outside the Red Zone). The Red Zone is defined by Pioneer as 90 counties that have a 100% 

chance of corn rootworm infestation in any given year. These counties are primarily located in 

northeastern Illinois, northwestern Indiana and, to a lesser extent, southeastern Wisconsin and 

southwestern Michigan. Because of the strong selection pressure present in the Red Zone, it is 

considered a potential area for corn rootworm resistance to develop. The percentages are based 

on general USDA acreage projections, which project a total of 90 million corn acres in the U.S. 

in 2010, 2011, and 2012.” 

 
Optimum AcreMax B.t. Corn Seed Blends Page 6 of 54 

Biopesticides Registration Action Document

Growing season Red Zone geography Non-Red Zone geography 

2010 ~0.077% ~0.042% 

2011 ~5.8% ~8.2% 

2012 ~8% ~12% 

Pioneer provided information to EPA indicating that the total OAM1 acres planted in 2010 was 

34,804, which is less than originally projected. (Rood 2010). Pioneer has not changed the initial 

 projections for 2011 and 2012. 

II. INSECT RESISTANCE MANAGEMENT 

A. Corn Rootworm 

FIFRA Scientific Advisory Panel (SAP)

Pioneer/Dupont's initial registration application for OAM1 consisted of a seed blend of 95% 

HERCULEX® XTRA and 5% [3.5% (±1.5)] HERCULEX® I. The HERCULEX® I was 

intended to serve as the IRM refuge for the corn rootworm active component of HERCULEX® 

XTRA. The proposed seed blend strategy and reduction in refuge from 20% to 2% to 5% 

represented a significant paradigm shift for the B.t. IRM strategy that has been employed for 

over 15 years. BPPD conducted a risk assessment and presented preliminary conclusions to the 

Scientific Advisory Panel for peer review on February 23 to 24, 2009. 

The SAP (2009) expressed concern about the proposed refuge reduction. The Panel concluded 

that there was no compelling evidence, either in the data provided by Pioneer or in the public 

literature, to support a 5% blended refuge for this particular product. The Panel noted, however, 

that the biology of the corn rootworm makes it susceptible to successful control and mitigation 

by a seed blend methodology, if the refuge is of sufficient size. 

Ad hoc members of the SAP commented on EPA's grant of the OAM1 registration for 2010. 

These members noted that the 2009 SAP had voiced concerns on the simultaneous approval of a 

blended and reduced refuge for corn rootworm, and stated that EPA "ignored" the 2009 SAP's 

general conclusion to retain a 20% refuge while research continues. In granting a registration for 

sale and distribution of OAM1 for the 2010 growing season, EPA did consider and rely upon the 

advice of the SAP. Pioneer's initial application sought approval for a 2.5 % blended refuge and 

that is what EPA took before the SAP. Concerns raised by the SAP were a major factor in why 

the Agency did not approve the 2.5% blended refuge proposal. Moreover, the concerns raised by 

the SAP, and other commenters, are a significant factor in certain of the unique terms and 

conditions that EPA is placing on the OAM1 registration for 2011 – 2012. The ad hoc members 

also commented that the SAP's concerns regarding Pioneer's hypothesis concerning mode of 

action were not addressed. EPA did not specifically address the SAP's recommendation on the 

mode of action hypothesis because that hypothesis did not play a role in our decision. EPA 

similarly has concerns as to the validity of the mode of action hypothesis and did not in any way 

factor this hypothesis in our decision. 

OAM1 is a blended seed product that contains 90% HERCULEX® XTRA seeds (Cry34/35Ab1 

x Cry1F) and 10% HERCULEX® I seeds (Cry1F). 

OAM RW is a blended seed product that contains 90% HERCULEX® RW seeds 

(Cry34/35Ab1) and 10% non-B.t. Corn. 
Optimum AcreMax B.t. Corn Seed Blends Page 7 of 54 

Biopesticides Registration Action Document

Seed Blending

Pioneer submitted information and analyses supporting their claim that refuge plants will be 

randomly distributed throughout the field, including information indicating that the expected 

error of mixing the refuge seed is ±1.5% (using the seed mixing technology described in their 

submission) and that the standard deviation for planting the correct percentage of refuge is ±1%. 

IRM Modeling

EPA Model Description 

EPA'S POPGEN (Population Genetics) simulation models are a series of generalized, flexible 

population genetics modeling systems modeling the evolution of resistance to conventional 

pesticides and transgenic crops. The programs are capable of simulating complex landscapes that 

vary spatially as well as temporally over the course of a growing season. 

POPGEN-D 

The deterministic model POPGEN-D is a relatively simple frequency-based model that 

incorporates non-compliance estimates, non-random mating in refuge fields, and larval 

movement. The model permits modeling of both block refuges and blended seed-mixture 

refuges. 

POPGEN-S2 

The stochastic model POPGEN-S2 is a modification of an earlier stochastic, spatially explicit, 

dual locus, simulation model designed to evaluate the development of resistance in crop pests to 

insecticides. (Caprio et al 2006). 

 

POPGEN-SM 

The stochastic model POPGEN-SM is a modification of an earlier stochastic, spatially explicit, 

dual locus, simulation model designed to evaluate development of resistance in crop pests to 

insecticides and incorporating multi loci. (Caprio et al 2006). 

To incorporate uncertainty in the parameters used in the deterministic model, distributions, based 

on data for the lowest and maximum possible values, were developed as well as a most likely 

value. These values were used in PERT distributions based on a beta distribution with the most 

likely value weighted by 4 (Vose 2001). 

Dr. David Onstad of the University of Illinois commented that it was difficult to understand 

EPA's modeling because insufficient detail on the design and inputs was included in the docket 

for the initial registration. We recognized that it would have been useful to place more 

information on the modeling in the docket. Unfortunately, this information was not ready for 

release at the start of the comment period. We supplemented the docket with additional 

information on the model and model inputs during the comment period. Dr. Onstad also 

suggested that EPA's modeling efforts should be more transparent and should include more 

explicit explanation of how the modeling was conducted. We hope that the additional 
Optimum AcreMax B.t. Corn Seed Blends Page 8 of 54 

Biopesticides Registration Action Document

information provided to the docket addressed the concerns regarding transparency. Also, EPA 

will convene a public meeting of the SAP to evaluate these models in early December. We urge 

all interested parties to participate and submit comments at that time. Additional information on 

this meeting of the SAP will be available within the normal time frame. 

5% Seed Blend

Subsequent to the February 2009, FIFRA Scientific Advisory Panel meeting, Pioneer submitted 

revised modeling that incorporated new corn rootworm movement data. EPA fully evaluated 

this modeling, including assessing the new corn rootworm movement data. In addition, using the 

POPGEN model developed by EPA ORD, EPA conducted an independent modeling analysis of 

Pioneer's proposed seed blend using both deterministic and stochastic models. EPA concluded 

that a number of critical input parameters to the Pioneer modeling were not supported by data or 

were inadequate to support a rational basis for regulatory decisionmaking. Therefore, BPPD 

concluded that the results of the Pioneer modeling indicating that the proposed 5% seed blend is 

superior to a 20% block refuge deployment strategy for OAM1 and corn rootworm were not 

scientifically supported. 

EPA had concerns regarding Pioneer's assumptions about short range insect dispersal because 

the data (Nowatzki et al. 2003) were limited, and were derived from only one location in the 

cornbelt. This was a critical factor because the adult insect dispersal input is a sensitive 

parameter for modeling the durability of block refuges. Parameter inputs representing a shorter 

dispersal range lowered the resulting effectiveness of a block refuge. Using a range of 

representative parameter values and assumptions to predict the durability of a 20% block refuge 

versus Pioneer's proposed 5% blended refuge, EPA's deterministic modeling showed that the 

predicted durability for the 20% block refuge was superior to a 5% seed blend strategy (11.95 

years vs. 8.1 years). 

In addition to the 5% seed blend, EPA modeled other blend percentages for comparison. A 10% 

seed blend was predicted to have a durability of 11.3 years, which was slightly less durable 

(5.4%) relative to a 20% block refuge based on EPA's assumptions. EPA concluded, however, 

that these results were of limited actual utility because a number of parameter inputs to the 

original Pioneer model did not reflect actual variability and/or uncertainty. Therefore, to assess 

the current application for a 10% blended refuge, EPA conducted modeling using a range of 

representative input parameters. 

10% Seed Blend 

In the latest modeling, EPA incorporated uncertainty by using probabilistic distributions of 

critical data that we determined to be variable and/or uncertain. The analysis was based on a 

PERT-Beta distribution (minimum value, most likely, and maximum value) for parameters of 

uncertainty. Each simulation was run1,000 times, and each run utilized input parameters drawn 

from the PERT distributions. "Resistance" was defined as the resistance allele exceeding 50%, 

and EPA measured the mean, 25th, and 75th percentiles of the time to "resistance." EPA also 

determined the proportion of simulations where the time to resistance exceeded 11 years. (The 

SAP has advised that 15 years with no resistance is a reasonable goal for an IRM program 

applicable to a single-gene toxin. The Cry34/35 transgenic toxin has been in use for four years. 

Therefore, we believe it relevant to assess how many of the simulations indicate that either the 

20% block or the 10% blend will delay development of resistance for 11 or more years.) The 
Optimum AcreMax B.t. Corn Seed Blends Page 9 of 54 

Biopesticides Registration Action Document

data analysis indicated comparative durability values of 11.3 years for the 10% blended refuge, 

yet 20.2 years of durability for the 20% block refuge. Thus, the 10% blend was 45% less durable 

than the 20% block refuge currently required for single trait CRW PIPs. 

IRM Refuge Compliance

Critical to an assessment of the likely efficacy of an IRM mitigation program is the level of 

compliance with that program. Data received by EPA from the Agricultural Biotechnology 

Stewardship Technical Committee (ABSTC) indicate that compliance with the paradigmatic 

20% block refuge requirement for most B.t. corn crops has been steadily decreasing. As noted 

by a number of commenters, this decreased compliance increases the risk of resistance 

development (see, e.g., Complacency on the Farm, CSPI 2009, and Impact of Genetically 

Engineered Crops on Farm Sustainability in the United States, NAS 2010). 

For the 2002 to 2008 planting seasons, ABSTC reported refuge compliance either as ‘all 

compliant' (i.e., always planting a 20% refuge, within the proper distance) or 'out-of-compliance’ 

(i.e., not having either a 20% refuge, or having the refuge not located exactly where required, or 

neither). In 2007 and 2008, ABSTC began to also report if growers at least planted a 15% refuge 

or/and if most of a grower's B.t. fields met the refuge distance requirement. (Reporting these 

additional data reflects that there may be degrees of noncompliance, for example, a grower may 

be inadvertently out of compliance with distance requirements by a degree that does not 

materially affect the efficacy of the refuge. Also, while, admittedly, a 15% refuge is not 

compliant with a 20% refuge requirement, it has a much different field impact than does a 0% 

refuge.) 

The graphs and chart below compare compliance data from the ABSTC telephone and online 

surveys. 
Optimum AcreMax B.t. Corn Seed Blends Page 10 of 54 

Biopesticides Registration Action Document
Optimum AcreMax B.t. Corn Seed Blends Page 11 of 54 

Biopesticides Registration Action Document

Telephone and Online Survey for Bt Protected Corn 

2002-2010 

Refuge 

Compliance Refuge Distance 

year Refuge Size CRW PIPs Stacks year ECB PIP 

CRW 

PIPs Stacks 

'02 86 '02 89 

'03 92 '03 93 

'04 91 '04 96 

'05 92 93 '05 96 87 

'06 89 89 78 '06 96 82 92 

'07 80 80 70 '07 88 79 66 

'08 78 74 72 '08 88 63 66 

'09 74 79 71 '09 78 71 67 

'10 76 73 69 '10 87 67 63 

B. European Corn Borer and Southwestern Corn Borer 

An SAP meeting (December 2010), convened to evaluate a similar seed blend product, 

concluded (based on modeling analysis) that a dual gene, high efficacy product with a seed blend 

approach targeting ECB and SWCB was less durable than a block refuge of equivalent non-Bt 

proportion (SAP 2011). 

BPPD reviewed biological data and simulation modeling for lepidoptera pest of corn that was 

submitted by Pioneer/DuPont to support a registration request for a 5% Optimum AcreMax 

(expressing Cry1F and Cry1Ab) and 10% Optimum AcreMax Xtra RIB (expressing Cry1F, 

Cry1Ab, and Cry34/35) (BPPD 2011a). BPPD identified a number of concerns and deficiencies 

with the proposed refuge strategies and was unable to quantify the relative durability of the 

proposed seed blends at that time (BPPD 2011a), yet concluded that a 5% block refuge was more 

durable than a 5% RIB (SAP 2011). Pioneer/DuPont responded to the Agency’s review by 

resubmitting additional explanations and modeling (MRID 485219-01) to address the 

uncertainties and deficiencies . 

Pioneer’s Results:

Pioneer/DuPont reported that inflating the fecundity of ECB and SWCB to avoid extinction and 

effects of genetic drift, as recommended by BPPD, lead to unrealistically small durability 

estimates as was evident for the single toxin simulations. For single PIPs deployed with a 20% 

structured refuge, estimated durabilities were less than the actual time the products had been 

commercialized. The applicant recommended that results be considered relative to each other 

rather than viewed as absolute predictions. 

The applicant concluded that a 5% Optimum AcreMax RIB was more durable against ECB and 

SWCB than either single gene PIP deployed with a 20% structured refuge irrespective of the fact 

whether the refuge was kept in the same location each year or randomly assigned between two 

possible locations. When benchmark and worst-case assumptions were considered, the 5% RIB 

scenarios were estimated to be between 7-36 fold and 4-6 fold more durable than the single 

toxins MON810 (Cry1Ab) and 1507 (Cry1F), respectively, deployed with a 20% block refuge. 

When the same comparisons were made for SWCB under the same benchmark and worst-case 
Optimum AcreMax B.t. Corn Seed Blends Page 12 of 54 

Biopesticides Registration Action Document

assumptions, then the durabilities for a 5% RIB were 18-58 and five-fold more durable than the 

single toxins MON810 and 1507, respectively.

Furthermore, Pioneer/DuPont reported that a 5% MON810 x 1507 RIB was more durable than a 

10% RIB using the same pyramided toxins. The applicant reasoned that this was not unexpected 

based on the inflated fecundity levels chosen and the resulting increase in density dependent 

mortality on refuge plants in scenarios with a higher blend percentage compared to a lower blend 

percentage and cited to discussions in Ives et al. (2011) and SAP (2011) for support. A 5% RIB 

targeting ECB was only moderately more durable than the 10% RIB, while for SWCB the 

durability decreased nearly by half when the blend percentage increased from 5% to 10%. The 

applicant had set the (per-plant) carrying capacity at 18 larvae (Gen1) and 22 larvae (Gen2) for 

ECB and 1 larva (both generations) for SWCB and noted that if was difficult to determine 

whether the differences in durability seen between the two species was only a function of the 

different carrying capacities chosen (and DD-mortality) or whether differences in mating 

behavior could have also influenced the results.

The applicant stated that increasing the dominance value for the “pre-dispersal tasting 

mortality”1 value from 0.02 to 0.50 created a survival differential between SS and RS 

individuals that was not supported by the latest research (manuscript in process). 

The 5% block refuge scenario had the greatest durability of all simulated refuge options. But the 

applicant noted that compliance was modeled at 100% and that any compliance less than that 

would decrease the durability of the block refuge. The difference in durability between the 5% 

block and 5% RIB scenario would therefore be reduced if non-compliance was considered. 

BPPD Conclusions:

Pioneer/DuPont addressed the recommendations previously made by BPPD (2011): the applicant 

artificially inflated the fecundity for European and southwestern corn borers to avoid population 

extinction in their modeling analyses, included some worst-case values for several sensitive 

parameters in their new simulations, conducted a probability analysis to be able to report a risk 

profile to the Agency, and addressed the most germane uncertainties described by the SAP (2011) 

for seed blends with pyramided PIPs targeting Lepidoptera. Pioneer/DuPont did not include nonuniform oviposition by Lepidoptera in their main modeling analyses and explore greater female 

(southwestern corn borer) dispersal out of seed blends. 

After careful review of the applicant’s new modeling submission, BPPD concludes that: 

 The 20% single toxin block refuges had the lowest durability estimates of all options 

tested in Pioneer/DuPont’s model. Those durability results were, however, artificially 

reduced by higher fecundity assumptions. Pioneer/DuPont estimated blends to be 

between 6 and 60-fold more durable than 20% blocks for single toxin PIPs. 

