Decision Document DD2004-48
Determination of the Safety of BASF Canada's  Imidazolinone-Tolerant (CLEARFIELD™) Wheat Teal 11A

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Issued: 2004-06

Appendix 1: CLEARFIELD™ Wheat Herbicide Tolerance Stewardship Plan

1. Best Management Practice Program for the CLEARFIELD™ Wheat Production System


The CLEARFIELD™ Production System for Wheat is an innovative cropping system that offers a new way to grow wheat and enhanced weed control. It creates a number of new opportunities to western Canadian producers:

  • Superior, one pass, broad-spectrum control of grass and broadleaf weeds with ADRENALIN Herbicide.
  • Ability to control volunteer wheat (off types) and barley in crop. This allows for flexibility in cropping rotations.
  • An additional weed management tool for weed control and resistance management.
  • Maintain glyphosate as an effective pre-seed tool
  • Gives processors access to pure wheat

Key sustainability issues

The users, developers and marketers of herbicide tolerant cropping systems are responsible for sustaining the production system and must address the key issues of:

  • Herbicide resistance management using an integrated approach.
  • Control of herbicide tolerant crop volunteers.
  • Managing out-crossing to non-CLEARFIELD™ crops and weeds.

These key sustainability issues form the basis for our stewardship plans for crops grown using the CLEARFIELD™ Production System. The CLEARFIELD™ Wheat Stewardship Plan, like those for other CLEARFIELD™ crops, can be summarized by the following guiding principles:


There are a number of GUIDELINES that must be understood and followed by Agronomists and Growers when using CLEARFIELD™ Production Systems.

  • DO NOT exceed a maximum of 2 exclusive Group 2 herbicides on any one field, in any 4 year period
  • ALWAYS follow an Integrated Weed Management (IWM) program that includes herbicides, cultural practices and crop rotations in order to manage weed populations and minimize weed seed development
  • ALWAYS control volunteers in the season following a CLEARFIELD™   crop
  • USE practices which minimize the likelihood of out-crossing to similar crops or related weeds

FOLLOW the Best Management Practices outlined in the our CLEARFIELD™   Wheat Stewardship Guide

Resistance Management in the CLEARFIELD™ Production System

Herbicide resistance management using an Integrated Weed Management (IWM) approach

The objectives of herbicide resistance management are to achieve weed control while preserving the value of each herbicide and each herbicide group for the longer term.

An integrated approach to weed control is the Best Management Practice to delay the onset of weed resistance to herbicides. An integrated approach involves the use of all methods available to the grower in order to provide effective weed control in crop. The use of herbicides is one of a number of useful tools available to growers.

Development of Resistance

Herbicide Resistance Action Committee (HRAC) is an industry initiative which fosters co-operation between plant protection manufactures, government, researchers, advisors and farmers. The objective of the working group is to facilitate the effective management of herbicide resistance. HRAC has identified a number of factors to consider when evaluating herbicide resistance risk. The most important factors influencing a plant's potential to develop resistance are:

Biology and genetic make up of the weed species in question: Points of consideration include the following. Weeds that are extremely susceptible to an herbicide, are prolific seed producers and have a large amount of genetic variation within the species may have a greater potential to become resistant to an herbicide. The initial frequency of naturally occurring resistant biotypes in a weed population influences a weed population's potential to develop resistance. Also, the relative fitness or vigor of resistant weed biotypes affects resistance development. Generally speaking, for any particular weed species, the greater the initial frequency of resistance and the greater the fitness of the resistant biotype, the greater the potential for herbicide resistance to develop.

History of herbicide use: continuous use of the same mode of action herbicide for several consecutive years, without tank mixing or sequentially applying herbicides with other modes-of-action, may increase the risk for resistant populations to develop. The greater the selection pressure exerted by an herbicide, the greater the potential for resistance. Although a higher rate of application or sequential applications results in a high level of weed control, it also represents an increased potential for the development of resistance. Likewise, lower herbicide rates, which provide less effective weed control, exert less selection pressure. Label herbicide rates are a reflection of efficacy trials that indicated best control and crop yield responses.

Crop management practices: weed control that relies solely on herbicide use and does not combine tillage or other cultural practices with herbicide applications may increase the potential for resistant populations to develop. This includes using crop rotation practices that allow for non-chemical options for weed control as well influence the ability to rotate herbicide type and frequency of use.

