The Pesticide Environmental Stewardship (PES) Website is sponsored by the Center for Integrated Pest Management. PES provides convenient access to information on proper pesticide handling. All subject matter contained on this site has been reviewed and posted by Pesticide Safety Education Program Coordinators and Specialists from the Cooperative Extension Service. This website is intended for a […]
Dispelling Common Misconceptions about Superweeds (fact sheet) — Weed Science Society of America Press Release 10/8/2014 International survey of herbicide-resistant weeds www.weedscience.org Farmers Battle Herbicide Resistance with Harvest-Time Weed Seed Controls — Weed Science Society of America Press Release Nov. 5, 2014 Resistance by the Numbers — PowerPoint presentation by John Stone, Michigan State University. 2015. The following […]
Herbicides are grouped according to family (e.g., triazines), the target site of action or mechanism of action (e.g., Group 5), and mode of action (e.g., Photosynthesis Inhibitor). Herbicides within a family have similar chemical structures and typically the same site or mechanism of action (MOA). Knowing the chemical family and MOA group to which an […]
If herbicide resistance is confirmed or highly suspected, diverse approaches to managing herbicide resistance need to be incorporated into weed management strategies immediately for the species in question. It is best to stop using the herbicide in question and other herbicides with the same mechanism of action. However, in many cases, the herbicide continues to […]
Early detection of resistance means management will be easier, and it increases the potential to avoid the spread of the resistant biotype. Unfortunately, because resistant plants and susceptible plants look alike, resistance often is not detected until the resistant biotype has spread to 30% or more of the field and perhaps to surrounding fields. Therefore, […]
What occurs within a resistant plant that allows it to survive after an herbicide application? What characteristics do the resistant plants possess that the susceptible plants lack? The four known mechanisms of resistance to herbicides are: Altered target site: An herbicide has a specific site (target site of action) where it acts to disrupt a […]
Weed control failures Most weed control failures are not due to resistance. Before assuming weeds surviving an herbicide application are resistant, eliminate other possible causes of poor control: Herbicide application Inadequate rate Poor spray coverage and/or incorporation Improper timing of application of postemergence herbicides (after weeds are too large to control) Failure to use an […]
Susceptibility and Tolerance Herbicide susceptibility is the degree to which a plant is subject to injury or death due to a particular herbicide. Herbicide tolerance is the inherited ability of a species to survive and reproduce following herbicide treatment. There was no selection to make the plants tolerant; those plants simply possess a natural tolerance. […]
Reversal of resistance can occur in some pest populations by allowing time between applications of a class of pesticide to permit resistant populations to become diluted by pesticide-susceptible individuals. However, no one can predict if or when resistant pests will change back to a susceptible population. The best practice is to reduce the chance of resistance developing in […]
Pesticides are substances that control various types of pests, such as weeds, harmful insects, and disease-causing organisms like bacteria and fungi. Pesticides oftentimes are the most effective and efficient pest control tools available. Resistance to pesticides is a serious, and growing, problem. Worldwide, more than 600 species of pests have developed some level of pesticide […]