 The proposed seed blends (5% and 10%) will likely be substantially less durable than a 

5% block refuge for the same product (100% compliance assumed). This was also 

concluded by the SAP (2011). With realistic assumptions of non-compliance the 

estimated durability for the block scenario would likely be somewhat lower but still more 

durable than the blends. Pioneer/DuPont’s model estimated that a 5% block had close to 

 

1 The proportion of CRW larvae that die upon initial feeding before movement. 
Optimum AcreMax B.t. Corn Seed Blends Page 13 of 54 

Biopesticides Registration Action Document

double the durability of blends for both pests (benchmark assumptions). The durability of 

the pyramided blends is highly likely to fall in between the two block options. They can 

be expected to be more durable than the single toxins (especially under assumptions of 

low cross-resistance). The uncertainties described below (effects of increased fecundity, 

no modeling of non-uniform oviposition and greater dispersal out of blends) can be 

expected to further erode the durability of blends. 

 A 10% blend is likely to be more durable than a 5% seed blend for the same product. 

Pioneer/DuPont reported, however, that the lower blend percentage had slightly greater 

durability than the higher blend percentage. Possible explanations for this unexpected 

outcome are discussed in the uncertainties section below. 

 These conclusions are based on all available information, including Pioneer/DuPont’s 

modeling, the 2011 SAP report, and EPA/ORD modeling analyses created for other seed 

blend products. Quantification of the risk (i.e. level of durability) for Optimum AcreMax 

and Optimum AcreMax Xtra is complicated by uncertainties in some biological 

parameters including uniform/non-uniform oviposition, effects of inflated fecundity, 

degree of female pre-ovipositional dispersal as well as aspects of the probability analysis. 

All these uncertainties together could functionally lower the durability of seed blends 

relative to block refuges. 

 In consideration of the cumulative effect of the uncertainties and without additional 

modeling, BPPD is unable to completely quantify the relative durabilities of the various 

refuge options. BPPD expects, however, the relative durability relationship to hold true: 

5% pyramid block > 10% pyramid seed blend > 5% pyramid seed blend > 20% 

single toxin block. 

 The 10% Optimum AcreMax 1 seed blend (expressing Cry34/35) targeting corn 

rootworm was approved in 2009. The applicant seeks to combine this single CRW gene 

with the pyramid PIP for Lepidoptera into a new 10% seed blend product (Optimum 

AcreMax Xtra). As stated above, the risk of resistance development and relative 

durability cannot be quantified for any of the proposed blends; however, BPPD expects 

the risk of resistance evolution to be lower for a 10% seed blend expressing two 

pyramided PIPs than a 5% blend as proposed for the Optimum AcreMax product 

targeting Lepidoptera only. 

BPPD has identified the following uncertainties in Pioneer/DuPont’s analysis: 

1) Non-uniform oviposition behavior was not included into Pioneer/DuPont’s benchmark 

simulations although a sensitivity analysis for this parameter showed a trend of greater 

durability for the 10% seed blend over the 5% blend when conservative, yet realistic, 

assumptions of non-uniform oviposition favoring Bt plants were included. Based on the 

advice received by the SAP (2011) as well as information published in Hellmich et al. 

(1999), BPPD concludes that any durability analysis of a seed blend application targeting 

lepidoptera should conservatively incorporate non-uniform oviposition in order to 

address situations where greater insect damage to refuge plants in a seed mixture could 

result in greater oviposition onto Bt plants. One of Pioneer/DuPont’s proposed products 

(Optimum AcreMax Xtra) contains a corn rootworm protectant gene; for PIP plants that 

receive additional below ground protection, early crowding out of refuge plants by Bt 

plants is another reason why non-uniform oviposition needs to be addressed in modeling 

analyses. 

2) Pioneer/DuPont’s durability estimates for the 5% seed blend were greater than for the 
Optimum AcreMax B.t. Corn Seed Blends Page 14 of 54 

Biopesticides Registration Action Document

10% seed blend strategy. BPPD determined that this non-intuitive result may have been a 

consequence of having inflated the fecundity of the target pests by 6- and 4-fold for ECB 

and SWCB. This unexpected outcome of greater durability for a blend containing a lower 

non-Bt proportion was also the topic of discussion in the SAP report (2011) and Ives et 

al. (2011). It was demonstrated there that by inflating fecundity greatly that a two-toxinpyramid in a seed blend with low non-Bt proportions could be driven to have increased 

durability over a blend with greater non-Bt proportions when target pests were mobile. In 

fact, the SAP demonstrated that at first the durability of seed blends increased with 

increasing proportion of non-Bt plants. Then a precipice was reached where durability 

began to decrease for blends with greater proportions of non-Bt plants. As fecundity was 

successively inflated, the precipice moved towards lower values of blends with non-Bt 

proportions. In other words, when fecundity was greatly increased, the effect was that 

there was greater mortality of susceptible genotypes as a result of density-dependence; 

this led to greater selection of resistant genotypes (Ives et al. 2011). “Because all sorts of 

variability are not considered in deterministic simulations, it is possible to push the model 

over the precipice, which marks the point on the graph where populations begin to head 

towards extinction and the density-dependent model becomes density-independent; 

accelerated resistance evolution can be observed at this point; the precautionary advice is 

to stay away from this precipice or boundary” (Ives, personal communication). 

Since the applicant’s durability estimates appear to be derived from beyond this boundary 

(precipice), BPPD concluded that it might be more meaningful to look at the sensitivity 

analysis conducted for non-uniform oviposition: when Bt plants were favored as 

oviposition sites, the fecundity of susceptible genotypes may have been indirectly 

reduced (for ECB but not so for SWCB) and density-dependence moved 

Pioneer/DuPont’s model back into the realm where durability estimates conformed to 

expectations under resistance evolution models and where seed blends with greater nonBt proportions had greater durability than those with fewer non-Bt plants. Modeling 

analyses conducted in the past by EPA/ORD also predicted that a greater percentage (i.e., 

10%) of refuge plants in a seed blend will be more durable than a lower percentage (i.e., 

5%) of refuge plants (BPPD 2010a and BPPD 2010b). BPPD also considered Carriere et 

al. (2004) who reported that differences in Bt durability predicted by block and seed 

blends of equal refuge plant proportions (caused by a reduction in refuge insects in seed 

blends) could be overcome by increasing the proportion of non-Bt plants in seed 

mixtures. 

3) Pioneer/DuPont conducted a sensitivity analysis for the “number of eggs produced in 

natal fields” by SWCB in block refuges (single and pyramided PIPs) but not for seed 

blend scenarios. The applicant reported that durability results for blocks were not very 

sensitive to changes in this parameter although a slightly decreasing trend in durability 

was noted for single PIPs as pre-ovipositional dispersal increased. For a 5% block refuge 

with a pyramided PIP (where no resistance evolved for the duration of the simulation – 

400 yrs), the applicant reported that the final resistance allele frequency was slightly 

higher when there was more dispersal out of the fields. This result agrees with what the 

SAP (2011) reported, namely, that with high female dispersal, resistance would evolve 

faster. Pioneer/DuPont did not compare the durability of blends to blocks when varying 

this parameter. This would have been an important relative comparison, since dispersal in 

blends requires adults to only move short distances away from the refuge plant before 

having dispersed from their “natal field”. Hence the effects of female pre-ovipositional 
Optimum AcreMax B.t. Corn Seed Blends Page 15 of 54 

Biopesticides Registration Action Document

dispersal out of seed blends can be expected to have a greater effect on resistance 

evolution in seed blends than block refuges. The SAP (2011) stated that “for seed 

mixtures dispersal rates will be 100%, and greater than between field refuges. The main 

consequence [of greater dispersal rates] is that seed mixtures will have faster resistance 

evolution than between field refuges”. 

Additional Data and Analysis Required:

In order to improve the strength of modeling, Pioneer/DuPont has been required to incorporate 

the following into their model and to clarify certain assumptions utilized: 

a) Non-uniform oviposition for both generations of lepidoptera in a 10% seed blend (OAM 

Xtra); 

b) Non-uniform oviposition for the second generation of lepidoptera in a 5% seed blend 

without a corn rootworm trait; and 

c) Increased female (SWCB) pre-ovipositional dispersal out of seed blends. 

d) How was fecundity increased in seed blends? Does the 6-fold (and 4-fold) increase refer 

to the fecundity of susceptible insects on refuge plants relative to fecundity on Bt plants? 

e) How was uniform oviposition dealt with in the model code? The methodology should be 

explained. Do adults form one big random mating pool in seed blends, and eggs are 

uniformly applied across the field (or else)? 

f) How was non-uniform oviposition dealt with in the model code of the sensitivity 

analysis? Pioneer/DuPont should explain the methodology used. 

The following seed blend related IRM data is being required to support a longer term analysis of 

the potential for insect resistance developing from the use of two toxin based Bt corn seed blends 

targeting European corn borer and southwestern corn borer. 

a) Ovipositional behavior in seed blends under, for example, increased pest pressure; 

b) The potential and degree of crowding out refuge plants by Bt protected plants in 

blends expressing corn rootworm traits under different environmental 

conditions and higher pest pressure; 

c) Adult movement (related to mating and movement from refuges), larval movement, 

larval feeding (i.e., selective feeding within corn ears or on pollen), survival of 

heterozygote genotypes on OAM (markers may need to be determined for heterozygotes), 

and the potential for epistatic mechanisms of resistance (particularly with older instars).

III.BENEFITS - CORN ROOTWORM SEED BLEND 

We expect OAM1 to have the following benefits: (1) Reduced pesticide use in the refuge. 

Currently, the 20% block refuge may be sprayed with pesticide to mitigate pest damage. The 

blended in-field refuge will not be sprayable. (2) Significantly less complicated refuge 

deployment for the corn rootworm active ingredient. Currently, to be fully compliant with the 

refuge requirements, growers must accurately calculate 20% of the field, accurately determine 

the proper distance for the refuge field, and properly plant the required acreage in the correct 

location. Moreover, there are temporal concerns, as the refuge field must be planted at, 

essentially, the same time as the yield field so that emergence of refuge rootworms is 

contemporaneous with emergence of field rootworms. Anecdotal reports from growers make 

clear that meeting each of these requirements can be challenging in the actual on-farm 
Optimum AcreMax B.t. Corn Seed Blends Page 16 of 54 

Biopesticides Registration Action Document

environment. A product with the refuge blended with the field seed will significantly ease 

deployment of the rootworm refuge. (3) Increased grower compliance with IRM requirements 

for the corn rootworm active ingredient. A seed blend product that incorporates an effective 

refuge in the seed bag necessarily leads to 100% compliance with refuge requirements for those 

growers planting that product. 

In addition, indirect benefits of introducing Optimum® AcreMaxTM 1 may include reduced 

energy consumption for manufacture, transport, and application of chemical insecticides; 

reduced waste streams arising from pesticide manufacture; reduced disposal of pesticide waste 

containers; and reduced residues from pesticide applications. 

Efficacy and Yield Benefits

Pioneer conducted a two year study (2006 to 2007) to assess efficacy and yield benefits of a 

blended seed refuge. The purpose of the study was to determine the effects of a blended refuge 

approach on field standability, root ratings, and yield (three effects measured at each treatment 

level). The 2006 experiment was replicated at eight different locations in a randomized block 

design with four replicates for all five treatments. The treatments were: (1) untreated control; 

(2) conventional seed treated with P1250; (3) 100% HXRW (HERCULEX® RW) seed treated 

with P250; (4) 10% seed mix of conventional seed treated with P250 and 90% HXRW seed 

treated with P250; and (5) 20% seed mix of conventional seed treated with P1250 and 80% 

HXRW seed treated with P250. During July 2006, five roots per plot were randomly selected, 

root damaged scored using the Iowa State 0-3 node injury scoring, and yield determined at end 

of the growing season. Under low insect pressure, Pioneer reports little difference in node injury 

or yields between treatments (no data provided). Under high insect pressure, all HXRW 

treatments had approximately equal grain yield and node injury and the 10% and 20% seed 

blends were equivalent to the control of 100% HXRW maize. 

The Center for Science in the Public Interest (CSPI) commented that our analysis of the benefits 

of OAM1 should consider overall IRM compliance, including that in the lepidopteran refuge. In 

addition, CSPI stated that EPA should require additional conditions related to the lepidopteran 

refuge, such as requiring that refuge requirements be placed on seed bags, requiring that on-farm 

assessments be conducted by third parties, requiring growers to certify compliance annually, and 

separating compliance data into geographic regions. EPA agrees with and is implementing a 

number of these suggestions. Pioneer has committed to including labeling on OAM1 seed bags 

indicating the size of the required refuge for lepidoptera, and this is being made a specific term 

of the registration. (We note that this is also being made a term of all B.t. corn registrations and 

that all B.t. corn registrants are required to make best efforts to implement this change on as 

many bags of seed as possible for the 2011 growing season, on 50% of seed bags for the 2012 

growing season, and on 100% of seed bags for the 2013 growing season). EPA is also requiring 

that on-farm assessments for all B.t. corn registrations must be conducted by independent, thirdparties. Also, compliance data will be required to be submitted in a form that will permit 

evaluation by geographic region. We are not, at this time, requiring that growers annually certify 

ex post facto that they complied with the IRM requirements; but, that is a requirement that we 

will consider in the future, should the compliance picture not improve. 

Dow AgroSciences commented that the requirement for a separate structured lepidopteran refuge 

would create confusion among growers. We agree that there is the possibility of grower 

confusion related to the fact that there must be two separate refuges for OAM1. Pioneer is 

required to conduct enhanced grower education to ensure that purchasers of OAM1 understand 
Optimum AcreMax B.t. Corn Seed Blends Page 17 of 54 

Biopesticides Registration Action Document

the lepidopteran refuge requirements. Pioneer also is responsible for 2000 independent, thirdparty on-farm assessments to address compliance with the lepidopteran refuge requirements. 

Significant non-compliance with the OAM1 lepidopteran refuge requirements, if verified, could 

have implications for continued availability of OAM1 in 2011 and beyond . 

 

In 2007, the study was repeated with the addition of HX1 (HERCULEX® I) as refuge seed 

(treated with P250 and P1250). BPPD did not see statistically significant differences between 

node injury, % root lodging, and grain yields between any of the HXX (HERCULEX® XTRA) 

treatments except with respect to node for the 20% refuge with P250. 

IV. REGULATORY RATIONALE 

A. 2010 Corn Rootworm Refuge in the Bag Registration Decision

Section 3(c)(7)(A) of FIFRA provides for the registration or amendment of a pesticide when the 

pesticide and proposed use “...are identical or substantially similar to any currently registered 

pesticide and use thereof, or differ only in ways that would not significantly increase the risk of 

unreasonable adverse effects on the environment, and (ii) approving the registration or 

amendment in the manner proposed by the applicant would not significantly increase the risk of 

any unreasonable adverse effect on the environment.” Unreasonable adverse effects on the 

environment are defined under Section 2(bb) of FIFRA as “... any unreasonable risk to man or 

the environment, taking into account the economic, social, and environmental costs and benefits 

of the use of any pesticide...” Thus, pursuant to Section 3(c)(7)(A), EPA may conditionally 

register a pesticide if (1) the pesticide and its proposed use are identical or substantially similar 

to a currently registered pesticide; or (2) the pesticide and its proposed use differ only in ways 

that would not significantly increase the risk of unreasonable adverse effects; and (3) approving 

the registration would not significantly increase the risk of any unreasonable adverse effect. 

In our registration decision for the 2010 growing season, we found that OAM1 and OAM RW 

met criteria (2) and (3) of Section 3(c)(7)(A) for a time-limited registration to expire September 

30, 2010. Optimum Acre Max (OAM) 1 is a seed blend consisting of two currently registered 

products, 90% Herculex Xtra and 10% Herculex I. Optimum Acre Max (OAM) RW is a seed 

blend consisting of an already registered product and non-PIP corn, 90% Herculex RW and 10% 

non-B.t. corn. Thus, both products were found to be substantially similar to already registered 

PIPs in composition and use site (field corn). These products did not meet criteria (1), however, 

because the proposed use of OAM1 and OAM RW that achieves the insect resistance 

management refuge via a seed mix rather than a block refuge is not substantially similar to any 

currently registered pesticide. Having the refuge in the bag of seeds is a novel approach. 

