Resistance Management in Canada: Best Practices for Industrial Vegetation Management

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As a professional vegetation manager, it is important to understand how weeds develop resistance and what strategies can be implemented to delay resistance.

Proper application and stewardship of vegetation management herbicides are essential to controlling target weeds and brush, and ensuring environmental, wildlife and human safety. Corteva Agriscience™ is committed to providing vegetation management professionals with the products, tools and education to get the job done right, ensuring the practices used are sustainable in the long term.

What is herbicide resistance?

Resistance is the naturally occurring inheritable ability of some weed biotypes within a given weed population to survive a herbicide treatment that would, under normal use conditions, effectively control that weed population. 

Research shows herbicide resistance is increasing globally due to the frequent use of herbicides with a similar site of action in a growing season in the same field; crop rotations that rely on similar site of action herbicides; and limited use of non-herbicide weed control options.

Herbicide resistance in Canada

Today, Canadian industrial vegetation managers have approximately eight groups of herbicides available to control target weeds on industrial sites. To date, the development of resistant weeds in industrial settings in Canada has been limited thanks to best management practices already being implemented by professional vegetation managers, such as:

  • using full rates
  • calibrating equipment to ensure proper rates are being applied
  • using high water volumes to achieve good coverage
  • spot spraying versus full broadcast application year after year
  • only using one herbicide application on most roadsides and utility rights-of-way every three to five years
  • excellent monitoring (returning to sites to ensure weed populations are controlled and managing any that have not been controlled)
  • incorporating mowing and cultural control options

Decreasing the risk of resistance

Other best management practices we recommend implementing to decrease the risk of resistance development are:

  • rotating herbicides groups (not product brand names)
  • selecting herbicides with multiple modes of action (each with activity on the target weed)
  • using herbicide mixtures containing different herbicide groups with activity on the target species (proven to be more effective than just rotating herbicides); and, if possible
  • adjusting the timing of application

Professional vegetation managers should try to avoid applying herbicides at the same time year after year, as this can potentially lead to selection of certain weed species. For example, if you are managing bare ground sites or roadsides, rotate what area you start your program in from year to year. 

Innovations for professional vegetation managers

As leaders in industrial vegetation management, Corteva Agriscience provides you with the products, tools and education to help delay resistance. Our trusted herbicide solutions deliver elite control of a broad spectrum of broadleaf weeds, brush and invasive plants.

It’s important to remember that the long-term sustainability of herbicides as an effective tool to manage vegetation is in your hands.

Watch this short video to learn more about how to delay herbicide resistance:

Or for more information about herbicide resistance and the tools available to manage vegetation on industrial sites, please contact your Corteva Agriscience IVM Expert or visit