Environmental conditions: environmental conditions that are not conducive to herbicide breakdown in the soil may increase the potential for resistant populations to develop. Continuous dry weather can slow the breakdown of many herbicides (e.g. imidazolinones). High soil pH inhibits the breakdown of some herbicides like SU's. The longer a herbicide persists, the longer it exerts selection pressure on a weed population, particularly if there are multiple weed flushes in one growing season.

Weed seed bank/Seed soil dormancy: a high soil seed bank within an individual field increases the selection pressure, which in turn increases the likelihood of resistance developing. Seed soil dormancy will also impact on resistance development. Plants with longer soil dormancy will tend to exhibit slower resistance development since selection pressure is reduced. Seeds that can survive for years in the soil may slow the onset of resistance. Weeds with a long seed life may create a large seed bank in the soil. This seed bank serves as a buffer against genetic changes in the weed population, since the seeds do not normally all germinate within one year. Conversely, weed seed with a short seed life germinate within one or two years. This rapidly depletes the quantity of susceptible weed seed and gives any resistant seed a competitive advantage when a selection pressure is applied.

Many exceptions to these generalizations exist, and this makes it difficult to predict which species will develop a resistant population. The time required for a weed population to develop resistance will vary, and depends on many factors, including:

  • Selection pressure exerted by the herbicide;
  • Herbicide rotation patterns;
  • Seed germination dynamics;
  • Use of herbicide combinations with different modes of action;
  • Initial frequency of naturally occurring resistant individuals in the weed population; and
  • The relative vigor of resistant biotypes of weeds.

Based on these factors, models have been developed to predict the development of resistance in a weed population. Current models provide an indication of the development of resistance; these indications are an essential input to the development of resistance management strategies and practices.

Identifying Weed Resistance

It is important to avoid confusing herbicide failure caused by weed resistance with herbicide failure caused by other factors. All other possible reasons for poor herbicide performance should be ruled out before considering the possibility of resistance. These include application error and poor environmental conditions at the time of herbicide application. Shifts in weed populations from susceptible species to species that are less sensitive can also cause weed control problems. Herbicide resistance should be suspected under the following conditions:

  • A weed species that is normally controlled by the herbicide now escapes treatment, while other weeds on the label are controlled.
  • Other factors such as application error or adverse weather conditions are ruled out.
  • Irregular shaped patches of a weed develop in the field and are not controlled with the particular herbicide.
  • Weed control records for the field indicate repeated use of a particular herbicide, or herbicides from the same herbicide group.

Weed Resistance Management

Herbicides have been grouped based on their mode of action. Herbicides that are in Group 2 are those classed as ALS/AHAS inhibitors. BASF markets herbicides that are in the imidazolinone chemical family and they are members of Group 2. Herbicides such as ABSOLUTE, ODYSSEY and ADRENALIN used in the CLEARFIELD™ Production System are examples of Group 2 herbicides. BASF is therefore a key stakeholder in resistance management of ALS resistant weeds.

BASF is committed to maintaining the efficacy of all of its herbicides in order to provide growers with effective, high performance, environmentally sound products for many years. The key to the performance of CLEARFIELD™ Production Systems is effective weed resistance management. BASF Crop Protection is committed to delivering sustainable cropping systems that incorporate best practice principles. The CLEARFIELD™ Production Systems provide alternative options for growers within a well-managed rotation. This better method practices guide is designed to assist agronomists and growers who have chosen to use the CLEARFIELD™ Production Systems, in making decisions which best manage herbicide resistance in weed populations.

Following is a discussion and proposed strategies for managing ALS herbicide resistance in weed populations under the CLEARFIELD™ Production System. The guidelines for managing the development of weed resistance presented here are consistent with recommendations put forward in provincial crop protection guides and WREAP.

General Recommendations to Minimize Development of Weed Resistance

Development of herbicide resistant weeds can be avoided or delayed through good management practices. The recommendations listed below take into consideration many of the points discussed so far and are designed to provide an integrated approach to weed management in order to prevent or delay the onset of weed resistance. Three key areas of integrated weed management are chemical control, cultural practices and crop management.