We determined, however, that each of these products met criteria (2) as, when used in 

accordance with the terms and conditions of the time-limited registration set to expire September 

30, 2010, neither would significantly increase the risk of unreasonable adverse effects on the 

environment. Since OAM1 and OAM RW are substantially similar to already registered PIPs in 

composition and use site, EPA’s consideration of whether these new products would 

significantly increase the risk of any unreasonable adverse effect on the environment was limited 

to the change in insect resistance management refuge deployment and percentage, i.e., a 10% 

seed blend in the bag versus a 20% block refuge. The unreasonable adverse effect of concern 

was the development of resistance to Cry34/35Ab1 in corn. Thus, we considered: (1) how does 

the registration of OAM1 and OAM RW contribute to the development of corn rootworm 
Optimum AcreMax B.t. Corn Seed Blends Page 18 of 54 

Biopesticides Registration Action Document

resistance to Cry34/35Ab1 corn; (2) should this resistance develop, what risk does it pose to man 

or the environment; and (3) taking into account the economic, social, and environmental costs 

and benefits, does this risk constitute an unreasonable adverse effect? 

The Risk of OAM1 and OAM RW Registrations Causing CRW Resistance to Cry34/35Ab1

The modeling used by EPA to assess IRM strategies utilizes comparative simulation models. 

The model durability output, years to resistance, is intended to be used for comparative purposes 

to evaluate different refuge options on a relative basis. The durability outputs that EPA 

determined for the proposed 90% CRW protected seed/10% non-CRW protected seed blend, and 

a 20% block refuge are 11.3 years to resistance, and 20.2 years to resistance, respectively. Thus, 

our analysis indicated that, as modeled, the proposed seed blend is 45% less durable on a 

comparative basis than the 20% block refuge currently required for single trait CRW PIPs . 

Besides the currently registered Pioneer PIPs, Cry34/35Ab1 corn is registered in a number of 

other B.t. corn PIPs, including multi-CRW B.t. toxin products, by Monsanto and Dow 

AgroSciences. Should resistance develop to Cry34/35 in a OAM1 seed blend, these other 

products could be adversely affected including potential loss of efficacy and viability as CRW 

control tools. We note, in particular, the recent statement of the National Research Council to 

the effect that “. . . results from simulation models and small-scale laboratory experiments 

indicate that the evolution of resistance to two-toxin cultivars is accelerated when plants that 

produce two B.t. toxins are grown near plants that produce just one toxin.” National Academy of 

Sciences, Impact of Genetically Engineered Crops on Farm Sustainability in the United States,

2-37 (2010). Based on our assessment, we concluded that significant acreage of a 10% seed 

blend with a single, non-high dose mode of action such as Cry 34/35Ab1 likely increases the risk 

of resistance for all B.t. corn products containing Cry34/35Ab1. But, the time-limited 

registration expiring September 30, 2010, likely would not increase the risk of resistance to 

Cry34/35Ab1. 

Pioneer projected that the time-limited registrations granted for the 2010 growing season would 

result in planting on only approximately 0.042% of acres of non-Red Zone geography corn acres; 

and only on approximately 0.077% of Red-Zone geography corn acres. In the context of 90 

million acres of corn planted in the United States annually, we concluded that plantings on such 

limited acreage would not have effects on CRW resistance development. 

The ad hoc members of the SAP commented that the evolution of resistance that occurs as a 

result of OAM1 presence in the field will speed resistance to Cry34/35 pyramided products. 

Comments from Dow Agrosciences and Syngenta also expressed concern that OAM1 would 

impact other PIP products and speed resistance evolution. CSPI commented that if the 

registration decision was based in part on sales projections, then acreage caps should be a term of 

the registration. We appreciate the concerns of the ad hoc members of the SAP, Dow 

Agrosciences, and Syngenta regarding the potential of OAM1 to accelerate evolution of 

resistance to Cry 34/35. This is a concern that we share. We took steps and imposed terms on 

the OAM1 registration for the 2010 growing season to address these concerns. Pioneer was 

required to implement an enhanced resistance monitoring plan for OAM1 that included 

benchmark studies showing susceptibility of the western corn rootworm populations (WCRW) in 

the Sublethal Seedling Assay. These studies must be submitted by December 1, 2010. Pioneer 

must attempt to obtain benchmark susceptibility data using the Sublethal Seedling Assay for the 

northern corn rootworm as well, and submit such studies by December 1, 2011. Pioneer must 
Optimum AcreMax B.t. Corn Seed Blends Page 19 of 54 

Biopesticides Registration Action Document

also submit by December 1, 2010, a detailed OAM1-specific resistance monitoring and remedial 

action plan, including an analysis to determine the expected field performance criteria for OAM1 

products so that unexpected damage can be benchmarked. This plan will be updated by 

December 1, 2012, if needed, based on continued field evaluation of OAM1 performance. 

Pioneer was also required to develop programs to evaluate whether there are statistically 

significant and biologically relevant changes in target insect susceptibility to Cry1F and 

Cry34Ab1/Cry35Ab1 proteins in the target insects; and a remedial action plan that must set forth 

the specific measures Pioneer will take in the event that any field-relevant insect resistance is 

detected. While we are not requiring specific acreage caps as part of the registration for 2011 

and 2012, we will closely monitor the extent of sales and plantings of OAM1, as well as all 

insect monitoring data. In the event there is any indication of resistance evolution, Pioneer must 

report that to EPA immediately. We will assess all data and information relevant to the 

indication of resistance evolution and, if we determine that such action is appropriate, will use 

our authority under Section 6(c) of FIFRA to suspend the registration. 

Should Resistance Develop, What Risk Does it Pose to Man or the Environment, and What 

Economic and Social Costs?

Should Cry34/35Ab1 resistance develop, there would be an increase in conventional chemical 

insecticide use for U.S. corn production. Although there are other CRW controlling PIPs in the 

marketplace and under development, Cry34/35Ab1 resistance would not only impact OAM1 and 

OAM RW, but also HERCULEX® RW, HERCULEX® XTRA, and GenuityTM SmartStaxTM. 

Increased use of conventional insecticides would increase impacts on the environment and man. 

There would also be indirect impacts in increased energy consumption for manufacture, 

transport, and application of chemical insecticides; increased waste streams arising from 

pesticide manufacture; and increased disposal of pesticide waste containers and residues from 

pesticide applications. 

What are the Economic, Social, and Environmental Benefits of OAM1 and OAM RW?

Both OAM1 and OAM RW have been determined by EPA to be efficacious in their control of 

corn rootworm. 

OAM1 and OAM RW should increase grower compliance with CRW refuge requirements by 

providing a novel and effective way of simplifying the refuge deployment process for growers as 

the corn rootworm refuge is deployed as a seed blend rather than a separate block in the field. 

OAM1 and OAM RW should also reduce the insecticide use in the CRW refuge and in the 

CRW-PIP fields. Currently, corn rootworm PIP products require insecticide treatment of the PIP 

acreage, even if economic thresholds are not reached. This use of insecticides solely to support 

the management of resistance has been required if aerial insecticides are applied to the refuge for 

control of CRW adults or if pests other than adult corn rootworms are treated with CRW-labeled 

insecticide on the refuge acres when adult corn rootworms are present. OAM1 and OAM RW 

would reduce this IRM based use of insecticides. Indirect benefits of decreased insecticide use 

include reduced energy consumption for manufacture, transport, and application of chemical 

insecticides; reduced waste streams arising from pesticide manufacture; reduced disposal of 

pesticide waste containers and residues from pesticide applications. OAM1 and OAM RW 

should benefit growers by simplifying the planting process. 

Corn Rootworm Refuge in the Bag Registration Decision for 2010 Growing Season
Optimum AcreMax B.t. Corn Seed Blends Page 20 of 54 

Biopesticides Registration Action Document

We concluded that OAM1 and OAM RW met the criteria for registration under FIFRA Section 

3(c)(7)(A). Our assessment supported the determination that these products are not likely to 

contribute towards the development of resistance of CRW to Cry34/35Ab1 during the period of 

the time-limited registration in effect for the 2010 growing season. Our assessment of the likely 

impacts concerning ease of use, increased grower compliance, efficacy, and reduced insecticide 

use coupled with our determination that OAM1 and OAM RW are not likely to increase the risk 

of resistance of CRW to Cry34/35Ab1 developing during the 2010 growing season supported the 

conclusion that the criteria under FIFRA Section 3(c)(7)(A) were met such that registration of 

OAM1 and OAM RW would not pose a risk of unreasonable adverse effects on the environment 

during this period. 

On October 1, 2009, EPA announced a new policy to provide a more meaningful opportunity for 

the public to participate on major registration decisions before they occur. According to this new 

policy, EPA intends to provide a public comment period prior to making a registration decision 

for, at minimum, the following types of applications: new active ingredients; first food use; first 

outdoor use; first residential use; and other actions for which the Agency anticipates that there 

will be significant public interest. 

Notwithstanding that the current actions on OAM1 and OAM RW qualify as "actions for which 

the Agency anticipates that there will be significant public interest," EPA believed that it was in 

the best interests of the public and the environment to issue the registrations for OAM1 and 

OAM RW without delay. The PRIA (Pesticide Registration Improvement Act) deadline date of 

May 1, 2010, was sufficiently late in the growing season that a 30-day delay would have 

lessened the likelihood that significant acreage of these products could be planted in 2010. 

Given the potential benefits attendant to the blended refuge concept, EPA concluded that it was 

in the best interests of the public and the environment to issue the registrations for OAM1 and 

OAM RW without delay for 2010 growing season. The registration is only effective for the 

current growing season. Therefore, consistent with the Agency’s policy for making certain 

registration actions more transparent, EPA issued these time-limited registrations with an initial 

period to expire September 30, 2010, and, concurrent with their issuance, provided a 30-day 

public comment period on the time-limited registrations. EPA registered this product as a timelimited registration, with the understanding that public comments could bring to light new 

information or concerns that could inform EPA’s initial decision. Any subsequent action taken 

on these registrations will be informed by any information received during the public comment 

period. 

CSPI commented that the public participation process for the OAM1 registration for the 2010 

growing season was inadequate. CSPI believed that the opportunity for public comment should 

have occurred prior to the registration decision. We do not disagree with the comment. All 

things being equal, however, we felt that it was important to meet the PRIA due date for this 

action, and that taking public comment concurrent with the registration would not unfairly 

deprive the public of the opportunity for meaningful comment, nor deprive us of the benefit of 

public input. The OAM1 2010 registration was a very short, approximately five-month, time 

limited registration that was only good for one growing season. Moreover, as noted in the April 

30, 2010, BRAD, the timing of the registration was so late in the growing season that it 

precluded significant sale and planting of the product. As it happened, data submitted by Pioneer 

(Rood, 2010), verified that OAM1 acres for 2010 amounted to only 39,000 acres, which is less 

than projected in the earlier BRAD. We are pleased that we did receive meaningful comment on 
Optimum AcreMax B.t. Corn Seed Blends Page 21 of 54 

Biopesticides Registration Action Document

the April 30, 2010, registration action, and that that comment has been useful in informing the 

preliminary decision that we are announcing today. The OAM1 registration that we are 

proposing today contains a number of enhanced requirements for corn rootworm resistance 

management that we believe will have a propitious impact not only on this registration, but on 

other B.t. corn registrations as well. Finally, comments received on the OAM1 registration 

played a significant role in EPA's deliberations on the concept of tiered time-limited 

registrations. As discussed below, we believe that it makes sense to make a specific connection 

between the risk of resistance evolving that a particular product presents and the time permitted 

for the registration of that product to be in effect. Products that we determine through scientific 

evaluation to meet a stringent standard for protecting against the risk of resistance evolving will 

be eligible for a registration of up to fifteen years. CSPI also commented that EPA "stealthily" 

released the OAM1 BRAD, and did not announce the comment period either in the Federal 

Register or by press release. We can assure all concerned that the intent was not to be "stealthy." 

 EPA opened the public comment period for this action as it has done for all other actions subject 

to the new public participation initiative, i.e., by announcing the comment period on the 

Agency's public participation webpage. This comment points out to us, however, that there are 

instances where more extensive efforts to publicize the initiation of a comment period and the 

availability of BRADs, etc., may be warranted. We undertook such efforts in conjunction with 

the B.t. corn registrations comment period. 

B. Corn Rootworm Refuge in the Bag Registration Decision for 2011 and 2012 

Growing Seasons 

In the April 30, 2010 BRAD, we preliminarily concluded that our modeling analysis combined 

with the Pioneer sales projections for the 2011 and 2012 growing seasons supported continued 

registration of OAM1 and OAM RW for 2011 and 2012. We noted that Pioneer predicts OAM1 

and OAM RW acreage to increase up to 8% of the Red Zone and 12% of the non-Red Zone. 

EPA invited comments during the 30-day comment period on the preliminary decision to register 

OAM1 and OAM RW for the 2011-2012 growing seasons. Important to this preliminary 

decision was the fact that Pioneer committed to additional elements that would enhance the IRM 

plan applicable to OAM1 and OAM RW regarding insect resistance monitoring and remedial 

action should resistance be detected, and the refuge assurance program. These were listed in 

detail in the terms and conditions of the April 30, 2010, OAM1 and OAM RW registrations. 

Section 3(c)(7)(A) of FIFRA provides for the registration or amendment of a pesticide when the 

pesticide and proposed use “...are identical or substantially similar to any currently registered 

pesticide and use thereof, or differ only in ways that would not significantly increase the risk of 

unreasonable adverse effects on the environment, and (ii) approving the registration or 

amendment in the manner proposed by the applicant would not significantly increase the risk of 

any unreasonable adverse effect on the environment.” Unreasonable adverse effects on the 

environment are defined under section 2(bb) of FIFRA as “... any unreasonable risk to man or 

the environment, taking into account the economic, social, and environmental costs and benefits 

of the use of any pesticide...” Thus, pursuant to section 3(c)(7)(A), EPA may conditionally 

register a pesticide if (1) the pesticide and its proposed use are identical or substantially similar 

to a currently registered pesticide; or (2) the pesticide and its proposed use differ only in ways 

that would not significantly increase the risk of unreasonable adverse effects; and (3) approving 

the registration would not significantly increase the risk of any unreasonable adverse effect. 

The Agency concludes that the following Cry34/35Ab1 corn product registrations, set to expire 
Optimum AcreMax B.t. Corn Seed Blends Page 22 of 54 

Biopesticides Registration Action Document

September 30, 2010, and described in-depth throughout this BRAD, meet both criteria (1) and 

(2): 

 (1) Optimum® AcreMaxTM 1 (OAM1) => Seed Blend of 90% HERCULEX® XTRA 

 and 10% HERCULEX® I 

 (2) OAM RW => Seed Blend of 90% HERCULEX® RW and 10% Non-B.t. Corn 

Each of these Cry34/35Ab1 corn products are identical in both composition and use (field corn) 

to plant-incorporated protectants that are currently registered. Thus, criterion (1) has been 

fulfilled. With regard to criterion (2), the Agency maintains, as was previously determined for 

the original registration of these particular products, that cultivation of Cry34/35Ab1-containing 

corn will not cause unreasonable adverse effects on the environment. The conditional 

environmental effects data, submitted in response to terms and conditions of registration and 

summarized in section II(C)(2)(b) of this BRAD, strengthen the Agency’s initial position and 

also confirm that long-term effects on non-target organisms are not anticipated. Lastly, the 

continued use of these products will likely still provide many of the benefits as were evaluated to 

support the OAM1 registration for the 2010 growing season (e.g., reduction in use of 

conventional insecticides that are highly toxic to both humans and the environment; increased 

compliance with CRW refuge requirements). 

In conclusion, as the expiring Cry34/35Ab1 products (Optimum® AcreMaxTM 1 (OAM1) => 

Seed Blend of 90% HERCULEX® XTRA and 10% HERCULEX® I; and OAM RW => Seed 

Blend of 90% HERCULEX® RW and 10% Non-B.t. Corn) have met the required criteria under 

section 3(c)(7)(A) of FIFRA, the Agency has amended these registrations to extend their 

respective expiration dates as follows: 

Product Name (EPA Reg. No.) Proposed Expiration Date 

OAM1 (29964-6) September 30, 2012 

OAM1 RW (29964-10) September 30, 2012 

Although data provided were satisfactory to make the determinations required by section 

3(c)(7)(A) of FIFRA, they were not sufficient to support an unconditional registration under 

FIFRA section 3(c)(5). Additional data, specifically in relation to insect resistance management 

are necessary for a finding of registrability under FIFRA section 3(c)(5) and remain as terms or 

conditions for the purposes of the proposed amendments. 

