Commercially available herbicides have been helping to protect crops for about 80 years. Among the first to be introduced were auxin herbicides. Auxin herbicides were discovered independently by American and British scientists in the 1940s1, a time when chemistry was quickly advancing. Auxin herbicides proved to be so useful they are still a foundational herbicide tool today. Corteva Agriscience has been instrumental in innovating auxin herbicides, helping to develop products that are more effective, easier to use and have a more favorable environmental profile than initial auxin herbicides developed decades ago.
Auxin herbicides—also called synthetic auxins—use chemistry to mimic a substance that occurs naturally in plants. The term auxin comes from the Greek word “auxein,” which means “to increase.” Scientists first identified natural auxins in the 1920s and discovered they are responsible for regulating plant growth. In the proper amounts, auxins stimulate plant cells to grow by elongating. But when too much auxin is present, it has a phytotoxic effect, killing plant tissue. Synthetic auxins were the first selective herbicides developed, meaning they are effective only against certain weed species. They work by disrupting multiple growth processes in the weed, eventually causing the weed to die.1-2 Auxin herbicides are very effective at controlling broadleaf weeds, especially those that plague cereal and grain crops. Weeds such as henbit, chickweed and lambsquarters can be difficult to control that starve crops of the nutrients, sunlight and water they need to produce optimum grain yield.
Weeds such as henbit, chickweed and lambsquarters are particularly difficult to control in cereal crops. Many species of broadleaf weeds are also showing resistance to glyphosate and ALS herbicides.
Auxin herbicides are classified in chemistry group 4, which are growth regulators. Some common auxin herbicide active ingredients include 2,4-D, fluroxypyr, clopyralid and dicamba. These active ingredients have been in use for decades and are still effective tools for weed control that can be found in many formulated herbicide products. However, there is always a benefit to expanding herbicide options. Innovation, even within an existing herbicide chemistry group, can improve efficacy, reduce chances of weeds developing resistance and result in a more sustainable profile for active ingredients. Arylex™ active, which was discovered and developed by Corteva, offers new innovation that builds upon the legacy of effective auxin herbicides.
Arylex active is a member of the arylpicolinate family, a new structural class within the auxin herbicides. Through specific adjustments in chemistry, Arylex is able to deliver several unique capabilities compared to other synthetic auxins:
Synthetic auxin herbicides were among the earliest and most effective herbicides available to farmers. Today, many of these active ingredients remain important tools for farmers to cultivate cleaner, more productive fields. With advances in science, Corteva is able build on past success to develop new and improved active ingredients, such as Arylex, that are more effective at lower use rates and minimize impact on the environment compared to traditional auxin herbicides. With solutions like these, farmers can continue advancing their ability to protect fields and grow bountiful crops.
*Always read and follow label and use directions.
1 “Auxin and Auxinic Herbicide Mechanism(s) of Action - Part 2 - Advanced -Overview and Objectives,” Plant and Soil Sciences eLibrary (University of Nebraska Lincoln, 2004), https://passel2.unl.edu/view/lesson/624f3e499e56/1.
2 “Synthetic Auxins,” Herbicide Symptoms (University of California Division of Agriculture and Natural Resources), accessed December 28, 2022, https://herbicidesymptoms.ipm.ucanr.edu/