Chemical Control

  • Know your herbicide groups.
    Reliance on one product, or on products within the same group may eventually lead to weed resistance. Understanding herbicide classification by product group is necessary to develop an effective weed management strategy.
  • Keep records of herbicide application.
    Herbicide application records and field mapping are necessary to effectively rotate herbicide groups.
  • Always read and follow herbicide label recommendations.
    The rate of herbicide recommended provides the most effective control over a wide range of environmental conditions. This will help to ensure weed seed is not added to the seed bank, while minimizing selection pressure.
  • Use tank mixes or sequential applications of herbicides that have different modes of action.
    Tank mixes allow you to control weeds in more than one way by combining two or more modes of action on the same weed. In order to be effective, both active ingredients need to provide control of the target weed. This minimizes selection pressure and delays the development of weed resistance.
  • Rotate among herbicide groups.
    Rotate among herbicide groups for both grass and broadleaf weed control. Alternating products used according to mode of action is one of the most effective means of delaying development of weed resistance. Use the minimum number of applications of any one herbicide or herbicide group per season.
  • Utilize non-selective herbicides.
    Non-selective herbicides applied pre-emergence are an effective means of controlling early flushes of weeds and/or weed escapes. They should be used in conjunction with an in crop herbicide that has an alternative mode of action.

Cultural Control/Crop Management

Cultural (non-chemical) weed control practices do not exert any chemical selection pressure and can help to reduce the level of weeds in the soil seed bank. These practices are important components of an integrated weed control strategy.

  • Use crop rotations, notably rotations from broadleaf crops to grass crops.
    Different crops can help to alter the weed spectrum. It also makes it easier to rotate between herbicide groups.
  • Plant competitive crops.
    Crops vary in their ability to compete with weeds. Crops such as barley that establish a heavy stand are much more competitive with weeds then crops such as lentils or flax. A competitive crop can reduce weed pressure.
  • Delay planting.
    Delayed planting will allow for the initial flush of weeds to germinate. This flush can be controlled with cultivation where practical, or through the use of a non-selective herbicide.
  • Plant quality seed/Increase your seeding rate
    Certified seed offers a number of benefits and helps to ensure a uniform stand that will compete more effectively with weeds. A more dense plant canopy offers more weed competition.
  • Combine tillage and/or timely cultivation with herbicide treatments, if practical.
    If your crop production system includes spring cultivation, seed as soon as possible after working the ground to give the crop a head start over the weeds.

An effective weed management strategy is comprised of multiple weed control options. Herbicide tolerant cropping systems provide yet another mechanism for effective weed control and should be considered as one of the tools for managing the development of weed resistance.

Integrated Weed Management (IWM) in the CLEARFIELD™ Production System

CLEARFIELD™ Production System crops are tolerant to the imidazolinones, which are Group 2 herbicides. Group 2 herbicides work by inhibiting acetolactate synthase, an enzyme that is required for the production of the amino acids leucine, isoleucine and valine in plants. Group 2 herbicides are known as 'ALS inhibitors'.

Continuous use of Group 2 herbicides may result in the selection of weed biotypes with a resistance to this Group of herbicides. Preservation of the effectiveness of this Group of herbicides is vital for efficient and cost-effective agricultural production in Canada. Therefore effective management strategies for weed control delay or avoid the potential for the development of resistant weeds is an important focus of the CLEARFIELD™ production system.

The CLEARFIELD™ Production System for wheat currently exclusively utilizes the herbicide ADRENALIN. This CLEARFIELD™ herbicide combines herbicides with two modes of action. The two active ingredients are imazamox (Group 2) and 2,4-D ester (Group 4). These two herbicides have both have activity on a number of the target weeds in wheat. As outlined earlier, combining two modes of action is an effective means of delaying the onset of herbicide resistance.

In addition to the general recommendations outlined in the previous section, a number of specific management strategies outlined below, should be followed when using the CLEARFIELD™ Wheat Production System. Growers and agronomists should give consideration to each of the following points, in order to determine an integrated weed management plans utilizing CLEARFIELD™ wheat within their crop rotation.