C. European Corn Borer and Southwestern Corn Borer Refuge in the Bag Registration 

Decision for the 2011 Growing Season

Section 3(c)(7)(A) of FIFRA provides for the registration or amendment of a pesticide when the 

pesticide and proposed use “...are identical or substantially similar to any currently registered 

pesticide and use thereof, or differ only in ways that would not significantly increase the risk of 

unreasonable adverse effects on the environment, and (ii) approving the registration or 

amendment in the manner proposed by the applicant would not significantly increase the risk of 

any unreasonable adverse effect on the environment.” Unreasonable adverse effects on the 

environment are defined under section 2(bb) of FIFRA as “... any unreasonable risk to man or 

the environment, taking into account the economic, social, and environmental costs and benefits 
Optimum AcreMax B.t. Corn Seed Blends Page 23 of 54 

Biopesticides Registration Action Document

of the use of any pesticide...” Thus, pursuant to section 3(c)(7)(A), EPA may conditionally 

register a pesticide if (1) the pesticide and its proposed use are identical or substantially similar 

to a currently registered pesticide; or (2) the pesticide and its proposed use differ only in ways 

that would not significantly increase the risk of unreasonable adverse effects; and (3) approving 

the registration would not significantly increase the risk of any unreasonable adverse effect. 

The Agency concludes that the following Bt corn seed blend product registrations, set to expire 

September 1, 2011, and described in-depth throughout this BRAD, meet both criteria (1) and (2): 

Optimum® AcreMaxTM Xtra Insect Protection contains a seed blend with 90% 

1507xMON810x59122 (Cry1Ab x Cry34/35Ab1 x Cry1F) and 10% Non-B.t. Corn. 

Optimum® AcreMaxTM Insect Protection contains a seed blend with 95% Optimum® 

IntrasectTM (Cry1Ab x Cry1F) and 5% Non-B.t. Corn. 

Each of these corn products are identical in both composition and use (field corn) to plantincorporated protectants that are currently registered. Thus, criterion (1) has been fulfilled. With 

regard to criterion (2), the Agency maintains that cultivation of the two toxin lepidopteran seed 

blend corn will not cause unreasonable adverse effects on the environment. In regards to 

criterion (3), although the Agency has determined that a seed blend refuge for lepidopteran pests 

may present a greater risk of resistance than a comparable block refuge, this risk is not 

unreasonable under FIFRA. This is because the durability of seed blends for AOM (pyramided 

products) are expected to be higher than a 20% block refuge for single toxin Bt corn PIPs. 

Lastly, the use of these products will provide benefits by increasing compliance with refuge 

requirements and possibly further reducing conventional pesticide use (block refuges are 

frequently treated to economically manage pests whereas seed blend refuges are not 

independently treated). 

Product Name (EPA Reg. No.) Expiration Date 

OAM (29964-12) September 1, 2011 

OAM Xtra (29964-11) September 1, 2011 

Although data provided were satisfactory to make the determinations required by section 

3(c)(7)(A) of FIFRA, they were not sufficient to support an unconditional registration under 

FIFRA section 3(c)(5). Additional data, specifically in relation to insect resistance management 

are necessary for a finding of registrability under FIFRA section 3(c)(5) and remain as terms or 

conditions for the purposes of the proposed amendments. 

V. TERMS and CONDITIONS for NEW ECB SEED BLENDS 

OAM; EPA Registration Number 29964-12

 

This product is conditionally registered in accordance with FIFRA Section 3(c)(7)(A) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended, provided that you do 

 the following terms and conditions. 
Optimum AcreMax B.t. Corn Seed Blends Page 24 of 54 

Biopesticides Registration Action Document

1] The subject registration will automatically expire on midnight September 1, 2011. 

2] The subject registration will be limited to a seed mix of TC1507 (Cry1F) x Cry1Ab corn seed 

blended with not less than 5% non-Bt corn seed. 

3] Submit/cite all data required for registration of your product under FIFRA § 3(c)(5) when the 

Agency requires registrants of similar products to submit such data. 

4] This plant-incorporated protectant may be combined through conventional breeding with other 

registered plant-incorporated protectants that are similarly approved for use in combination, 

through conventional breeding, with other registered plant-incorporated protectants to produce 

inbred corn lines and hybrid corn varieties with combined pesticidal traits. 

5] Submit or cite all data required to support Optimum® IntrasectTM within the timeframes 

required by the terms and conditions of EPA Registration Number 29964-7. 

6] The following seed blend related IRM data is being required to support a longer term analysis 

of the potential for insect resistance developing from the use of two toxin based Bt corn seed 

blends targeting European corn borer and southwestern corn borer. Provided the registration 

expiration date is extended, submit an interim report on the following data within one year and a 

final report within two years. 

d) Ovipositional behavior in seed blends under, for example, increased pest pressure; 

e) The potential and degree of crowding out refuge plants by Bt protected plants in 

blends expressing corn rootworm traits under different environmental 

conditions and higher pest pressure; 

f) Adult movement (related to mating and movement from refuges), larval movement, 

larval feeding (i.e., selective feeding within corn ears or on pollen), survival of 

heterozygote genotypes on OAM (markers may need to be determined for heterozygotes), 

and the potential for epistatic mechanisms of resistance (particularly with older instars).

7] In order to improve the strength of modeling, you must incorporate the following into your 

model and clarify certain assumptions utilized within 120 days of the date of this registration: 

g) Non-uniform oviposition for both generations of lepidoptera in a 10% seed blend (OAM 

); 

h) Non-uniform oviposition for the second generation of lepidoptera in a 5% seed blend 

without a corn rootworm trait; and 

i) Increased female (SWCB) pre-ovipositional dispersal out of seed blends. 

j) How was fecundity increased in seed blends? Does the 6-fold (and 4-fold) increase refer 

to the fecundity of susceptible insects on refuge plants relative to fecundity on Bt plants? 

k) How was uniform oviposition dealt with in the model code? The methodology should be 

explained. Do adults form one big random mating pool in seed blends, and eggs are 

uniformly applied across the field (or else)? 

l) How was non-uniform oviposition dealt with in the model code of the sensitivity 

analysis? Pioneer/DuPont should explain the methodology used. 

8] Pioneer must implement the following Insect Resistance Management Program: 
Optimum AcreMax B.t. Corn Seed Blends Page 25 of 54 

Biopesticides Registration Action Document

The required IRM program for OAM corn must have the following elements: 

Requirements relating to creation of a lepidopteran refuge (consisting of corn that does not 

contain any Bt trait for lepidopteran control) in cotton growing regions in conjunction with the 

planting of any acreage of OAM corn; 

Requirements for Pioneer to prepare and require OAM users to sign “grower agreements,” that 

impose binding contractual obligation on the grower to comply with the refuge requirements; 

Requirements regarding programs to educate growers about IRM requirements; 

Requirements regarding programs to evaluate and promote growers’ compliance with IRM 

requirements; 

Requirements regarding programs to evaluate whether there are statistically significant and 

biologically relevant changes in target insect susceptibility to Cry1Ab and Cry1F proteins in the 

target insects; 

Requirements regarding a “remedial action plan,” that contains measures Pioneer would take in 

the event that any field-relevant insect resistance was detected as well as to report on activity 

under the plan to EPA; 

Annual reports on units sold by state (units sold by county level will be made available to the 

Agency upon request), IRM grower agreements results, and the compliance assurance program 

including the educational program on or before January 31st of each year, beginning in 2011. 

a) Refuge requirements for OAM 

Corn-Belt/Non-Cotton Growing Areas 

Optimum® AcreMaxTM Xtra Insect Protection contains a Lepidopteran and corn rootworm refuge 

that is “in the bag” and is automatically implemented when the grower plants the product. No 

additional refuge is required when planting this product. 

Foliar insecticide treatments for control of European corn borer, corn earworm, southwestern 

corn borer, fall armyworm, black cutworm, western bean cutworm, lesser corn stalk borer, 

southern corn stalk borer, and sugarcane borer may be applied only if economic thresholds are 

reached for one or more of these target pests. Foliar insecticide treatments are also permitted for 

control of corn rootworm adults if economic thresholds are reached. Economic thresholds will 

be determined using methods recommended by local or regional professionals (e.g., Extension 

Service agents, crop consultants). 

Cotton-Growing Region Refuge Requirements 

In cotton-growing regions where corn earworm is a significant pest: 

 The 20% refuge must be planted with non-Bt corn hybrids. 

 Optimum® AcreMaxTM and the 20% non-Bt refuge should be sown on the same day, or with 

the shortest window possible between planting dates 
Optimum AcreMax B.t. Corn Seed Blends Page 26 of 54 

Biopesticides Registration Action Document

 External refuges may be planted as an in-field or adjacent (e.g., across the road) refuge or as 

a separate block within 1/2 mile of the Optimum® AcreMaxTM corn field. 

 In field refuge options include: blocks, perimeter strips (i.e., along the edges or headlands), 

or in-field strips. 

 When planting the refuge in strips across the field, refuges must be at one (1) row wide. 

 Insecticide treatments for control of European corn borer, corn earworm, southwestern corn 

borer, fall armyworm, black cutworm, western bean cutworm, lesser corn stalk borer, 

southern corn stalk borer, and sugarcane borer may be applied only if economic thresholds 

are reached for one or more of these target pests. In addition, the refuge can be protected 

from CRW damage by an appropriate seed treatment or soil insecticide; however, 

insecticides labeled for adult CRW control must be avoided in the refuge during the period of 

CRW adult emergence. Economic thresholds will be determined using methods 

recommended by local or regional professionals (e.g., Extension Service agents, crop 

consultants). Microbial Bt insecticides must not be applied to non-Bt corn refuge plants. 

 Cotton-growing areas include the following states: Alabama, Arkansas, Georgia, Florida, 

Louisiana, North Carolina, Mississippi, South Carolina, Oklahoma (only the counties of 

Beckham, Caddo, Comanche, Custer, Greer, Harmon, Jackson, Kay, Kiowa, Tillman, 

Washita), Tennessee (only the counties of Carroll, Chester, Crockett, Dyer, Fayette, Franklin, 

Gibson, Hardeman, Hardin, Haywood, Lake, Lauderdale, Lincoln, Madison, Obion, 

Rutherford, Shelby, and Tipton), Texas (except the counties of Carson, Dallam, Hansford, 

Hartley, Hutchinson, Lipscomb, Moore, Ochiltree, Roberts, and Sherman), Virginia (only the 

counties of Dinwiddie, Franklin City, Greensville, Isle of Wight, Northampton, 

Southampton, Suffolk City, Surrey, Sussex) and Missouri (only the counties of Dunklin, New 

Madrid, Pemiscot, Scott, Stoddard). 

These refuge requirements do not apply to seed propagation of inbred and hybrid corn seed corn 

up to a total of 20,000 acres per county and up to a combined U.S. total of 250,000 acres per PIP 

active ingredient per registrant per year. 

When on-farm assessments identify non-compliance with refuge requirements for one or more Bt

corn products, additional educational material and assistance are provided by the registrant to 

help these growers meet the refuge requirements across their farming operations. 

b) Grower Agreement for OAM Corn 

1. Persons purchasing OAM corn must sign a grower agreement. The term “grower 

agreement” refers to any grower purchase contract, license agreement, or similar 

legal document. 

2. The grower agreement and/or specific stewardship documents referenced in the 

grower agreement must clearly set forth the terms of the current IRM program. 

By signing the grower agreement, a grower must be contractually bound to 

comply with the requirements of the IRM program. 

3. Pioneer must implement a system equivalent to what is already approved for 

previously registered Pioneer Bt corn products, which is reasonably likely to 

assure that persons purchasing OAM corn will affirm annually that they are 

contractually bound to comply with the requirements of the IRM program. A 

description of the system must be submitted to EPA within 90 days from the date 
Optimum AcreMax B.t. Corn Seed Blends Page 27 of 54 

Biopesticides Registration Action Document

of registration. (This information has been submitted and is being evaluated by 

the Agency.) 

4. Pioneer must use a grower agreement and must submit to EPA, within 90 days 

from the date of registration, a copy of that agreement and any specific 

stewardship documents referenced in the grower agreement. (This information 

has been submitted and is being evaluated by the Agency.)If Pioneer wishes to 

change any part of the grower agreement or any specific stewardship documents 

referenced in the grower agreement that would affect either the content of the 

IRM program or the legal enforceability of the provisions of the agreement 

relating to the IRM program, 30 days prior to implementing a proposed change, 

Pioneer must submit to EPA the text of such changes to ensure it is consistent 

with the terms and conditions of this registration. 

5. Pioneer shall maintain records of all OAM corn grower agreements for a period 

of three years from December 31st of the year in which the agreement was signed. 

6. Beginning on January 31, 2012, and annually thereafter, Pioneer shall provide 

EPA with a report on the number of units of OAM corn seed shipped and not 

returned, and the number of such units that were sold to persons who have signed 

grower agreements. The report shall cover the time frame of a twelve-month 

period. Note: The first report shall contain the specified information from the 

time frame starting with the date of registration and extending through the 2011 

growing season. 

7. Pioneer must allow a review of the grower agreements and grower agreement 

records by EPA or by a State pesticide regulatory agency if the State agency can 

demonstrate that confidential business information, including names, personal 

information, and grower license number, will be protected. 

c) IRM Education and IRM Compliance Monitoring Program for OAM Corn 

1. Pioneer must design and implement a comprehensive, ongoing IRM education 

program designed to convey to OAM corn users the importance of complying 

with the IRM program. The program must also address unexpected pest damage 

and guidance for growers in this area. The education program shall involve the 

use of multiple media, e.g. face-to-face meetings, mailing written materials, EPAreviewed language on IRM requirements on the bag or bag tag, and electronic 

communications such as by internet, radio, or television commercials. Copies of 

the materials will be provided to EPA for their records. The program shall 

involve at least one written communication annually to each OAM corn user 

separate from the grower technical guide. The communication shall inform the 

user of the current IRM requirements and specifically the need to plant a 

lepidopteran refuge in cotton growing regions. Pioneer shall coordinate its 

education program with the educational efforts of other registrants and other 

organizations, such as the National Corn Growers Association and state extension 

programs. 

2. Pioneer must design and immediately implement a “bag tag” that will be attached 
Optimum AcreMax B.t. Corn Seed Blends Page 28 of 54 

Biopesticides Registration Action Document

to all bags of OAM seed sold and delivered for the 2011 growing season and 

annually thereafter. The purpose of this bag tag is to remind growers that OAM 

products require a separate 20% lepidopteran refuge in cotton-growing areas. The PIP 

product label accepted by EPA must include how this information will be conveyed 

to growers via text and graphics. A revised PIP product label must be submitted by 

January 31, 2011. 

3. Pioneer must conduct targeted, on-farm compliance assessments for growers who 

purchase OAM seed to ensure growers are compliant with the requirement of a 20% 

refuge for lepidopteran pests in cotton growing areas. For the 2011 growing season 

and thereafter, Pioneer must conduct on-farm assessments or roughly half the number 

of assessments that Pioneer will contribute to the 2011 Agricultural Biotechnology 

Stewardship Technical Committee (ABSTC) compliance assurance program 

assessment for corn borer and stacked products. Pioneer must contract with an 

independent third party to conduct these compliance assessments. The table below 

reflects the relative number of on-farm assessments for OAM based on Pioneer’s 

contribution to the ABSTC compliance assurance program report and is subject to 

change with time as appropriate. 

i. A third party is classified as a party other than the registrant, the grower, or anyone 

else with a direct interest in IRM compliance for Bt corn. 

Pioneer must provide a report to EPA summarizing the OAM compliance assurance 

program activities and results for the prior year and plans for the OAM compliance 

assurance program for the current year, by January 31, 2012, and annually thereafter. 

Within one month of submitting this report to EPA, the registrant shall meet with EPA to 

discuss its findings. The report must inform EPA of the number of growers deemed 

ineligible to purchase Bt corn seed on the basis of continued non-compliance with the 

insect resistance management refuge requirements. 

4. Annually, Pioneer shall revise, and expand as necessary, its education program to take 

into account the information collected through the compliance survey and from other 

sources. The changes shall address aspects of grower compliance that are not sufficiently 

high. 

5. Beginning January 31, 2012, Pioneer must provide a report to EPA summarizing the 

activities it carried out under its education program for the prior year. Annually 

thereafter, Pioneer must provide EPA any substantive changes to its grower education 

activities as part of the overall IRM compliance assurance program report. Pioneer must 

either submit a separate report or contribute to the report from the industry working 

group, ABSTC. 

