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Know Your Modes of Action

Whether applying alone or tank-mixing, it is essential to have knowledge of modes of action to help prolong product efficacy for fungicides, insecticides and herbicides. Modes of action, represented as Fungicide Resistance Action Committee (FRAC) codes, Insecticide Resistance Action Committee (IRAC) codes and Herbicide Resistance Action Committee (HRAC) codes, are typically listed on product labels.

Mixing products with different modes of action can help lessen the chance your application will lead to disease, insect or herbicide resistance:

  • Fungicides that target a specific site within a pathogen present a higher risk of developing resistance, while multi-site fungicides are classified as having a low risk potential for resistance. One example is Secure® Action fungicide, which is registered for turf in FRAC group 29 as a multi-site contact fungicide, and it has very low risk of developing resistance. Some classes of fungicides have a high risk of developing resistance to control certain pathogens. For more information, read this article from Golf Course Management magazine discussing diseases that are at a high risk for developing resistance.

  • Tank-mixing fungicides during applications ensures complete activity against the target pathogen using both fungicides, rather than partial activity against an insensitive pathogen when the higher-risk fungicide is used alone. If resistance is not an issue, tank-mixtures also help improve disease control when there is more than one target pathogen.

  • Insect resistance is less likely to occur for insects with annual life cycles, like white grubs, where genetic changes happen at a slower pace. For example, one application of Acelepryn® insecticide (group 28) in the spring is effective for season-long control of Japanese beetles and masked chafer white grubs, among other species. ​​​​​​​
  • Insects that reproduce rapidly, have multiple generations per season and are repeatedly exposed to the same active ingredient are more likely to develop levels of resistance. Examples would include southern chinch bugs in the southeastern U.S. and annual bluegrass weevil adults in the northeastern U.S. Incorporating resistant turfgrass cultivars, reducing treatment frequency and rotating modes of action for these damaging pests is critical to preserving control options in the long term. An insect control strategy should include correct identification, monitoring and action thresholds to apply control measures specific to the targeted insect.

  • Herbicides are generally tank-mixed to broaden the weed control spectrum. For example, Pennant Magnum® herbicide (group 15) can be tank-mixed with Barricade® 65WG herbicide (group 3) in warm-season turf to enhance weed control in heavy weed pressure regions. Weeds that escape herbicide applications can proliferate to cause more issues the following year. Any escapes should be controlled with a post-emergence herbicide like Monument® 75WG herbicide (group 2) or Tenacity® herbicide (group 29), or newly launched Manuscript® herbicide (group 1), or another post-emergence grass herbicide, depending on turf type.

  • Herbicides may not always have the same mode of action or activity on the same weed, so a resistance management strategy in turf is not just a tank-mix of different modes of action. A weed control strategy should employ all possible herbicide options, pre- and post-emergence applications and even non-selective and mechanical (hand removal) options to control weed escapes.

When considering which product to use to control a specific pest, it is imperative to carefully read the product label. Even though some products may belong to the same FRAC, IRAC or HRAC group, they won’t necessarily control the same diseases, insects or weeds.

The Syngenta brand portfolio offers fungicides, insecticides and herbicides with a variety of modes of action to help you prevent and manage resistance:


Visit FRAC.info to view all fungicides and their corresponding classifications.


Visit IRAC-online.org to view all insecticides and their corresponding classifications.


Visit HRACglobal.com to view all herbicides and their corresponding classifications.

Resistance management is an important consideration used in the development of Syngenta agronomic programs. These proven programs help turf become fit before the season, provide exceptional turf quality for players and recover from stress like insects, disease, heat, drought, aerification and traffic. To find an agronomic program that can assist in managing resistance for your area, visit ConditionPerformRecover.com.

Always read and follow label instructions.

©2018 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Divanem and Scimitar GC are Restricted Use Pesticides. Contend is sold as a copack of separately registered products: Contend A and Contend B. The trademarks displayed or otherwise used herein are trademarks of a Syngenta Group Company or their respective owners.