Annex to the decision: Herbicide tolerance stewardship plan as provided by the proponent

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DuPont Crop Protection and Pioneer Hi-Bred's resistance management philosophy is to provide growers with the tools they need to manage weed resistance while preserving and maintaining the cropping systems of choice. We believe in offering a broad range of product options and providing sound agronomic advice, respecting the grower's product choice, while supporting our customers and our products with appropriate stewardship.

The foremost weed management principle is to prevent weeds from competing with the crop for water, nutrients, and light, in order to protect yields. Customer needs for weed management options vary, according to weed species, crop rotations, and farming practices, so different approaches may be needed.

Weed shifts and resistance can and will occur, therefore good stewardship of herbicides and a prudent utilization of herbicide tolerance technologies is essential.

Fundamentals of Sustainable Weed Management

The most important principle of weed resistance management is to prevent the survival and spread of resistant populations. The key fundamentals are:

  1. Use an effective alternate mode of action (MOA) to control known herbicide-resistant weeds
  2. Include effective alternate MOA at least every-other year for "at-risk" weeds
  3. Scout fields to monitor effectiveness of the herbicide program

The following are additional considerations growers should choose to incorporate into their farming practices to manage weed resistance.

  1. Utilize herbicides with multiple modes of action effective on target weeds, including those with residual, before glyphosate applications and/or tank-mix another herbicide with glyphosate.
  2. Utilize cultural practices such as cultivation, other mechanical weed management practices and crop rotation.
  3. Apply herbicides at labelled rates and at the recommended stage of weed growth as stated on the label.
  4. Seed genetics should be selected based on agronomics, desired traits and yield potential.
  5. Purchase of a herbicide-resistant hybrid or variety does not limit the grower to use only one herbicide system. Conventional herbicides can and should still be a part of the grower's overall weed management system.
  6. Growers utilizing herbicide programs including, glyphosate and/or ALS chemistries, with herbicide tolerant crops can do so on an annual basis provided the technology is managed effectively.
  7. Fields should be scouted before and after herbicide applications and at harvest.
  8. Equipment clean-out is essential to reduce the spread of resistant weed seed.

Alignment with Crop Protection Industry Best Practices

The above beliefs are shaped through our collaboration with the Herbicide Resistance Action Committee (HRAC). HRAC is an industry initiative which fosters co-operation between plant protection manufacturers, government, researchers, advisors and farmers. The objective of the working group is to facilitate the effective management of herbicide resistance. HRAC membership includes BASF, Bayer, Dow, DuPont, FMC, Monsanto, and Syngenta.

These, and many additional facts and recommendations about managing weed resistance, can be found at the HRAC website.

Alignment with Weed Science Community

The fundamentals of sustainable weed management presented here are shaped by and aligned with the general thinking of the academic community of the university system, as agreed for example in documents of the "Glyphosate, Weeds, and Crops Group". Members are university weed scientists from major corn and soybean producing states who have been working on weed management in glyphosate-resistant cropping systems.

View substantial technical background and detailed information about Weed management - PDF (1,863 kb).

Examples of Herbicide Tolerant Soybean or Corn Weed Control Programs

A spring application of 2,4-D is an effective way to prevent the proliferation and spread of glyphosate and/or ALS-resistant Canada Fleabane. For control of annual weeds like redroot pigweed or lamb's-quarter's, use a chloroacetamide containing product such as DuPont™ Battalion™ or an HPPD herbicide such as Callisto or Impact, or a synthetic auxin like dicamba in-crop.

A farmer can utilize glyphosate and ALS herbicides repeatedly in subsequent years on any given field, just as triazine herbicides continue to be useful weed control tools despite widespread triazine-resistance, providing they are used prudently.

DuPont Crop Protection offers a wide variety of herbicide choices including both conventional and herbicide tolerant weed control programs. Any grower who chooses to plant a hybrid/variety containing a herbicide resistance gene is not limited to use of the specific herbicide for which the gene confers resistance; conventional herbicides can and should also be used to minimize the potential for weed shifts/resistance and provide diversity in a grower's weed control options. A program using DuPont™ Accent®, Accent® Total, Assure® II, Battalion®, Classic®, Lorox®, Pinnacle® or Ultim® Total, brand products can be used on herbicide-tolerant or conventional hybrids/varieties.

Two-Pass Soy / Two-Pass Corn

Best overall crop management strategy – weed/crop competition, risk management, weed control, weed resistance management.

Soy Program (no/reduced-till) Corn Program (conventional tillage) Program Considerations

Spring burn-down with residual activity

followed by –

POST – Glyphosate alone or mixtures

PRE – Glyphosate & Boundary (S-metolachlor & metribuzin)
POST – Guardian™ (glyphosate & Chlorimumuron ethyl) (Assure II can be added for volunteer corn control)

Reduced rate PRE-grass/broadleaf weed

followed by –

POST – Glyphosate alone or mixtures

PRE – Primextra, low rate (S-metolachlor & atrazine) 
POST – Glyphosate & Marksman (dicamba & atrazine)

Two-pass programs can assist in achieving proper timing of herbicide applications, best overall weed control, and best long-term weed resistance management. Provides multiple modes of action on grass and broadleaf weeds in each cropping season. Choose non-glyphosate products based on overall efficacy on weeds likely to be missed by glyphosate alone due to weed resistance or weed population shifts.