6. The registrant shall revise and expand its existing Compliance Assurance Program to 

include the following elements. The registrant must prepare and submit by January 31, 

2012, a written description of its revised Compliance Assurance Program. The registrant 

may coordinate with other registrants in designing and implementing its Compliance 

Assurance Program. 
Optimum AcreMax B.t. Corn Seed Blends Page 29 of 54 

Biopesticides Registration Action Document

7. The registrant will enhance the refuge education program throughout the seed delivery 

channel: 

i. Ensure sales representatives, licensees, seed dealers, and growers recognize the 

importance of correct refuge implementation and potential consequences of failure to 

plant the required refuge; 

ii. Pioneer must design and immediately implement a “bag tag” that will be attached to all 

bags of OAM seed sold and delivered for the 2011 growing season and annually 

thereafter. The purpose of this bag tag is to remind growers that OAM products require 

a separate 20% lepidopteran refuge in cotton growing areas. The PIP product label 

accepted by EPA must include how this information will be conveyed to growers via text 

and graphics. A revised PIP product label must be submitted by January 31, 2011. 

8. The registrant will focus the majority of on-farm assessments on regions with the 

greatest risks for resistance: 

i. Use Bt corn adoption, pest pressure information, and other available information to 

identify regions where the risk of resistance is greatest; 

ii. Focus approximately two-thirds of on-farm assessments on these regions, with the 

remaining assessments conducted across other regions where the product is used. 

9. The registrant will use its available Bt sales records and other information to refine 

grower lists for on-farm assessments of their compliance with refuge requirement: 

i. Identify for potential on-farm assessment growers whose sales information indicates 

they have purchased the Bt corn product but may have purchased little or no refuge seed 

from the registrant, licensee, or affiliated company. 

10. The registrant will contract with third parties to perform on-farm assessments of 

compliance with refuge requirements: 

i. The third-party assessors will conduct all first-time on-farm assessments as well as 

second-year on-farm assessments of those growers found out of compliance in a firsttime assessment 

11. The registrant will annually refine the on-farm assessment program for the Bt corn 

product to reflect the adoption rate and level of refuge compliance for the product. 

12. The registrant will follow up with growers who have been found significantly out of 

compliance under the on-farm assessment program and are found to be back in 

compliance the following year: 

i. All growers found to be significantly out of compliance in a prior year will annually be 

sent additional refuge assistance information for a minimum of two years by the 

registrant, seed supplier, or third party assessor, after completing the assessment process; 
Optimum AcreMax B.t. Corn Seed Blends Page 30 of 54 

Biopesticides Registration Action Document

ii. The registrant will conduct follow-up checks on growers found to be significantly out 

of compliance within three years after they are found to be back in compliance; 

iii. A grower found with a second incident of significant non-compliance with refuge 

requirements for the Bt corn product within a five-year period will be denied access to 

Pioneer Hi-Bred’s Bt corn products the next year. Similarly, seed dealers who are not 

fulfilling their obligations to inform/educate growers of their IRM obligations will lose their 

opportunity to sell Bt corn. 

d) Insect Resistance Monitoring and Remedial Action Plan for OAM Corn 

The Agency is imposing the following conditions for this lepidopteran toxin: 

The registrant will monitor for resistance to its lepidopteran-resistant Bt corn. The monitoring 

program shall consist of two approaches: (1) focused population sampling and laboratory testing; 

and (2) investigation of reports of less-than expected control of labeled insects. Should fieldrelevant resistance be confirmed, an appropriate resistance management action plan will be 

implemented. 

(1) Focused Population Sampling 

The registrant shall annually sample and bioassay populations of the key target pests Ostrinia 

nubilalis (European corn borer; ECB), Diatraea grandiosella (Southwestern corn borer; S 

WCB), and Helicoverpa zea (corn earworm; CEW). Sampling for the target pests will be focused 

in areas identified as those with the highest risk of resistance development (e.g., where 

lepidopteran-active Bt hybrids are planted on a high proportion of the corn acres, and where the 

insect species are regarded as key pests of corn). Bioassay methods must be appropriate for the 

goal of detecting field-relevant shifts in population response to lepidopteran resistant Bt corn 

and/or changes in resistance allele frequency in response to the use of Bt corn and, as far as 

possible, should be consistent across sampling years to enable comparisons with historical data. 

The number of populations to be collected shall reflect the regional importance of the insect 

species as a pest, and specific collection regions will be identified for each pest. For ECB, a 

minimum of 12 populations across the sampling region will be targeted for collection at each 

annual sampling. For SWCB, the target will be a minimum of six populations. For CEW, the 

target will be a minimum of 10 populations. Pest populations should be collected from multiple 

corn-growing states reflective of different geographies and agronomic conditions. To obtain 

sufficient sensitivity to detect resistance alleles before they become common enough to cause 

measurable field damage, each population collection shall attempt to target 400 insect genomes 

(egg masses, larvae, mated females, and/or mixed-sex adults), but a successful population 

collection will contain a minimum of 100 genomes. It is recognized that it may not be possible to 

collect the target number of insect populations or genomes due to factors such as natural 

fluctuations in pest density, environmental conditions, and area-wide pest suppression. 

The sampling program and geographic range of collections may be modified as appropriate 

based on changes in pest importance and for the adoption levels of lepidopteran-resistant Bt corn. 

The Agency shall be consulted prior to the implementation of such modifications. 
Optimum AcreMax B.t. Corn Seed Blends Page 31 of 54 

Biopesticides Registration Action Document

The registrant will report to the Agency before August 31 each year the results of the population 

sampling and bioassay monitoring program. 

Any incidence of unusually low sensitivity to the Bt protein in bioassays shall be investigated as 

soon as possible to understand any field relevance of such a finding. Such investigations shall 

proceed in a stepwise manner until the field relevance can be either confirmed or refuted, and 

results of these shall be reported to the Agency annually before August 31. The investigative 

steps will include: 

1. Re-test progeny of the collected population to determine whether the unusual bioassay 

response is reproducible and heritable. If it is not reproducible and heritable, no further action is 

required. 

2. If the unusual response is reproducible and heritable, progeny of insects that survive the 

diagnostic concentration will be tested using methods that are representative of exposure to Bt

corn hybrids under field conditions. If progeny do not survive to adulthood, any suspected 

resistance is not field relevant and no further action is required. 

3. If insects survive steps 1 and 2, resistance is confirmed, and further steps will be taken to 

evaluate the resistance. These steps may include: 

 determining the nature of the resistance (i.e., recessive or dominant, and the level 

of functional dominance); 

 estimating the resistance-allele frequency in the original population; 

 determining whether the resistance-allele Frequency is increasing by analyzing field 

collections in subsequent years sampled from the same site where the resistance allele(s) 

was originally collected; 

 determining the geographic distribution of the resistance allele by analyzing field 

collections in subsequent years from sites surrounding the site where the resistance 

allele(s) was originally collected. 

Should field-relevant resistance be confirmed, and the resistance appears to be increasing or 

spreading, the registrant will consult with the Agency to develop and implement a case-specific 

resistance management action plan. 

(2) Investigation of Reports of Unexpected Levels of Damage by the Target 

Pests: 

The registrant will follow up on grower, extension specialist or consultant reports of unexpected 

levels of damage by the lepidopteran pests listed on the pesticide label. The registrant will 

instruct its customers to contact them if such incidents occur. The registrant will investigate all 

legitimate reports submitted to the company or the company's representatives. 

If reports of unexpected levels of damage lead to the suspicion of resistance in any of the key 

target pests (ECB, SWCB, and CEW), the registrant will implement the actions described below, 

based on the following definitions of suspected resistance and confirmed resistance. 
Optimum AcreMax B.t. Corn Seed Blends Page 32 of 54 

Biopesticides Registration Action Document

Suspected resistance

EPA defines suspected resistance to mean field reports of unexpected levels of insect feeding 

damage for which: 

 the corn in question has been confirmed to be lepidopteran-active Bt corn; 

 the seed used had the proper percentage of corn expressing Bt protein; 

 the relevant plant tissues are expressing the expected level of Bt protein; and 

 it has been ruled out that species not susceptible to the protein could be responsible for 

the damage, that no climatic or cultural reasons could be responsible for the damage, and 

that that there could be no other reasonable causes for the damage. 

The Agency does not interpret suspected resistance to mean grower reports of possible control 

failures or suspicious results from annual insect monitoring assays, nor does the Agency intend 

that extensive field studies and testing be undertaken to confirm scientifically the presence of 

insects resistant to Bt corn in commercial production fields before responsive measures are 

undertaken. 

If resistance is suspected, the registrant will instruct growers to do the following: 

 Use alternative control measures in the Bt corn fields in the affected region to control the 

target pest during the immediate growing season. 

 Destroy Bt corn crop residues in the affected region within one month after harvest with a 

technique appropriate for local production practices to minimize the possibility of 

resistant insects over-wintering and contributing to the next season's target pest 

population. 

Additionally, if possible, and prior to the application of alternative control measures or 

destruction of crop residue, the registrant will collect samples of the insect population in the 

affected fields for laboratory rearing and testing. Such rearing and testing shall be conducted as 

expeditiously as practical. 

Confirmed resistance 

EPA defines confirmed resistance to mean, in the case of field reports of unexpected levels of 

damage from the key target pests, that all the following criteria are met: 

 There is >30% insect survival and commensurate insect feeding in a bioassay, initiated 

with neonate larvae, that uses methods that are representative of exposure to Bt corn 

hybrids under field conditions (ECB and SWCB only). 

 In standardized laboratory bioassays using diagnostic concentrations of the Bt protein 

suited to the target pest in question, the pest exhibits resistance that has a genetic basis 

and the level of survivorship indicates that there may be a resistance allele frequency of ≥

0.1 in the sampled population. 
Optimum AcreMax B.t. Corn Seed Blends Page 33 of 54 

Biopesticides Registration Action Document

 In standardized laboratory bioassays, the LC50 exceeds the upper limit of the 95% 

confidence interval of the LC50 for susceptible populations surveyed both in the original 

baselines developed for this pest species and in previous years of field monitoring. 

(3) Response to Confirmed Resistance in a Key Target Pest as the Cause of Unexpected 

Levels of Damage in the Field 

When field resistance is confirmed (as defined above), the following steps will be taken by the 

registrant: 

 EPA will receive notification within 30 days of resistance confirmation; 

 Affected customers and extension agents will be notified about confirmed resistance 

within 30 days; 

 Monitoring will be increased in the affected area and local target pest populations will be 

sampled annually to determine the extent and impact of resistance; 

 If appropriate (depending on the resistant pest species, the extent of resistance, the timing 

of resistance, and the nature of resistance, and the availability of suitable alternative 

control measures), alternative control measures will be employed to reduce or control 

target pest populations in the affected area. Alternative control measures may include 

advising customers and extension agents in the affected area to incorporate crop residues 

into the soil following harvest to minimize the possibility of over-wintering insects, 

and/or applications of chemical insecticides; 

 Unless otherwise agreed with EPA, stop sale and distribution of the relevant 

lepidopteran-active Bt corn hybrids in the affected area immediately until an effective 

local mitigation plan approved by EPA has been implemented; 

 The registrant will develop a case-specific resistance management action plan within 90 

days according to the characteristics of the resistance event and local agronomic needs. 

The registrant will consult with appropriate stakeholders in the development of the action 

plan, and the details of such a plan shall be approved by EPA prior to implementation; 

 Notify affected parties (e.g. growers, consultants, extension agents, seed distributors, 

university cooperators and state/federal authorities as appropriate) in the region of the 

resistance situation and approved action plan; and 

 In subsequent growing seasons, maintain sales suspension and alternative resistance 

management strategies in the affected region(s) for the Bt corn hybrids that are affected 

by the resistant population until an EPA-approved local resistance management plan is in 

place to mitigate the resistance. 

A report on results of resistance monitoring and investigations of damage reports must be 

submitted to the Agency annually by August 31st each year for the duration of the conditional 

registration. 
Optimum AcreMax B.t. Corn Seed Blends Page 34 of 54 

Biopesticides Registration Action Document

e) Remedial Action Plan for lepidopteran pests and OAM Corn 

When field resistance is confirmed (as previously defined), the following steps will be taken by 

the registrant: 

• EPA will receive notification within 30 days of resistance confirmation; 

• Affected customers and extension agents will be notified about confirmed resistance 

within 30 days; 

• Monitoring will be increased in the affected area and local target pest populations will be 

sampled annually to determine the extent and impact of resistance; 

• If appropriate (depending on the resistant pest species, the extent of resistance, the timing of 

resistance, and the nature of resistance, and the availability of suitable alternative control 

measures) , alternative control measures will be employed to reduce or control target pest 

populations in the affected area. Alternative control measures may include advising customers 

and extension agents in the affected area to incorporate crop residues into the soil following 

harvest to minimize the possibility of over-wintering insects, and/or applications of chemical 

insecticides; 

• Unless otherwise agreed with EPA, stop sale and distribution of the relevant lepidopteranactive Bt corn hybrids in the affected area immediately until an effective local mitigation plan 

approved by EPA has been implemented; 

• The registrant will develop a case-specific resistance management action plan within 90 days 

according to the characteristics of the resistance event and local agronomic needs. The registrant 

will consult with appropriate stakeholders in the development of the action plan. and the details 

of such a plan shall be approved by EPA prior to implementation; 

• Notify affected parties (e .g. growers, consultants, extension agents, seed distributors, 

university cooperators and state/ federal authorities as appropriate) in the region of the resistance 

situation and approved action plan; and 

• In subsequent growing seasons, maintain sales suspension and alternative resistance 

management strategies in the affected region(s) for the Bt corn hybrids that are affected by the 

resistant population until an EPA-approved local resistance management plan is in place to 

mitigate the resistance. 

A report on results of resistance monitoring and investigations of damage reports must be 

submitted to the Agency annually by August 31st each year for the duration of the conditional 

registration. 

f) Refuge Assurance Program for OAM Corn 

Pioneer must implement a Blended Seed Refuge Assurance Program designed to ensure OAM 

products are formulated with the appropriate rate of refuge seeds. The program must include the 

following four elements: 

1. Trait purity check on seed lots prior to blending; 
Optimum AcreMax B.t. Corn Seed Blends Page 35 of 54 

Biopesticides Registration Action Document

2. ISO 9000 Standard Operating Procedures for the blending process; 

3. Calibration of blending equipment; and 

4. Records and data retention records for seed blend products. 

 Calibration records - Pioneer will retain documentation for a specified period of 

time on the equipment calibration including the procedure, when it was conducted 

and the results. 

 Blend proportion records (weight and kernel based) - Pioneer will retain 

documentation for a specified period of time on the kernel per pound data of the 

components, the calculations to determine the proportions based on weight and 

the actual weights that are blended together to make up an OAM product by seed 

lot. 

All records must be maintained at the Pioneer blending facility and must be available for the 

EPA review upon request. 

g) Annual Reporting Requirements for OAM Corn 

1. Annual Sales: reported and summed by state (county level data available by 

request) January 31st each year, beginning in 2012; 

2. Grower Agreements: number of units of OAM corn seed shipped or sold and 

not returned, and the number of such units that were sold to persons who have 

signed grower agreements, January 31st each year, beginning in 2012; 

3. Grower Education: substantive changes to education program completed 

previous year, January 31st each year, beginning in 2011; 

4. Compliance Assurance Program: compliance assurance program activities 

and results for the prior year and plans for the compliance assurance program 

for the current year, January 31st each year, beginning in 2012; 

5. Compliance Survey Results: results of annual surveys for the prior year and 

survey plans for the current year; full report January 31st each year, beginning 

in 2012; 

6. Insect Resistance Monitoring Results: results of monitoring and 

investigations of damage reports, August 31st each year, beginning in 2012 for 

western corn rootworm and northern corn rootworm. 

OAM XTRA; EPA Registration Number 29964-11

This product is conditionally registered in accordance with FIFRA Section 3(c)(7)(A) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended, provided that you do 

 the following terms and conditions. 

1] The subject registration will automatically expire on midnight September 1, 2011. 

2] The subject registration will be limited to a seed mix of TC1507 (Cry1F) xDAS-59122-7 

(Cry34Ab1/Cry35Ab1) x Cry1Ab corn seed blended with not less than 10% non-Bt corn seed. 

3] Submit/cite all data required for registration of your product under FIFRA § 3(c)(5) when the 

Agency requires registrants of similar products to submit such data. 
Optimum AcreMax B.t. Corn Seed Blends Page 36 of 54 

Biopesticides Registration Action Document

4] This plant-incorporated protectant may be combined through conventional breeding with other 

registered plant-incorporated protectants that are similarly approved for use in combination, 

through conventional breeding, with other registered plant-incorporated protectants to produce 

inbred corn lines and hybrid corn varieties with combined pesticidal traits. 

