Weed resistance to herbicides is nothing new, but in the past 30 years, the number and spectrum of herbicide resistance have exploded and caused economic concern. In 1991, 120 weed biotypes resistant to triazine herbicides and 15 other herbicide families were documented throughout the world. Since then, nearly 500 unique cases of herbicide resistance have been reported. Some of the early herbicide resistance issues were mitigated through the development of corn and soybean crops resistant to the broad-spectrum herbicide glyphosate. However, repeated use of glyphosate over many years has led to widespread resistance of critical weeds to glyphosate. This has created a situation where farmers are concerned, and even panicked, by their inability to control weeds.
The agricultural community has responded with several strategies: the discovery of new modes of herbicidal action (which admittedly takes time to develop and register); stacked herbicide crop gene resistance (dicamba and 2,4-D, which have now reached the market) and herbicides containing multiple modes of action (some of which have been available for a number of years); and crop rotation. Each of these strategies has its own strengths and weaknesses and may not be compatible with all cropping systems.
One of the strategies that has achieved considerable commercial success in several cropping systems is to combine multiple herbicides in the same product. This approach has several advantages. By combining multiple modes of action, these products can control resistant weeds and help reduce the potential of weeds developing additional resistance. They also make the application easier for farmers, as the developers make sure that the herbicides are compatible with each other and are blended at the best ratio to achieve weed control without causing damage to the specific crop while helping to maximize yields.
Kline’s new study, Strategies to Mitigate Weed Resistance to Herbicides: U.S. Market Analysis and Opportunities, covers all the strategies and focuses on the combination of multiple herbicides in products, along with which products have been the most successful and why.