Continuous Corn or Continuous Soy

Continuous mono-crop with sole utilization of glyphosate maximizes selection pressure for weed shifts/resistance. To minimize weed/crop competition and weed shifts/resistance (see above), use 2-pass programs that offer multiple modes of action on all key weeds.

One-Pass Soy / Two-Pass Corn

Addresses the early season weed competition in corn, while also reducing the glyphosate selection pressure on certain weeds prone to resistance.

Soy Program (conventional tillage) Corn Program (conventional tillage) Program Considerations

Glyphosate alone or mixtures – full rate POST

Guardian (glyphosate & chlorimuron ethyl)

Reduced rate PRE-grass/broadleaf weed

- followed by –

Glyphosate POST alone or mixtures

PRE – Prowl ⅔ rate & Marksman ⅔ rate
POST – Glyphosate

Preemergence herbicide manages early weed pressure and offers a second mode of action to reduce the potential for weed resistance in grasses and certain small-seeded broadleaves. Choose PRE products with activity on targeted grasses and broadleaf weeds most likely to escape glyphosate alone. Also expands POST application window.

Glyphosate alone or mixtures – full rate POST

Guardian (glyphosate & chlorimuron ethyl)

Full rate PRE-grass

- followed by –

Glyphosate POST – full or reduced rate mixtures

PRE –Prowl ⅔ rate & Marksman ⅔ rate
POST- Galaxy™ & atrazine (glyphosate & rimsulfuron & atrazine)

Appropriate for acres where difficult-to-control grass weeds are present (e.g. woolly cupgrass), or weather conditions are such that PRE herbicides alone are unlikely to offer full-season control. Full-rate PRE products with both grass and broadleaf weed activity will reduce the potential for weed resistance.

Two-Pass Soy / One-Pass Corn

Addresses the early-season weed competition in soybeans, but may require additional management in corn.

Soy Program (no/reduced-till) Corn Program (conventional tillage) Program Considerations

Fall-applied burndown (with or without spring residual activity)

- followed by –

Glyphosate alone or mixtures – full rate POST

FALL – Glyphosate & 2,4-D
SPRING POST – Guardian (glyphosate & chlorimuron ethyl)

Glyphosate alone or mixtures – full rate POST

Glyphosate & Callisto

Appropriate for fields where heavy winter annual weed pressure exists and spring burn-down applications may be delayed. Best suited for managing winter annuals prior to development of "green mulch" that covers the soil and slows warm-up/drying in the spring. Program will not reduce the potential for weed shifts/resistance among summer-annual weeds unless the product used delivers significant residual control into the spring.

Spring applied PRE (with or without winter annual burndown)

- followed by -

Glyphosate alone or mixtures – full rate POST

PRE – Conquest & glyphosate (Imazethypyr & metribuzin)
POST – Guardian (glyphosate & CE)

Full rate Pre product

Primextra & Callisto (S-metolachlor, atrazine, mesotrione)

Some winter annual weeds such as dandelion, horseweed/marestail, henbit, chickweed, etc. are often difficult to control with glyphosate alone, so include burndown herbicides with efficacy for those weeds. If ALS herbicide-based burndown programs are used in areas with ALS-resistant winter annual weeds, always tank mix with products having a second mode of action. Program will not reduce the potential for weed shifts/resistance among summer-annual weeds unless the product used delivers significant residual control into the spring.

One-Pass Soy / One Pass Corn

Total post-emergence (POST) weed control programs can be very effective and easier to execute and are more efficacious when they contain residual components.

Soy Program (conventional tillage) Corn Program (conventional tillage) Program Considerations

Glyphosate alone – full rate POST


Glyphosate alone – full rate POST


Not recommended due to increased potential for weed shifts/resistance. If used, Program may require a second POST glyphosate application. Do not use in areas where glyphosate resistant weeds have already been identified.

Glyphosate alone – full rate POST


Glyphosate + PRE-grass tank mix POST

Galaxy (glyphosate & rimsulfuron)

Is an option where improved season-long grass control is needed in corn. Use in areas where no glyphosate weed resistance issues have been identified and weed resistance monitoring programs have been established.

Glyphosate + broadleaf weed tank mix POST (as needed)

Guardian (glyphosate & CE)

Glyphosate + broadleaf weed tank mix POST (as needed)

Galaxy & atrazine

Is an option where glyphosate-tolerant broadleaf weeds are found (i.e. horseweed/marestail, buckwheat, mallow, waterhemp, morning glory, hemp sesbania, etc.). Potential weed shifts among grass weeds may still occur with this program. Weed resistance monitoring programs should be established.

