Palmer Amaranth in the Pacific Northwest

Palmer amaranth is one of the most troublesome pigweeds in crop production systems in the United States. It only recently started to appear in the Pacific Northwest (PNW). A coordinated extension and outreach effort among land grant universities (University of Idaho, Oregon State University, and Washington State University), Amalgamated Sugar, other commodity commissions, and industry was launched to track Palmer amaranth in the PNW. In 2023, tissue samples were collected from pigweeds suspected to be Palmer amaranth with tests providing confirmation. Palmer amaranth was detected in several crops as well as right-of-way and private property. Most of the Palmer amaranth populations were confirmed to be resistant to glyphosate. Additional surveys and resistance screening efforts are underway to map the distribution of Palmer amaranth and assess the level of herbicide resistance across the region. Earn 0.5 CEUs in Integrated Pest Management by reading this article and taking the quiz at https://web.sciencesocieties.org/Learning-Center/Courses.