5] Submit or cite all data required to support 1507x MON810x59122 within the timeframes 

required by the terms and conditions of EPA Registration Number 29964-8. 

6] The following seed blend related IRM data is being required to support a longer term analysis 

of the potential for insect resistance developing from the use of two toxin based Bt corn seed 

blends targeting European corn borer and southwestern corn borer. Provided the registration 

expiration date is extended, submit an interim report on the following data within one year and a 

final report within two years. 

g) Ovipositional behavior in seed blends under, for example, increased pest pressure; 

h) The potential and degree of crowding out refuge plants by Bt protected plants in 

blends expressing corn rootworm traits under different environmental 

conditions and higher pest pressure; 

i) Adult movement (related to mating and movement from refuges), larval movement, 

larval feeding (i.e., selective feeding within corn ears or on pollen), survival of 

heterozygote genotypes on OAM (markers may need to be determined for heterozygotes), 

and the potential for epistatic mechanisms of resistance (particularly with older instars).

7] In order to improve the strength of modeling, you must incorporate the following into your 

model and clarify certain assumptions utilized within 120 days of the date of this registration: 

m) Non-uniform oviposition for both generations of lepidoptera in a 10% seed blend (OAM 

Xtra); 

n) Non-uniform oviposition for the second generation of lepidoptera in a 5% seed blend 

without a corn rootworm trait; and 

o) Increased female (SWCB) pre-ovipositional dispersal out of seed blends. 

p) How was fecundity increased in seed blends? Does the 6-fold (and 4-fold) increase refer 

to the fecundity of susceptible insects on refuge plants relative to fecundity on Bt plants? 

q) How was uniform oviposition dealt with in the model code? The methodology should be 

explained. Do adults form one big random mating pool in seed blends, and eggs are 

uniformly applied across the field (or else)? 

r) How was non-uniform oviposition dealt with in the model code of the sensitivity 

analysis? Pioneer/DuPont should explain the methodology used. 

8] Pioneer must implement the following Insect Resistance Management Program: 

The required IRM program for OAM Xtra corn must have the following elements: 

Requirements relating to creation of a lepidopteran refuge (consisting of corn that does not 

contain any Bt trait for lepidopteran control) in cotton growing regions in conjunction with the 

planting of any acreage of OAM Xtra corn; 

Requirements for Pioneer to prepare and require OAM XTRA users to sign “grower 

agreements,” that impose binding contractual obligation on the grower to comply with the refuge 
Optimum AcreMax B.t. Corn Seed Blends Page 37 of 54 

Biopesticides Registration Action Document

requirements; 

Requirements regarding programs to educate growers about IRM requirements; 

Requirements regarding programs to evaluate and promote growers’ compliance with IRM 

requirements; 

Requirements regarding programs to evaluate whether there are statistically significant and 

biologically relevant changes in target insect susceptibility to Cry1F and Cry34Ab1/Cry35Ab1 

proteins in the target insects; 

Requirements regarding a “remedial action plan,” that contains measures Pioneer would take in 

the event that any field-relevant insect resistance was detected as well as to report on activity 

under the plan to EPA; 

Annual reports on units sold by state (units sold by county level will be made available to the 

Agency upon request), IRM grower agreements results, and the compliance assurance program 

including the educational program on or before January 31st of each year, beginning in 2011. 

e) Refuge requirements for OAM XTRA 

Corn-Belt/Non-Cotton Growing Areas 

Optimum® AcreMaxTM Xtra Insect Protection contains a Lepidopteran and corn rootworm refuge 

that is “in the bag” and is automatically implemented when the grower plants the product. No 

additional refuge is required when planting this product. 

Foliar insecticide treatments for control of European corn borer, corn earworm, southwestern 

corn borer, fall armyworm, black cutworm, western bean cutworm, lesser corn stalk borer, 

southern corn stalk borer, and sugarcane borer may be applied only if economic thresholds are 

reached for one or more of these target pests. Foliar insecticide treatments are also permitted for 

control of corn rootworm adults if economic thresholds are reached. Economic thresholds will 

be determined using methods recommended by local or regional professionals (e.g., Extension 

Service agents, crop consultants). 

Cotton-Growing Region Refuge Requirements 

In cotton-growing regions where corn earworm is a significant pest: 

 The 20% refuge must be planted with non-Bt corn hybrids. 

 Optimum® AcreMaxTM Xtra and the 20% non-Bt refuge should be sown on the same day, or 

with the shortest window possible between planting dates 

 External refuges may be planted as an in-field or adjacent (e.g., across the road) refuge or as 

a separate block within 1/2 mile of the Optimum® AcreMaxTM Xtra corn field. 

 In field refuge options include: blocks, perimeter strips (i.e., along the edges or headlands), 

or in-field strips. 

 When planting the refuge in strips across the field, refuges must be at one (1) row wide. 

 Insecticide treatments for control of European corn borer, corn earworm, southwestern corn 

borer, fall armyworm, black cutworm, western bean cutworm, lesser corn stalk borer, 
Optimum AcreMax B.t. Corn Seed Blends Page 38 of 54 

Biopesticides Registration Action Document

southern corn stalk borer, and sugarcane borer may be applied only if economic thresholds 

are reached for one or more of these target pests. In addition, the refuge can be protected 

from CRW damage by an appropriate seed treatment or soil insecticide; however, 

insecticides labeled for adult CRW control must be avoided in the refuge during the period of 

CRW adult emergence. Economic thresholds will be determined using methods 

recommended by local or regional professionals (e.g., Extension Service agents, crop 

consultants). Microbial Bt insecticides must not be applied to non-Bt corn refuge plants. 

 Cotton-growing areas include the following states: Alabama, Arkansas, Georgia, Florida, 

Louisiana, North Carolina, Mississippi, South Carolina, Oklahoma (only the counties of 

Beckham, Caddo, Comanche, Custer, Greer, Harmon, Jackson, Kay, Kiowa, Tillman, 

Washita), Tennessee (only the counties of Carroll, Chester, Crockett, Dyer, Fayette, Franklin, 

Gibson, Hardeman, Hardin, Haywood, Lake, Lauderdale, Lincoln, Madison, Obion, 

Rutherford, Shelby, and Tipton), Texas (except the counties of Carson, Dallam, Hansford, 

Hartley, Hutchinson, Lipscomb, Moore, Ochiltree, Roberts, and Sherman), Virginia (only the 

counties of Dinwiddie, Franklin City, Greensville, Isle of Wight, Northampton, 

Southampton, Suffolk City, Surrey, Sussex) and Missouri (only the counties of Dunklin, New 

Madrid, Pemiscot, Scott, Stoddard). 

These refuge requirements do not apply to seed propagation of inbred and hybrid corn seed corn 

up to a total of 20,000 acres per county and up to a combined U.S. total of 250,000 acres per PIP 

active ingredient per registrant per year. 

When on-farm assessments identify non-compliance with refuge requirements for one or more Bt

corn products, additional educational material and assistance are provided by the registrant to 

help these growers meet the refuge requirements across their farming operations. 

f) Grower Agreement for OAM XTRA Corn 

8. Persons purchasing OAM XTRA corn must sign a grower agreement. The term 

“grower agreement” refers to any grower purchase contract, license agreement, or 

similar legal document. 

9. The grower agreement and/or specific stewardship documents referenced in the 

grower agreement must clearly set forth the terms of the current IRM program. 

By signing the grower agreement, a grower must be contractually bound to 

comply with the requirements of the IRM program. 

10. Pioneer must implement a system equivalent to what is already approved for 

previously registered Pioneer Bt corn products, which is reasonably likely to 

assure that persons purchasing OAM XTRA corn will affirm annually that they 

are contractually bound to comply with the requirements of the IRM program. A 

description of the system must be submitted to EPA within 90 days from the date 

of registration. (This information has been submitted and is being evaluated by 

the Agency.) 

11. Pioneer must use a grower agreement and must submit to EPA, within 90 days 

from the date of registration, a copy of that agreement and any specific 

stewardship documents referenced in the grower agreement. (This information 

has been submitted and is being evaluated by the Agency.)If Pioneer wishes to 
Optimum AcreMax B.t. Corn Seed Blends Page 39 of 54 

Biopesticides Registration Action Document

change any part of the grower agreement or any specific stewardship documents 

referenced in the grower agreement that would affect either the content of the 

IRM program or the legal enforceability of the provisions of the agreement 

relating to the IRM program, 30 days prior to implementing a proposed change, 

Pioneer must submit to EPA the text of such changes to ensure it is consistent 

with the terms and conditions of this registration. 

12. Pioneer shall maintain records of all OAM XTRA corn grower agreements for a 

period of three years from December 31st of the year in which the agreement was 

signed. 

13. Beginning on January 31, 2012, and annually thereafter, Pioneer shall provide 

EPA with a report on the number of units of OAM XTRA corn seed shipped and 

not returned, and the number of such units that were sold to persons who have 

signed grower agreements. The report shall cover the time frame of a twelvemonth period. Note: The first report shall contain the specified information from 

the time frame starting with the date of registration and extending through the 

2011 growing season. 

14. Pioneer must allow a review of the grower agreements and grower agreement 

records by EPA or by a State pesticide regulatory agency if the State agency can 

demonstrate that confidential business information, including names, personal 

information, and grower license number, will be protected. 

g) IRM Education and IRM Compliance Monitoring Program for OAM XTRA Corn 

2. Pioneer must design and implement a comprehensive, ongoing IRM education 

program designed to convey to OAM XTRA corn users the importance of 

complying with the IRM program. The program must also address unexpected 

pest damage and guidance for growers in this area. The education program shall 

involve the use of multiple media, e.g. face-to-face meetings, mailing written 

materials, EPA-reviewed language on IRM requirements on the bag or bag tag, 

and electronic communications such as by internet, radio, or television 

commercials. Copies of the materials will be provided to EPA for their records. 

The program shall involve at least one written communication annually to each 

OAM XTRA corn user separate from the grower technical guide. The 

communication shall inform the user of the current IRM requirements and 

specifically the need to plant a lepidopteran refuge in cotton growing regions. 

Pioneer shall coordinate its education program with the educational efforts of 

other registrants and other organizations, such as the National Corn Growers 

Association and state extension programs. 

2. Pioneer must design and immediately implement a “bag tag” that will be attached 

to all bags of OAM XTRA seed sold and delivered for the 2011 growing season and 

annually thereafter. The purpose of this bag tag is to remind growers that OAM 

XTRA products require a separate 20% lepidopteran refuge in cotton-growing areas. 

The PIP product label accepted by EPA must include how this information will be 

conveyed to growers via text and graphics. A revised PIP product label must be 

submitted by January 31, 2011. 
Optimum AcreMax B.t. Corn Seed Blends Page 40 of 54 

Biopesticides Registration Action Document

3. Pioneer must conduct targeted, on-farm compliance assessments for growers who 

purchase OAM XTRA seed to ensure growers are compliant with the requirement of 

a 20% refuge for lepidopteran pests in cotton growing areas. For the 2011 growing 

season and thereafter, Pioneer must conduct on-farm assessments or roughly half the 

number of assessments that Pioneer will contribute to the 2011 Agricultural 

Biotechnology Stewardship Technical Committee (ABSTC) compliance assurance 

program assessment for corn borer and stacked products. Pioneer must contract with 

an independent third party to conduct these compliance assessments. The table below 

reflects the relative number of on-farm assessments for OAM XTRA based on 

Pioneer’s contribution to the ABSTC compliance assurance program report and is 

subject to change with time as appropriate. 

i. A third party is classified as a party other than the registrant, the grower, or anyone 

else with a direct interest in IRM compliance for Bt corn. 

Pioneer must provide a report to EPA summarizing the OAM XTRA compliance 

assurance program activities and results for the prior year and plans for the OAM XTRA 

compliance assurance program for the current year, by January 31, 2012, and annually 

thereafter. Within one month of submitting this report to EPA, the registrant shall meet 

with EPA to discuss its findings. The report must inform EPA of the number of growers 

deemed ineligible to purchase Bt corn seed on the basis of continued non-compliance 

with the insect resistance management refuge requirements. 

4. Annually, Pioneer shall revise, and expand as necessary, its education program to take 

into account the information collected through the compliance survey and from other 

sources. The changes shall address aspects of grower compliance that are not sufficiently 

high. 

5. Beginning January 31, 2012, Pioneer must provide a report to EPA summarizing the 

activities it carried out under its education program for the prior year. Annually 

thereafter, Pioneer must provide EPA any substantive changes to its grower education 

activities as part of the overall IRM compliance assurance program report. Pioneer must 

either submit a separate report or contribute to the report from the industry working 

group, ABSTC. 

6. The registrant shall revise and expand its existing Compliance Assurance Program to 

include the following elements. The registrant must prepare and submit by January 31, 

2012, a written description of its revised Compliance Assurance Program. The registrant 

may coordinate with other registrants in designing and implementing its Compliance 

Assurance Program. 

7. The registrant will enhance the refuge education program throughout the seed delivery 

channel: 

i. Ensure sales representatives, licensees, seed dealers, and growers recognize the 

importance of correct refuge implementation and potential consequences of failure to 

plant the required refuge; 
Optimum AcreMax B.t. Corn Seed Blends Page 41 of 54 

Biopesticides Registration Action Document

ii. Pioneer must design and immediately implement a “bag tag” that will be attached to all 

bags of OAM XTRA seed sold and delivered for the 2011 growing season and annually 

thereafter. The purpose of this bag tag is to remind growers that OAM XTRA products 

require a separate 20% lepidopteran refuge in cotton growing areas. The PIP product 

label accepted by EPA must include how this information will be conveyed to growers 

via text and graphics. A revised PIP product label must be submitted by January 31, 

2011. 

8. The registrant will focus the majority of on-farm assessments on regions with the 

greatest risks for resistance: 

i. Use Bt corn adoption, pest pressure information, and other available information to 

identify regions where the risk of resistance is greatest; 

ii. Focus approximately two-thirds of on-farm assessments on these regions, with the 

remaining assessments conducted across other regions where the product is used. 

9. The registrant will use its available Bt sales records and other information to refine 

grower lists for on-farm assessments of their compliance with refuge requirement: 

i. Identify for potential on-farm assessment growers whose sales information indicates 

they have purchased the Bt corn product but may have purchased little or no refuge seed 

from the registrant, licensee, or affiliated company. 

10. The registrant will contract with third parties to perform on-farm assessments of 

compliance with refuge requirements: 

i. The third-party assessors will conduct all first-time on-farm assessments as well as 

second-year on-farm assessments of those growers found out of compliance in a firsttime assessment 

11. The registrant will annually refine the on-farm assessment program for the Bt corn 

product to reflect the adoption rate and level of refuge compliance for the product. 

12. The registrant will follow up with growers who have been found significantly out of 

compliance under the on-farm assessment program and are found to be back in 

compliance the following year: 

i. All growers found to be significantly out of compliance in a prior year will annually be 

sent additional refuge assistance information for a minimum of two years by the 

registrant, seed supplier, or third party assessor, after completing the assessment process; 

ii. The registrant will conduct follow-up checks on growers found to be significantly out 

of compliance within three years after they are found to be back in compliance; 

iii. A grower found with a second incident of significant non-compliance with refuge 

requirements for the Bt corn product within a five-year period will be denied access to 
Optimum AcreMax B.t. Corn Seed Blends Page 42 of 54 

Biopesticides Registration Action Document

Pioneer Hi-Bred’s Bt corn products the next year. Similarly, seed dealers who are not 

fulfilling their obligations to inform/educate growers of their IRM obligations will lose their 

opportunity to sell Bt corn. 

h) Insect Resistance Monitoring and Remedial Action Plan for OAM XTRA Corn 

The Agency is imposing the following conditions for this lepidopteran toxin: 

The registrant will monitor for resistance to its lepidopteran-resistant Bt corn. The monitoring 

program shall consist of two approaches: (1) focused population sampling and laboratory testing; 

and (2) investigation of reports of less-than expected control of labeled insects. Should fieldrelevant resistance be confirmed, an appropriate resistance management action plan will be 

implemented. 

