Pesticide Resistance: Does it Really Matter?

The use of modern pesticides didn’t ramp up until the late 1940’s. This era provided a seemingly unending stream of new products that became increasingly more effective, selective, and consistent. Unfortunately, it wasn’t long until products started losing their effectiveness. Pest managers were largely uninterested in resistance since new products were coming along each year, while scientist took the opportunity to study these resistant pests and better understand their physiology. For both managers and scientists, pesticide resistance didn’t really matter.

Fast forward to today and we all know that pesticide resistance is a major threat to agriculture and human health. There are weed populations in the Midwest that are currently resistant to 5 different herbicide modes of action! Likewise, mosquitos that carry serious diseases like Zika, malaria and yellow fever can develop resistance if not managed properly. How can we produce food for a growing world, protect increasing populations from mosquito borne illness, and continue to effectively use pest management tools if this trend continues?

Read The Label!

To help combat this, pesticide labels now include an entire section on Resistance Management. I am sure most of us open the label and look at PPE requirements, use rates, and re-entry requirements (hopefully!), while skipping over all the other stuff. First, you must read the entire label and secondly, understanding pesticide resistance is of critical importance and the label is a fantastic resource for understanding the prudent use of pesticides. Additionally, not all pesticides are created equal, meaning resistance happens faster with some than others. So, unless you have been extensively trained in pesticide science and know these nuances, it is critical to follow the directions in this section.

The resistance management portion of a label will discuss pesticide group numbers. The Resistance Action Committee (RAC) uses these numbers and the define pesticide mode of action. A mode of action is the unique way a particular pesticide works inside the pest. You do not need to memorize these numbers, nor fully understand how the mode of action for each number works. The key is to rotate which number you use for treatments. So, using a number 4 auxin mimic every single treatment is not a great idea. Perhaps a number 4 could be followed by a number 14 PPO inhibitor. The point is don’t use the same number over and over until it no longer works. These are the kinds of directions you can find in the Resistance Management Section. These numbers are often found in the Resistance Management section and prominently featured on the front page of a label as well.

Learn about resistance management and prepare to start each year with a strong and well-informed integrated pest management (IPM) plan that addresses your most common pests. Doing this, and using the resources found on the label, will result in more effective management while preserving the pesticides for years to come.


Author Dr. Jason Ferrell. Dr. Ferrell is a Professor at the University of Florida where he serves as Director for the Center for Aquatic and Invasive Plants and the Pesticide Information Office.

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Additional Links

Herbicide Resistance Action Committee:

Insecticide Resistance Action Committee:

Fungicide Resistance Action Committee:

Rodenticide Resistance Action Committee:

Center for Aquatic and Invasive Plants:



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Posted: June 3, 2021

Category: Agriculture, Crops, Farm Management, HOME LANDSCAPES, Horticulture, Invasive Species, NATURAL RESOURCES, Pests & Disease, Pests & Disease, Turf, UF/IFAS, UF/IFAS Extension, Water
Tags: Center For Aquatic And Invasive Plants, Jason Ferrell, Pesticide Information Office, Pesticide Label, Pesticide Resistance, Pesticides

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