  • Make only one application of a Group 2 herbicide per season.
  • Apply no more than two (2) Group 2 herbicides in any four (4) year period on the same field. The use of no more than two applications in four years will slow the development of resistance. Consideration should be given to less frequent use to delay the onset of resistance development. This includes the use of Group 2 herbicides both within the CLEARFIELD™ Production System and in conventional crops.
  • If a Group 2 herbicide has been applied as a pre-emergence application, DO NOT apply further Group 2 herbicides to that crop. Make any further post-emergence applications with herbicides from a different mode-of-action group.
  • Where it is possible, care should be taken to avoid applications of Group 2 herbicides in consecutive years unless at least two years previous effective weed control has been achieved, with methods other than the use of Group 2 herbicides.
  • Farm practices, herbicide and crop rotations should be developed which allow for the use of alternative mode of action herbicides.
  • Where Group 2 resistance is suspected within a weed population, testing of the relevant weeds should be carried out prior to the use of crops in the CLEARFIELD™ Production System.
  • Integrated Weed Management should be undertaken on a field-by-field basis. Specific field planning should take into consideration the history of the field well as the future use options.
  • Resistance management guidelines for other herbicide mode of action Groups should be taken into account when developing and planning rotations.

Controlling Volunteers from CLEARFIELD™ wheat

Objective: control of all volunteers from CLEARFIELD™ crops before flowering.


  • Best Management Practice is to control volunteer plants in the year following when a CLEARFIELD™ Production System crop has been grown.
  • Do NOT rely on Group 2 herbicides to control volunteers.
  • Volunteers from CLEARFIELD™ crops will be controlled by all herbicides currently registered for control of conventional crops, except for imidazolinone herbicides. CLEARFIELD™ Wheat volunteers will be controlled by glyphosate, ethalfluralin, glufosinate ammonium and a range of Group 1 herbicides.
  • Clean up of farm equipment during all stages of sowing, harvesting, storage and transport are important in the effective control of volunteers.
  • Best Management Practice is to make volunteer control part of weed, pest and disease management strategies for the farm.

Important reasons for control of volunteers

  • Volunteer plants act as competitive weeds in following crops or pastures.
  • Volunteers may be important in the build-up and spread of major diseases.
  • Volunteers increase the risk of herbicide tolerance spreading from cross-pollination of volunteer plants and conventional plants of the same crop species in neighboring fields.

Controlling volunteers

A number of cultural and chemical control options are available to control volunteers including:

  • Minimize seed losses at harvest
    • Close attention to timeliness of harvesting.
    • Correct adjustments in the header.
    • Seal all holes and cracks in harvesting equipment which allow spillage, even of small quantities of seed, (especially in the table, front elevator and grain tank).
  • Clean out harvest equipment before switching fields.
  • Practice good hygiene at harvest and during transport of grain.
  • Practice good stubble management after harvest in light of crop rotation decisions.
  • Use pre-seed glyphosate application to control weeds and volunteers that emerge prior to seeding.
  • Control ALL volunteers in following crops with proper selection of in-crop herbicides.

Management actions

Keep good field records of herbicides used in previous crops and herbicide-tolerant varieties in neighboring fields to develop effective plans for controlling volunteers.

A crop of the same species should not follow a CLEARFIELD™ crop, as controlling volunteers within the same crop species is difficult. Generally speaking, this would also not be a good agronomic practice for disease and weed management.

Managing out-crossing to non-CLEARFIELD™ crops and weeds

What is out-crossing and gene flow?

Gene flow is the movement of gametes, zygotes (seeds), individuals, or groups of individuals from one place to another and their subsequent incorporation in the gene pool of the new locality (Slatkin, 1987). Gene flow is a natural biological process and in plants it primarily occurs via pollen or seed dispersal (Levin and Kerster, 1974). The relative importance of gene flow to population genetic structure depends on the distance between donor and recipient populations, population size, how long the process has been in effect, and whether the new gene confers any fitness advantage to the recipient population (Waines and Hegde, 2003).

Out-crossing (or cross-pollination) is a type of mating in plants in which a male gamete of one individual fertilizes a female gamete of another individual (Waines and Hegde, 2003). The term out-crossing generally refers to mating within a species and the term has been used synonymously with gene flow (Gleaves, 1973; Handel, 1983). However, as defined earlier, gene flow can occur through means other then cross-pollination. We will restrict this discussion to pollen-mediated gene flow (out-crossing).

A wide range of factors influence the ability of a given plant to out-cross with others, including spikelet formation, timing of flowering, stigma receptivity, pollen production, pollen dispersal, pollen viability and environmental factors. The likelihood of out-crossing varies greatly from species to species and variety to variety. Successful out-crossing may result in the offspring displaying characteristics of both parent plants.