(2) Focused Population Sampling 

The registrant shall annually sample and bioassay populations of the key target pests Ostrinia 

nubilalis (European corn borer; ECB), Diatraea grandiosella (Southwestern corn borer; S 

WCB), and Helicoverpa zea (corn earworm; CEW). Sampling for the target pests will be focused 

in areas identified as those with the highest risk of resistance development (e.g., where 

lepidopteran-active Bt hybrids are planted on a high proportion of the corn acres, and where the 

insect species are regarded as key pests of corn). Bioassay methods must be appropriate for the 

goal of detecting field-relevant shifts in population response to lepidopteran resistant Bt corn 

and/or changes in resistance allele frequency in response to the use of Bt corn and, as far as 

possible, should be consistent across sampling years to enable comparisons with historical data. 

The number of populations to be collected shall reflect the regional importance of the insect 

species as a pest, and specific collection regions will be identified for each pest. For ECB, a 

minimum of 12 populations across the sampling region will be targeted for collection at each 

annual sampling. For SWCB, the target will be a minimum of six populations. For CEW, the 

target will be a minimum of 10 populations. Pest populations should be collected from multiple 

corn-growing states reflective of different geographies and agronomic conditions. To obtain 

sufficient sensitivity to detect resistance alleles before they become common enough to cause 

measurable field damage, each population collection shall attempt to target 400 insect genomes 

(egg masses, larvae, mated females, and/or mixed-sex adults), but a successful population 

collection will contain a minimum of 100 genomes. It is recognized that it may not be possible to 

collect the target number of insect populations or genomes due to factors such as natural 

fluctuations in pest density, environmental conditions, and area-wide pest suppression. 

The sampling program and geographic range of collections may be modified as appropriate 

based on changes in pest importance and for the adoption levels of lepidopteran-resistant Bt corn. 

The Agency shall be consulted prior to the implementation of such modifications. 

The registrant will report to the Agency before August 31 each year the results of the population 

sampling and bioassay monitoring program. 

Any incidence of unusually low sensitivity to the Bt protein in bioassays shall be investigated as 

soon as possible to understand any field relevance of such a finding. Such investigations shall 
Optimum AcreMax B.t. Corn Seed Blends Page 43 of 54 

Biopesticides Registration Action Document

proceed in a stepwise manner until the field relevance can be either confirmed or refuted, and 

results of these shall be reported to the Agency annually before August 31. The investigative 

steps will include: 

1. Re-test progeny of the collected population to determine whether the unusual bioassay 

response is reproducible and heritable. If it is not reproducible and heritable, no further action is 

required. 

2. If the unusual response is reproducible and heritable, progeny of insects that survive the 

diagnostic concentration will be tested using methods that are representative of exposure to Bt

corn hybrids under field conditions. If progeny do not survive to adulthood, any suspected 

resistance is not field relevant and no further action is required. 

3. If insects survive steps 1 and 2, resistance is confirmed, and further steps will be taken to 

evaluate the resistance. These steps may include: 

 determining the nature of the resistance (i.e., recessive or dominant, and the level 

of functional dominance); 

 estimating the resistance-allele frequency in the original population; 

 determining whether the resistance-allele Frequency is increasing by analyzing field 

collections in subsequent years sampled from the same site where the resistance allele(s) 

was originally collected; 

 determining the geographic distribution of the resistance allele by analyzing field 

collections in subsequent years from sites surrounding the site where the resistance 

allele(s) was originally collected. 

Should field-relevant resistance be confirmed, and the resistance appears to be increasing or 

spreading, the registrant will consult with the Agency to develop and implement a case-specific 

resistance management action plan. 

(2) Investigation of Reports of Unexpected Levels of Damage by the Target 

Pests: 

The registrant will follow up on grower, extension specialist or consultant reports of unexpected 

levels of damage by the lepidopteran pests listed on the pesticide label. The registrant will 

instruct its customers to contact them if such incidents occur. The registrant will investigate all 

legitimate reports submitted to the company or the company's representatives. 

If reports of unexpected levels of damage lead to the suspicion of resistance in any of the key 

target pests (ECB, SWCB, and CEW), the registrant will implement the actions described below, 

based on the following definitions of suspected resistance and confirmed resistance. 

Suspected resistance

EPA defines suspected resistance to mean field reports of unexpected levels of insect feeding 

damage for which: 
Optimum AcreMax B.t. Corn Seed Blends Page 44 of 54 

Biopesticides Registration Action Document

 the corn in question has been confirmed to be lepidopteran-active Bt corn; 

 the seed used had the proper percentage of corn expressing Bt protein; 

 the relevant plant tissues are expressing the expected level of Bt protein; and 

 it has been ruled out that species not susceptible to the protein could be responsible for 

the damage, that no climatic or cultural reasons could be responsible for the damage, and 

that that there could be no other reasonable causes for the damage. 

The Agency does not interpret suspected resistance to mean grower reports of possible control 

failures or suspicious results from annual insect monitoring assays, nor does the Agency intend 

that extensive field studies and testing be undertaken to confirm scientifically the presence of 

insects resistant to Bt corn in commercial production fields before responsive measures are 

undertaken. 

If resistance is suspected, the registrant will instruct growers to do the following: 

 Use alternative control measures in the Bt corn fields in the affected region to control the 

target pest during the immediate growing season. 

 Destroy Bt corn crop residues in the affected region within one month after harvest with a 

technique appropriate for local production practices to minimize the possibility of 

resistant insects over-wintering and contributing to the next season's target pest 

population. 

Additionally, if possible, and prior to the application of alternative control measures or 

destruction of crop residue, the registrant will collect samples of the insect population in the 

affected fields for laboratory rearing and testing. Such rearing and testing shall be conducted as 

expeditiously as practical. 

Confirmed resistance 

EPA defines confirmed resistance to mean, in the case of field reports of unexpected levels of 

damage from the key target pests, that all the following criteria are met: 

 There is >30% insect survival and commensurate insect feeding in a bioassay, initiated 

with neonate larvae, that uses methods that are representative of exposure to Bt corn 

hybrids under field conditions (ECB and SWCB only). 

 In standardized laboratory bioassays using diagnostic concentrations of the Bt protein 

suited to the target pest in question, the pest exhibits resistance that has a genetic basis 

and the level of survivorship indicates that there may be a resistance allele frequency of ≥

0.1 in the sampled population. 

 In standardized laboratory bioassays, the LC50 exceeds the upper limit of the 95% 

confidence interval of the LC50 for susceptible populations surveyed both in the original 

baselines developed for this pest species and in previous years of field monitoring. 
Optimum AcreMax B.t. Corn Seed Blends Page 45 of 54 

Biopesticides Registration Action Document

(3) Response to Confirmed Resistance in a Key Target Pest as the Cause of Unexpected 

Levels of Damage in the Field 

When field resistance is confirmed (as defined above), the following steps will be taken by the 

registrant: 

 EPA will receive notification within 30 days of resistance confirmation; 

 Affected customers and extension agents will be notified about confirmed resistance 

within 30 days; 

 Monitoring will be increased in the affected area and local target pest populations will be 

sampled annually to determine the extent and impact of resistance; 

 If appropriate (depending on the resistant pest species, the extent of resistance, the timing 

of resistance, and the nature of resistance, and the availability of suitable alternative 

control measures), alternative control measures will be employed to reduce or control 

target pest populations in the affected area. Alternative control measures may include 

advising customers and extension agents in the affected area to incorporate crop residues 

into the soil following harvest to minimize the possibility of over-wintering insects, 

and/or applications of chemical insecticides; 

 Unless otherwise agreed with EPA, stop sale and distribution of the relevant 

lepidopteran-active Bt corn hybrids in the affected area immediately until an effective 

local mitigation plan approved by EPA has been implemented; 

 The registrant will develop a case-specific resistance management action plan within 90 

days according to the characteristics of the resistance event and local agronomic needs. 

The registrant will consult with appropriate stakeholders in the development of the action 

plan, and the details of such a plan shall be approved by EPA prior to implementation; 

 Notify affected parties (e.g. growers, consultants, extension agents, seed distributors, 

university cooperators and state/federal authorities as appropriate) in the region of the 

resistance situation and approved action plan; and 

 In subsequent growing seasons, maintain sales suspension and alternative resistance 

management strategies in the affected region(s) for the Bt corn hybrids that are affected 

by the resistant population until an EPA-approved local resistance management plan is in 

place to mitigate the resistance. 

A report on results of resistance monitoring and investigations of damage reports must be 

submitted to the Agency annually by August 31st each year for the duration of the conditional 

registration. 

The Agency is imposing the following conditions for this corn rootworm toxin: 

In addition to the existing two-pronged approach to insect resistance monitoring (monitoring 

insect populations using the diet bioassay and investigations of field reports) that are required for 

Cry34/35 for Herculex Rootworm Insect Protection (29964-4) and Herculex Xtra Insect 

Protection (29964-5), Pioneer must also conduct enhanced monitoring using the Sublethal 
Optimum AcreMax B.t. Corn Seed Blends Page 46 of 54 

Biopesticides Registration Action Document

Seedling Assay as a complement to the diet bioassay method. Pioneer must submit a detailed 

OAM XTRA/OAMRW-specific resistance monitoring plan to the Agency by December 1, 2010. 

With respect to the implementation of the Sublethal Seedling Assay: 

1. Pioneer must monitor for resistance and or changes in target pest susceptibility that will 

lead to increased injury potential in western and northern corn rootworm feeding on the 

rootworm component of OAM XTRA products. Sampling must be focused in the four 

regions of highest risk of resistance development: Region – 1 (Illinois, Indiana); Region 

2 (Iowa, Missouri), Region 3 (Nebraska and Kansas), and Region 4 (Minnesota, South 

Dakota and Wisconsin). 

2. Pioneer must provide the EPA its detailed western corn rootworm resistance monitoring 

plan for approval by December 1, 2010, and its northern corn rootworm resistance 

monitoring plan for approval by December 1, 2011. These plans will include baseline 

(benchmark) susceptibility data and an enhanced annual resistance monitoring plan. The 

reports will contain: 

 Sampling scheme: annual collection should target a range of 16-20 western 

and/or northern rootworm populations (4-5 per region), with a minimum 

number of 2,000 beetles collected per population. 

 Bioassay methodology (precision, detection level, etc.). Pioneer must 

bioassay a target of 3000 larvae on 59122 plants for each population. 

 A description of how monitoring results relate to and are predictive of changes 

in field efficacy, and change in injury potential to DAS-59122-7 constituting 

product failure and development of a remedial action plan. 

3. Pioneer will provide the EPA with an annual OAM XTRA resistance monitoring report 

by August 31st of each year beginning with 2011 for western corn rootworm and 2012 for 

northern corn rootworm, reporting on populations collected the previous year. 

In addition to screening of wide-area corn rootworm populations as outlined above, for 

the second prong of resistance monitoring Pioneer must investigate grower, extension 

specialist or consultant reports of less-than-expected efficacy or field performance of 

OAM XTRA products. 

i) Remedial Action Plan for Corn Rootworm and OAM XTRA Corn 

The remedial action plan is designed as a tiered approach for mitigating western and northern 

corn rootworm resistance development specifically due to the commercialization of OAM XTRA 

corn. The following program summary describes, in order of events, the steps that must be taken 

to implement a remedial action plan if resistance to target pests is confirmed. 

Pioneer will complete a benchmark study of susceptibility of western corn rootworm using the 

Sublethal Seedling Assay and analyze field efficacy data to set a benchmark for expected levels 

of damage to finalize the OAM XTRA remedial action plan by December 1, 2010, so that 

decision points regarding crop damage and target pest resistance are established, and a remedial 

action plan can be initiated when needed. Although northern corn rootworm is difficult to rear in 

the laboratory, Pioneer will attempt to complete a benchmark study for susceptibility of northern 

corn rootworm using the Sublethal Seedling Assay. 
Optimum AcreMax B.t. Corn Seed Blends Page 47 of 54 

Biopesticides Registration Action Document

1. Suspected Resistance from Population Monitoring 

Definition of Suspected Resistance - Resistance will be suspected if investigations of target pest 

injury potential to OAM XTRA maize from the Sublethal Seedling Assay show that: 

 Injury potential of a target pest population obtained as part of the annual insect 

monitoring program has increased to a level representative of product failure in 

field conditions; 

 The seeds used in the investigation of this population’s injury potential contain 

Cry34/Cry35Ab1 at levels representative of (and in the same genetic background 

as) the benchmark study; and 

 The change in injury potential has been documented as a heritable characteristic 

of the target pest population and not a result of experimental error. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment and/or crop rotation or use of soil or seedapplied insecticides at rates providing corn rootworm control the following year. These 

measures are intended to educate growers of the potential for change in efficacy, reduce the 

possibility of grower loss from change in efficacy and reduce potentially resistant insects 

contributing to the following year's pest population. 

2. Confirmed Resistance from Population Monitoring 

Definition of Confirmed Resistance - Resistance will be confirmed if all of the following criteria 

are met by progeny from a subsequent rootworm population collected from the area of 

"suspected resistance" the following year: 

 Injury potential of the subsequent field-collected rootworm population feeding on 

plants containing DAS-59122-7 remains at a level likely to produce repeated 

product failure in field conditions; 

 The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

 Greenhouse node-injury evaluation confirms product failure; 

 Subsequent populations collected from the area and assayed show that the results 

are repeatable; and 

 Continued monitoring of the area suggests that the change is spreading. 

3. Suspected Resistance – Investigation of Field Reports 

The registrant will follow up on grower, extension specialist or consultant reports of unexpected 

product performance due to corn rootworm species listed on the label. The registrants will 

instruct its customers to contact them if such incidents occur. The registrants will investigate all 

such reports submitted to the company or the company’s representatives. 

 Confirm the corn in question is rootworm-active Bt corn; 

 Confirm the field in question contains the correct blend rate of refuge corn; 

 Confirm that species not susceptible to the protein are not responsible for the 
Optimum AcreMax B.t. Corn Seed Blends Page 48 of 54 

Biopesticides Registration Action Document

damage, that no climatic or cultural reasons could be responsible for the 

damage, and that all other reasonable causes based on historical experience for 

the observed root damage have been ruled out; 

 If not due to other reasons, the registrant will conduct a thorough investigation 

of the factors known to affect the manifestation of corn rootworm feeding 

damage. 

 If the investigation fails to rule out target pest resistance as the cause, 

resistance is suspected. 

If resistance is "suspected", Pioneer will inform growers in the area of the potential benefit of 

augmenting CRW control such as adulticide treatment, crop rotation the following year or use of 

soil or seed insecticides the following year. These measures are intended to educate growers of 

the potential for change in efficacy, reduce the possibility of grower loss from change in efficacy 

and reduce potentially resistant insects contributing to the following year's pest population. 

Pioneer will collect insects as soon as possible from the area for laboratory studies to test for 

resistance by comparing with benchmark susceptibility data. These studies will be performed 

following the same laboratory protocols as used for the benchmark determination and monitoring 

programs. 

4. Confirmed Resistance – Investigation of Field Reports 

 Injury potential of the field-collected rootworm population feeding on plants 

containing DAS-59122-7 remains at a level likely to produce repeated product 

failure in field conditions; 

 Subsequent populations collected from the area and assayed show that the results 

are repeatable; 

 The change in injury potential has been documented as a heritable characteristic 

of the target pest population; 

 Greenhouse node-injury evaluation confirms product failure; and

 Continued monitoring of the area suggests that the change is spreading.

5. Remedial Action 

When resistance is "confirmed", the following steps will be taken: 

 The EPA will receive notification within 30 days of confirmed resistance; 

 Affected customers and Extension specialists will be immediately notified about 

confirmed resistance; 

 Affected customers and Extension specialists will be strongly encouraged to 

implement alternative CRW control measures such as adulticide treatment, crop 

rotation the following year, or use of soil or seed insecticides the following year; 

 Within 60 days of notification, Pioneer and EPA will jointly determine the extent 

of the mitigation needed and determine whether sales should be stopped on an 

appropriate geographic (i.e., county or regional) basis; and 

 Pioneer will develop a case-specific resistance mitigation action plan within 90 

days according to the characteristics of the resistance event and local agronomic 
Optimum AcreMax B.t. Corn Seed Blends Page 49 of 54 

Biopesticides Registration Action Document

needs. Pioneer will consult with appropriate stakeholders in the development of 

the action plan, and the details of such a plan shall be approved by the EPA prior 

to implementation. The resistance management plan could include such measures 

layering additional technologies in future OAM XTRA products. 

f) Remedial Action Plan for lepidopteran pests and OAM XTRA Corn 

When field resistance is confirmed (as previously defined), the following steps will be taken by 

the registrant: 

• EPA will receive notification within 30 days of resistance confirmation; 

• Affected customers and extension agents will be notified about confirmed resistance 

within 30 days; 

• Monitoring will be increased in the affected area and local target pest populations will be 

sampled annually to determine the extent and impact of resistance; 

• If appropriate (depending on the resistant pest species, the extent of resistance, the timing of 

resistance, and the nature of resistance, and the availability of suitable alternative control 

measures) , alternative control measures will be employed to reduce or control target pest 

populations in the affected area. Alternative control measures may include advising customers 

and extension agents in the affected area to incorporate crop residues into the soil following 

harvest to minimize the possibility of over-wintering insects, and/or applications of chemical 

insecticides; 

• Unless otherwise agreed with EPA, stop sale and distribution of the relevant lepidopteranactive Bt corn hybrids in the affected area immediately until an effective local mitigation plan 

approved by EPA has been implemented; 

• The registrant will develop a case-specific resistance management action plan within 90 days 

according to the characteristics of the resistance event and local agronomic needs. The registrant 

will consult with appropriate stakeholders in the development of the action plan. and the details 

of such a plan shall be approved by EPA prior to implementation; 

• Notify affected parties (e .g. growers, consultants, extension agents, seed distributors, 

university cooperators and state/ federal authorities as appropriate) in the region of the resistance 

situation and approved action plan; and 

• In subsequent growing seasons, maintain sales suspension and alternative resistance 

management strategies in the affected region(s) for the Bt corn hybrids that are affected by the 

resistant population until an EPA-approved local resistance management plan is in place to 

mitigate the resistance. 

