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Plowed Field
Insecticides & Miticides

Reducing Resistance Goes Beyond a One Season Strategy

Originally published September 25, 2022

croplife magazine


If we’ve learned anything during the last two years, it’s that Mother Nature always finds a way to work around the best humanity has to offer. The same can be said in the agriculture industry. No matter how hard we try, resistance is always going to be an obstacle our industry will have to contend with.

Unfortunately, the agriculture industry is losing access to crop protection tools at a faster rate than new tools are being developed. Of the 31 known insecticidal modes of action, there are documented cases of resistance in 21 somewhere around the globe. This puts significant emphasis on building out detailed crop management strategies in advance and making educated product-selection decisions.

Mitigating resistance for crop diseases, pests and weeds is a challenge growers must address with a holistic approach: i.e., integrated pest management (IPM). Selecting a crop protection tool that’s going to address a target pest is not just a one-time decision — it must fit into a whole program that also matches up with the other pesticides used in a season-long rotation.

Building the Foundation of an Anti-Resistance Management Plan

Fewer tools to choose from means crop and product rotations become even more important and challenging to design. Growers and their retailer partners must be even more creative in thinking about exposures of weeds, pests and diseases to modes of action, and how pre-harvest intervals help them reach harvest. Spraying less frequently will not necessarily reduce the chance of resistance development.

The incorporation of IPM practices can help growers address this challenge by maintaining the efficacy of their management tools and making pest management more sustainable. Some regions of the U.S. are easier to implement IPM practices in than others because some crops, especially high-value fruit crops, naturally lend themselves to IPM practices and the return on investment on those practices is more apparent. High-value specialty crops tend to not have as many tools available to them and it’s tougher to get new products registered for use on those crops, putting more pressure on growers to be mindful of their crop rotations, modes of action used and application frequency. Other factors include pest pressure, pest and natural enemy ecology, crop genetics, and environmental conditions, just to name a few.

To stay ahead of resistance development, there are a few key nuances to stay aligned to.

  • Manage the timing of product applications to avoid the same generation of pests being exposed multiple times to the same mode of action. Although most pests or weeds in row crops only have one generation per season, some pests can have up to 15 generations in the same growing season.
  • Evaluate the strengths and weaknesses of each crop protection tool to ensure the chemistry works at its best based on the crop development and pest pressure at each point of the season.
  • Consider cultural practices – like cover crops, narrow row spacing of crops or increased seeding rates to get faster canopy closure – as tools to outpace or outrace pests.
  • Pay attention to what modes of action have worked in the past and determine why that approach was working at its best. A grower doesn’t want to learn about a mistake when they’re harvesting the crop. Don’t limit thinking about pest management to just the next growing season; think 3-5 years out as well.

Managing for Resistance: There’s No Silver Bullet

As we look at the landscape of how to minimize resistance development, aspects of mechanical, chemical and cultural control have to be in play. We need to use all the available tools to our advantage, while remaining good stewards. Education and good record keeping can also be excellent solutions to proactively manage resistance.

Our toolbox of available crop protection products is precious, so we need to do what we can to avoid exasperating the situation and allowing resistance to occur more quickly.