The risk of out-crossing can vary between crop and weed species. The focus for management must be on the control of volunteers and managing herbicide tolerant crops and related species.

Potential for out-crossing in CLEARFIELD™ Wheat

While wheat is a predominantly self-pollinating crop, it is recognized that low levels of out-crossing can occur (Allan, 1980). Specific information is provided here in relation to possible out-crossing of resistant traits to other wheat varieties and related species.

Description of Triticum aestivum varieties with CLEARFIELD™ Technology

CLEARFIELD™ wheat varieties have tolerance to the BASF imidazolinone herbicide, ADRENALIN®. CLEARFIELD™ wheat, was derived from inbreeding and chemically induced modification. It was not derived from recombinant DNA technology, i.e. it is not genetically engineered (GE). This variety was developed via conventional backcrossing methods and is in the CWRS class.

Potential for out-crossing to species related to wheat

Close relatives of wheat in Canada are limited to diploid wheat T. monoccum and tetraploid wheat T. turgidum var. durum (durum wheat). There are only a few reports concerning natural cross hybridization with related species and genera. Hybridization within the genus Triticum has been shown to be generally less than 6%. Wheat is primarily self-pollinated and the potential for out-crossing with a related species is unlikely. There are no known wild Triticum species to exist in North America.

A well-known inter-generic combination involving wheat is triticale, derived from crossing between wheat and rye (Secale cereale). There have been no eports of triticale serving as a bridge for hybridization with other wild grass species.

The risk for gene flow between wheat and weedy relatives is extremely low. There are a number of weedy relatives of wheat present in Canada from the genera Aegilops, Agropyron, Secale, Haynaldia, Hordeum and Elymus. Complex (artificial) hybrids have been made between wheat and several weedy relatives. However, it has only been achieved through deliberate cross-pollination in controlled environment settings. There have been no known naturally occurring hybrids or derived species reported.

Potential for out-crossing to non-CLEARFIELD™ wheat varieties

Although wheat cultivars are classified as self-pollinators, out-crossing in spring wheat has been documented at very low incidences. In ten Canadian spring wheat cultivars, out-crossing rates ranged from 0% to 6.7% in adjacent rows (Hucl, 1996). In another study, Hucl and Matus-Cadiz (2001) examined gene flow in four wheat cultivars. In this study, maximum gene flow in adjacent rows (30 cm distance) ranged from 0.2% to 3.8%. Typically when describing average out-crossing rates in wheat an average out-crossing frequency of <1% is used. This percentage is based on the Hucl (1996) study where the average out-crossing rate of ten cultivars over two years was 0.88% at a 20 cm distance from the pollen source. Comparatively, canola has relatively high out-crossing rates with an average out-crossing frequency of 20%.

As indicated earlier, a wide range of factors influence the ability of a given plant to out-cross with others, including spikelet type, timing of flowering, stigma receptivity, pollen production, pollen dispersal, pollen viability and environmental factors. We have very briefly tried to describe how some of these factors can influence out-crossing in spring wheat.

  • Spikelet type

In ten Canadian spring wheat cultivars, out-crossing rates ranged from 0% to 6.7% in adjacent rows (Hucl, 1996). In this study, the variety Oslo that has open spikelets produced one of the highest out-crossing rates, while cultivars such as CDC Makwa and Columbus, which have dense spikes, had the lowest out-crossing rates.

  • Flowering time

Glume opening, the extrusion of anthers and the duration of opening are all significant factors affecting out-crossing. The most important factor that influences cross-pollination and potential gene flow during anthesis is the extent to which the flower opens (Waines and Hegde, 2003). In the same study mentioned earlier, Hucl (1996) demonstrated that cultivars with high out-crossing rates tended to have greater floret opening at anthesis.

  • Stigma receptivity

Stigma receptivity decreases gradually from the moment of flower opening and has been shown to range from 2 to 13 days after anthesis (De Vries, 1971). The wide range in receptivity has been attributed to environmental conditions and is longest under moderate temperature and humidity.

  • Pollen production

Waines and Hegde (2003) discussed the role environment plays in effecting anthesis and seed set. In summary, the elimination of plant stress during flowering and the early stages of seed development will diminish the success of gene flow, and will favor self-pollination.