A report on results of resistance monitoring and investigations of damage reports must be 

submitted to the Agency annually by August 31st each year for the duration of the conditional 

registration. 

g) Refuge Assurance Program for OAM XTRA Corn 
Optimum AcreMax B.t. Corn Seed Blends Page 50 of 54 

Biopesticides Registration Action Document

Pioneer must implement a Blended Seed Refuge Assurance Program designed to ensure OAM 

XTRA products are formulated with the appropriate rate of refuge seeds. The program must 

include the following four elements: 

5. Trait purity check on seed lots prior to blending; 

6. ISO 9000 Standard Operating Procedures for the blending process; 

7. Calibration of blending equipment; and 

8. Records and data retention records for seed blend products. 

 Calibration records - Pioneer will retain documentation for a specified period of 

time on the equipment calibration including the procedure, when it was conducted 

and the results. 

 Blend proportion records (weight and kernel based) - Pioneer will retain 

documentation for a specified period of time on the kernel per pound data of the 

components, the calculations to determine the proportions based on weight and 

the actual weights that are blended together to make up an OAM XTRA product 

by seed lot. 

All records must be maintained at the Pioneer blending facility and must be available for the 

EPA review upon request. 

h) Annual Reporting Requirements for OAM XTRA Corn 

7. Annual Sales: reported and summed by state (county level data available by 

request) January 31st each year, beginning in 2012; 

8. Grower Agreements: number of units of OAM XTRA corn seed shipped or 

sold and not returned, and the number of such units that were sold to persons 

who have signed grower agreements, January 31st each year, beginning in 

2012; 

9. Grower Education: substantive changes to education program completed 

previous year, January 31st each year, beginning in 2011; 

10. Compliance Assurance Program: compliance assurance program activities 

and results for the prior year and plans for the compliance assurance program 

for the current year, January 31st each year, beginning in 2012; 

11. Compliance Survey Results: results of annual surveys for the prior year and 

survey plans for the current year; full report January 31st each year, beginning 

in 2012; 

12. Insect Resistance Monitoring Results: results of monitoring and 

investigations of damage reports, August 31st each year, beginning in 2012 for 

western corn rootworm and northern corn rootworm. 

VI. REFERENCES 

Bailey, L., R. Binning, L. Higgins, D. Langer, R. Layton, S. Lefko, T. Nowatzki, E. Owens, 

and T. Rood. 2008. Trait Durability Plan for Optimum® AcreMaxTM1 Insect Protection 

Following Commercialization. Unpublished report submitted to the US EPA (MRID 473567-

09). 

BPPD, 2011a. EPA Review of Pioneer’s new product registration request, Optimum AcreMax 
Optimum AcreMax B.t. Corn Seed Blends Page 51 of 54 

Biopesticides Registration Action Document

Insect Protection, expressing Cry1F and Cry1Ab in a 5% seed blend to control lepidopteran pests 

of corn. Memo from JC Martinez to M. Mendelsohn dated May 18, 2011. 

BPPD, 2011b. Agency deficiency letter sent by Dr. Sheryl Reilly in June, 2011 addressed to 

Tracy Rood from Pioneer/DuPont. 

BPPD, 2010a. Science Assessment of Pioneer’s modeling addenda in support of their application 

of registration for Optimum AcreMax1 Insect Protection. Memo from JC Martinez to M. 

Mendelsohn dated February 4, 2010. 

BPPD, 2010b. Science risk assessment to evaluate the durability of a 10% Cry34/35 seed blend 

refuge deployment of Cry34/35 corn relative to the durability predicted for a 20% block in 

regards to Pioneer/DuPont’s Optimum AcreMax1. Memo from JC Martinez to M. Mendelsohn 

dated April 22, 2010. 

Caprio, MA, T Nowatzki, B Siegfried, LJ Meinke, RJ Wright & LD Chandler. 2006. Assessing the 

Risk of Resistance to Aerial Applications of Methyl-Parathion in the Western Corn Rootworm. 

Journal of Economic Entomology, Vol. 99(2): 483-493 

Caprio, M. A., D. Sumerford & S. Sims. 2006b. Evaluating transgenic plants for suitability in 

pest and resistance management programs, 2nd edition. L. Lacey & H. Kaya [eds]. Field 

Manual of Techniques for the Application and Evaluation of Entomopathogens. 

Coats SA, JA Mutchmor, and JJ Tollefson. 1986. Study of migratory flight in the western corn 

rootworm (Coleoptera: Chrysomeldiae). Environmental Entomology, Vol. 15: 620-625 

Davis, P. and S. MacIntosh. 2008. Benefits Document of Optimum® AcreMaxTM 1 Insect 

Protection. Unpublished report submitted by Pioneer Hi-Breed International, Inc. to the US 

EPA (MRID 473567-10). 

EPA MRID No. 47339601 Bailey, L. (2008) 2007 Insect Resistance Management Compliance 

Assurance Program Report for Corn Borer-Protected B.t. corn, Corn Rootworm-Protected B.t. 

corn, and Corn Borer/ Corn Rootworm-Protected Stacked B.t. corn. Project Number: CAP/2007. 

 Unpublished study prepared by Agricultural Biotechnology Stewardship Technical Committee. 

17 p. 

EPA MRID No.47356701 Lefko, S.; Binning, R. (2008) Characterization of Instar-Specific 

Response and Larval Recovery of Western Corn Rootworm Exposed to 59122 Maize. Project 

Number: PHI/2005/053.Unpublished study prepared by Pioneer Hi-Bred International, Inc. 

34 p. 

EPA MRID No.47356702 Lefko, S.; Binning, R. (2008) Effect of Off-Type Seeds on the 

Precision of Sublethal Corn Rootworm Seedling Assay Results. Project Number: PHI/2006/042. 

 Unpublished study prepared by Pioneer Hi-Bred International, Inc. 13 p. 

EPA MRID No.47356703 Lefko, S.; Diehn, S. (2008) An Observational Study Characterizing 

the Relative Quantity and Distribution of Cry34Ab1 and Cry35Ab1 Insecticidal Proteins in 

Roots of Maize Containing Event DAS-59122-7. Project Number: PHI/2006/119. Unpublished 

study 
Optimum AcreMax B.t. Corn Seed Blends Page 52 of 54 

Biopesticides Registration Action Document

prepared by Pioneer Hi-Bred International, Inc. 22 p. 

EPA MRID No.47356704 Lefko, S.; Binning, R. (2008) Quantifying the Concentration of 

Cry34Ab1 and Cry35Ab1 in 59122 Maize Grown in the Sublethal Corn Rootworm Seedling 

Assay System. Project Number: PHI/2006/171. Unpublished study prepared by Pioneer HiBred 

International, Inc. 11 p. 

EPA MRID No.47356705 Nowatzki, T. ; Thompson, S.; Peters, M. (2008) Field Measures of 

Adult Corn Rootworm (Coleoptera: Chrysomelidae) Production When Refuge is Deployed as a 

Seed Blend with DAS-59122-7 Maize. Project Number: PHI/2007/075. Unpublished study 

prepared by Pioneer Hi-Bred International, Inc. 57 p. 

EPA MRID No.47356706 Nowatzki, T.; Meinke, L. (2008) Impact of Western and Northern 

Corn Rootworm Larval Exposure to DAS-59122-7 in a Block Planting and a Seed Blend on Life 

History Traits of Adults. Project Number: PHI/2007/076. Unpublished study prepared by 

Pioneer 

Hi-Bred International, Inc. and University of Nebraska-Lincoln. 31 p. 

EPA MRID No.47356707 Lefko, S.; Binning, R. (2008) Investigating the Effect of Insecticidal 

Proteins Cry34/35Ab1 on Western Corn Rootworm Host Searching Behavior. Project Number: 

PHI/2007/126. Unpublished study prepared by Pioneer Hi-Bred International, Inc. 17 p. 

EPA MRID No.47356710 Davis, P.; MacIntosh, S. (2008) Benefits Document for Optimum 

AcreMax 1 Insect Protection. Project Number: PHI/2007/145. Unpublished study prepared by 

Pioneer Hi-Bred International, Inc. 21 p. 

EPA MRID No.47663301 Bailey, L. (2009) 2008 Insect Resistance Management Compliance 

Assurance Program Report for Corn Borer-Protected B.t. Corn, Corn Rootworm-Protected B.t. 

Corn, and Corn Borer/Corn Rootworm-Protected Stacked B.t. Corn. Project Number: 

CAP/2008. Unpublished study prepared by Agricultural Biotechnology Stewardship Techn. 

Committee. 15 p. 

EPA MRID No.47683801 Binning, R.; Langer, D. (2009) Additional Responses for "Pioneer's 

Benefit Documentation in Support of a Sec(3) Product Registration for Optimum AcreMax 1 

Insect Protection, also Known as Stack Herculex XTRA (Cry34/35Ab1 + Cry1F) with Herculex 

I (Cry1F, Refuge Seed for CRW) [MRID 473567-10 and Supplemental Data]": Final Report. 

Project Number: PHI/2009/026. Unpublished study prepared by Pioneer Hi-Bred International, 

Inc. 11 p. 

EPA MRID No. 48076501 Dreyer, C.; Gutsche, A.; Hubbard, N.; et al. (2010) Addendum to 

MRID 47795101 Addendum to the Benefits of Optimum AcreMax 1. Project Number: 

PHI/2009/099. Unpublished study prepared by Pioneer Hi-Bred International Inc. 33 p. 

EPA MRID No.47871001 Pan, Z.; Onstad, D.; Stanley, B.; et al. (2009) A Spatially Explicit 

Computer Simulation Study of Corn Rootworm, Diabrotica spp. [Coleoptera: Chrysomelidae]: 

Addendum. Project Number: PHI/2009/125. Unpublished study prepared by Pioneer Hi-Bred 

International, Inc. 32 p. 
Optimum AcreMax B.t. Corn Seed Blends Page 53 of 54 

Biopesticides Registration Action Document

EPA MRID No.47887901 Rood, T.; Pan, Z.; Onstad, D.; et al. (2009) Additional Addendum 

to MRID 473567-08: A Spatially Explicit Computer Simulation Study of Corn Rootworm, 

Diabrotica spp. [Coleoptera: Chrysomelidae]: Final Report. Project Number: PHI/2009/197, 

PHI/2009/125. Unpublished study prepared by Pioneer Hi-Bred International, Inc. 32 p. 

EPA MRID No.47910801 Pan, Z.; Onstad, D.; Stanley, B.; et al. (2009) Third Addendum to: 

A Spatially Explicit Computer Simulation Study of Corn Rootworm: Strip vs. Blended Refuge: 

Final Report. Project Number: PHI/2009/204, 473567/08. Unpublished study prepared by 

Pioneer Hi-Bred International, Inc. 19 p. 

EPA Scientific Advisory Panel. 2009. Transmittal of meeting minutes of the FIFRA Scientific 

Advisory Panel meeting held February 23-24, 2009 on the evaluation of the resistance risks from 

using a seed mix refuge with Pioneer’s Optimum AcreMax1 corn rootworm-protected corn. 

Memorandum from J.E. Bailey (DFO) to Dr. D. Edwards (Director of OPP) on May 6, 2009. 

EPA Scientific Advisory Panel. 2011. Transmittal Meeting Minutes of the FIFRA Scientific 

Advisory Panel Meeting Held December 8-9, 2010 to Address Scientific Issues Associated with 

Insect Resistance Management for SmartStaxTM Refuge-in-the-Bag, a Plant-Incorporated 

Protectant (PIP) Corn Seed Blend. Memorandum from Dr. Sharlene Matten (DFO) to Dr. Steven 

Bradbury (Director of OPP) on March 3, 2011. 

Grant RH and KP Seevers. 1989. Local and long-range movement of adult western corn 

rootworm (Coleoptera: Chrysomelidae) as evidenced by washup along southern lake Michigan 

shores. Envir. Entomology, Vol. 18 (2): 266-272 

Hibbard B, personal communication with Mike Caprio, January 2010 

Ives AR, PR Glaum, NL Ziebarth, and DA Andow. 2011. The evolution of resistance to twotoxin pyramid transgenic crops. Ecological Applications, Vol. 21(2): 503-515 

Jaffe, G. 2009. Complacency on the Farm. CSPI. 

Meinke LJ, personal communication with Mike Caprio, January 2010 

Meinke LJ, TW Sappington, DW Onstad, T Gullemaud, NJ Miller, J Komaromi, N Levay, L 

Furian, J Kiss, and F Toth. 2009. Western corn rootworm (Diabrotica virgifera virgifera 

LeConte) population dynamics. Agricultural and Forest Entomology, Vol.11: 29-46 

Naranjo SE. 1990. Comparative flight behavior of Diabrotica virgifera virgifera and Diabrotica 

barberi in the laboratory. Ent. Experimantalis et Aplicata, Vol. 87: 383-394 

National Academy of Science. 2010. The Impact of Genetically Engineered Crops on Farm 

Sustainability in the United States, The National Academies Press. 

Nowatzki TJ, N Bradley, KK Warren, S Putnam, LJ Meinke, DC Gosselin, FE Harvey, TE Hunt, 

and B Siegfried. 2003. In-field labeling of western corn rootworm adults (Coleoptera: 

Chrysomelidae) with Rubidium. Journal of Economic Entomology, Vol. 96(6): 1750-1759 
Optimum AcreMax B.t. Corn Seed Blends Page 54 of 54 

Biopesticides Registration Action Document

Ostlie K. 2009. Lodging in corn: diagnosis, harvesting tips, and unexpected damage in triplestack corn. http://blog.lib.umn.edu/efans/cropnews/2009/11/lodging-in-corn-diagnosis-harv.html

Ostlie K and Gassman A. 2010. BPPD teleconference with Dr. Kenneth Ostlie (University of 

Minnesota) and Dr. Aaron Gassman (Iowa State University). February 4, 2010. 

Pan Z, K Tran, H Zeng, and others (2011). Responses to EPA’s letter dated June 7, 2011 

regarding Pioneer’s Lepidopteran blended refuge products. Unpublished study submitted to the 

Agency by Pioneer Hi-Bred International, Inc. (MRID 485219-01). 

Rood, T.A. 2010. Letter to Michael Mendelsohn providing information concerning OAM 1 and 

OAM RW. 

Scott IA, JL Spencer, TR Mabry, and E Levine. 2004. Influence of atmospheric conditions on 

high-elevation flight of Western corn rootworm (Choleoptera: Chrysomelidae). 

Environmental Entomology, Vol. 33(3):650-656 

Spencer J. 2009. Personal communication. E-mail response and summary of unpublished data 

submitted to J.C. Martinez (EPA), dated December 28, 2009. 

Van Woerkom GJ, FT Turpin, & JR Barret Jr. 1983. Wind effect on western corn rootworm 

(Coleoptera: Chrysomelidae) flight behavior. Environmental Entomololgy, Vol 12: 196-200 

Vose, 2000. Risk Analysis: A quantitative guide. Wiley, New York. 

Witkowski JF, JC Owens, and JJ Tollefson. 1975. Diel activity and vertical flight distribution of 

adult western corn rootworms in Iowa cornfields. Journal of Economic Entomology, Vol. 68: 

351-352