Control of volunteer glyphosate tolerant corn in a soybeans can be achieved by the use of Assure® II herbicide. See label for recommended rates and time of application.

Control of volunteer glyphosate-tolerant corn within a glyphosate-tolerant corn crop requires considerations similar to volunteer conventional corn within a conventional corn crop, including hybrid selection to avoid ear loss from wind and insects, potential cultural practices like winter grazing and stale-seedbed approach to planting, mechanical in-crop cultivation, and post-directed non-selective herbicides.

The DuPont Oval, DuPont™, The miracles of science™, Accent®, Assure® II, Accent® Total, Battalion®, Classic®, Galaxy®, Guardian®, Lorox®, Pinnacle® or Ultim® Total are trademarks of DuPont or its affiliates.

DuPont CPP and Pioneer Hi-Bred Service Policies

DuPont CPP

DuPont Crop Protection Products are highly effective and work consistently. However, if the DuPont products do not meet the customer's and DuPont's expectations, it's important that these concerns be addressed immediately and resolved.

DuPont handles Product Inquiries in order to achieve the following:

  • Retain customers
  • Train growers and retailers to apply the DuPont products correctly
  • Learn more about the performance of DuPont and companion products
  • Ensure the product does not pose a hazard to users or the environment
  • Confirm that the products work according to the label; where appropriate, make label changes
  • Sustain our reputation as a supplier of high quality products
  • Manage and set future customer expectations for the use of our products

A grower should do the following if use of a DuPont product did not meet their expectation:

  • In the case of weed efficacy, they should allow 14 days in order for weed control symptoms to appear
  • In the case of crop response, they should report their concerns between 3 and 10 days after application
  • Growers should first contact the retailer who supplied them the product
  • If the retailer cannot address the growers concerns, they should contact the local DuPont representative within 21 days of application of the product and provide a clear, factual accounting of the situation
  • If a grower not able to reach their retailer immediately, they should contact DuPont directly (800 667-3925;

Once the retailer has been made aware of a concern, they should do the following:

  • Provide all information that is known about inquiry and grower to DuPont up-front, including proof of purchases and returns
  • To be impartial
  • Travel with DuPont to growers to provide local information
  • Set expectations with growers on product performance
  • Prescreen product performance inquiries to identify whether it actually is a DuPont product performance issue (simple rate related or surfactant complaints based on off label uses and product performance issues that are obviously due to environmental impacts should be handled by the dealer)
  • If a retailer is not able to reach their local DuPont rep, they should contact DuPont directly (800 667-3925;

Once the DuPont rep has been made aware of a concern, they will do the following:

  • Make initial telephone contact with dealer and/or grower within a reasonable time of receipt of complaint (one (1) business day) and create an expectation of when the investigation will take place
  • At first visit, collect all information from farmer/applicator that is specified on a standard form (available upon request)
  • Verify acres purchased and the acres treated relative to the product inquiry to be sure correct rates were applied to the acres in question
  • At first visit, document as much factual information as possible
  • If possible, resolve inquiry
  • Where appropriate, and within limits, arrange for compensation to the grower
  • If not possible to resolve the inquiry, explain this to the grower and retailer and outline what more needs to be done to get this inquiry to a conclusion, including timelines
  • Inform growers of correct use of product and set expectations of product performance in relation to the pest spectrum and during challenging environmental conditions
  • Manage the information flow to allow understanding by the farmer of the situation and the root cause of his inquiry. Manage the cost if there is to be remedial action to be fair to grower and to DuPont
  • Treat all growers equitably and in a way that is defendable

Pioneer Hi-Bred

Pioneer has the ability to collect field observations regarding agronomic issues through our web-based Service Call System available to the Pioneer Fields Sales Staff across Canada. The Pioneer Service Call System allows for agronomic issues to be effectively described and transmitted from the field level directly to trained experts within Pioneer. The System works in the following manner:

  • An agronomic issue is reported to Pioneer Field Personnel by a customer
  • Pioneer Field Personnel perform an immediate on-farm follow up (preferably within two days of the call)
  • Information pertinent to the call (e.g. hybrid, growth stage, herbicide applied, etc.) is collected and entered into the web-based, Pioneer Service Call System
  • Depending on the nature of the call an e-mail notification is sent to the appropriate Pioneer expert in that field responsible for follow-up. For example service calls regarding weed resistance could be immediately sent to both Pioneer's Technical Service Team and our DuPont chemical colleagues.
  • The Pioneer expert can then review the nature of the call and download any pictures or additional documents pertaining to the agronomic issue as provided by the Pioneer Field Sales Staff
  • Based on this information the Pioneer expert could then decide on the necessary follow up steps which, in the case of weed resistance or HT failure, would mean reporting it to CFIA immediately.

Pioneer has already successfully applied this Service Call System to other registration requirements such as those for unexpected insect damage to Bt products. The Service Call system also gives Pioneer the benefit of collecting agronomic data in one central location allowing us to notice trends or potential recurring issues.

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