  • Pollen production and viability

Pollen production in self-pollinating plants like wheat has been demonstrated to be much less then open-pollinated crops like rye. Wheat plants were demonstrated to have only one tenth the pollen production of rye plants (D'Souza, 1970). Under optimum field environmental conditions, wheat pollen viability was approximately 0.5 hours (D'Souza, 1970; De Vries, 1971).

  • Pollen dispersal

Wheat pollen is relatively heavy compared to other grass pollen (Lelley, 1966). In addition humidity, temperature and wind play a role. Humid weather makes pollen heavy and will reduce dispersal distances from the plant. Dry hot weather causes desiccation and reduces pollen viability. Wheat pollen travels relatively short distances. Jensen (1968) reported that 90% of wheat pollen remains within 6 meters of its source. Hucl and Matus-Cadiz (2001) examined gene flow of 4 wheat cultivars over distance and also examined the impact of wind direction. For the four cultivars, the maximum gene flow rates were recorded at the shortest distance of 30 cm from the source (adjacent rows) and were found to range from 0.2% to 3.8%. Gene flow rapidly decreases as distance from the source increased. At a 27-meter distance, gene flow was observed in only 2 of 32 samples (0.09%). These types of studies have formed the basis for the 30-meter reproductive isolation distances from all wheat species and wheat volunteers when conducting for confined field trials of wheat.

CLEARFIELD™ wheat is a CWRS wheat developed from the same germplasm pool reflected in the Hucl (1996) study. Out-crossing rates for CLEARFIELD™ wheat lines should be within the range reported in this study.

There have been no reports showing that Triticum aestivum exhibits characteristics of a pest or is a weed in Canada. Centuries of breeding of wheat varieties has selected for a number of traits, which give our modern wheat varieties a poor ability to survive in the wild. Traits such as heads that did not shatter were favored due to easier harvest but this trait placed the wheat plants at a disadvantage to plants of other species, which could more efficiently distribute seed. In addition, hull-less type plants were easier to thresh but exposed the developing seed to environmental extremes.

Despite these disadvantages, plants of modern wheat cultivars are occasionally found in uncultivated fields and roadsides. These occurrences are usually associated with grain dropped during harvest or transport. Plants growing in these environments do not persist and are usually eliminated by mowing, cultivation, and/or herbicide application.

Wheat plants can also grow as volunteers in a cultivated field following a wheat crop. Volunteer wheat plants that germinate in a crop or summer fallow following the use of CLEARFIELD™ crops should be controlled before flowering, as outlined in the Controlling Volunteers section of these Stewardship Guidelines. After almost 200 years of cultivation in Canada and throughout the world, there have been no reports of wheat becoming an invasive pest.

The preceding discussion demonstrates that out-crossing to other wheat varieties is possible, however the likelihood of this occurring can be minimized if good hygiene and rotation practices are followed and if volunteers are controlled prior to flowering.

Managing out-crossing of CLEARFIELD™ wheat to related species

As stated, the likelihood of out-crossing to related species is low for wheat. However the following practices should be followed to help in minimize the potential for out-crosses occurring.

  • Control all volunteers in the season after growing CLEARFIELD™ Wheat. (Refer to earlier section, Controlling Volunteers with CLEARFIELD™ Technology).
  • If consecutive wheat crops are grown (of which one is CLEARFIELD™ Wheat), do not save seed from the second crop. Saved seed may contain both varieties, which may increase the likelihood of out-crossing when next planted.
  • Do not plant CLEARFIELD™ wheat adjacent to other wheat cultivars
  • Maintain hygiene along fence-lines where different wheat varieties may germinate.
  • Cover loads during transport to avoid dispersing seed.

2. Communication to growers

BASF will utilize a number of vehicles to communicate the general recommendations of the CLEARFIELD™ Wheat Stewardship Plan to growers:

  • Wheat growers wishing to have access to CLEARFIELD™ wheat technology must sign a CLEARFIELD™ Wheat Commitment. This is a no fee user agreement that by signing, the grower agrees to a number production practices necessary to steward the technology. The CLEARFIELD™ Commitment contains clauses that pertain to CLEARFIELD™ stewardship. By signing this agreement, growers agree to follow the production practices outlined in the CLEARFIELD™ Wheat Stewardship Plan.
  • The only way for a grower to access the technology is to sign a CLEARFIELD™ Commitment. Therefore BASF will be able to establish a database containing the names of each grower utilizing the CLEARFIELD™ wheat production system. This will allow us the ability to communicate our stewardship plan directly to each grower accessing the technology. This can be achieved through a variety of means, including direct mail, direct grower calls by BASF Business Representatives, BASF Technical Service Specialists or personnel from BASF Ag Solutions (our customer service group).
  • In addition to direct grower contact, the CLEARFIELD™ Wheat Stewardship Plan will be widely disseminated through a number of means including promotional literature, technical bulletins and other advertising and posting on the BASF web site.
  • BASF plans to utilize training as an effective means of communicating our stewardship plans across all CLEARFIELD™ crops. This not only is an effective means of communicating the stewardship plans, it also creates advocates that support the plan and aid in its' communication and adoption. BASF stewardship training will be provided to growers, retailers, and extension agronomists. An effective stewardship plan should garner the support of key academics specializing in the area. Therefore, there should be numerous sources of information on CLEARFIELD™ stewardship available to the grower.

Communication with our end use customer is extremely important to maintaining a high level of customer satisfaction. Currently there are a variety of options available to growers to contact the company to address questions, request information, or to report problems. These options have been demonstrated to be effective, and have allowed BASF to adopt a policy committing we will respond to Customer Care Inquiries (product performance inquiries) within 48 hours of receiving a call. Growers will use the same means of communication to report problems associated with our stewardship recommendations. Growers communicate with BASF in a variety of ways, including:

  • Contacting their local BASF Business Representative
  • Contacting their agricultural chemical retailer or distributor
  • Contacting seed partner business representatives
  • Calls to our Ag Solutions toll free call center
  • Contact BASF through professional agronomists
  • Utilize the BASF web site

3. Monitoring activities

  • On a macro level, BASF utilizes numerous forms of market research and other sources of information to gain an understanding of grower production practices. Some of the relevant sources of information on grower production practices include market research information provided by companies such as Stratus Market Research and Ipsos Reid, BASF grower surveys, weed survey and production management surveys conducted by AAFC and provincial crop insurance database information. Yearly market research will illustrate market share of imidazolinone products in each major field crop. This information can be used to gauge grower adoption of the technology.
  • In addition to looking at production practices at a macro level, the grower database created through the CLEARFIELD™ Commitment allows BASF to follow stewardship practices of individual growers that have accessed the technology. We have the ability to conduct production practice surveys directly with CLEARFIELD™ wheat growers. One of the clauses in the CLEARFIELD™ Commitment stipulates that BASF is allowed to conduct in-season audits of with CLEARFIELD™ wheat growers. This will allow us to monitor grower production practices and make stewardship recommendations.
  • BASF Business Representatives and BASF Technical Specialists maintain grower contact and will be a source of information on the effectiveness of our stewardship plans.
  • We will also receive feedback on our stewardship plans from a variety of external sources such as extension agronomists, retail agronomists, provincial crop and weed specialists and our seed partner business representatives and/or agronomists.


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De Vries, A. Ph. 1971. Flowering biology of wheat, particularly in view of hybrid seed production-A review. Euphytica 20:152-170.

D'Souza, V. L. 1970. Investigations concerning the suitability of wheat as pollen-donor for cross-pollination by wind compared to rye, Triticale, and Secalotricum. Z. Pflanzenzuecht. 63:246-269.

Gleaves, J.T. 1973. Gene flow mediated by wind-borne pollen. Heredity 31:355-366.

Handel, S.N. 1983. Pollination ecology, plant population structure, and gene flow. P. 163-211. In L. Real (ed.) Pollination biology. Academic Press, Orlando, FL.

Hucl, P. 1996. Out-crossing rates for 10 Canadian spring wheat cultivars. Can. J. Plant Sci. 76:423-427.

Hucl, P., and M. Matus-Cadiz. 2001. Isolation distances for minimizing outcrossing in spring wheat. Crop Sci. 41:1348-1351.

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Levin, D.A., and H.W. Kerster. 1974. Gene flow in seed plants. Evol. Biol. 7:139-220.

Slatkin, M. 1987. Gene flow and the geographic structure of natural populations. Science (Washington, DC) 236:787-792.

Waines, J. G., and S.G. Hegde. 2003. Review and Interpretation. Intraspecific gene flow in bread wheat as affected by reproductive biology and pollination ecology of wheat flowers. Crop Sci. 43:451-463.

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