2024 CWSS-SCM Virtual AGM
Where: Virtual Meeting (Zoom) – Agenda with a Zoom link click here
When: November 26, 2024 from 12:00 pm to 4:00 pm EST
Symposium: there will be a short symposium highlighting the articles published in our recent special issue.
The speaker bios and the titles/abstracts of their presentations:
Title: Optimizing Molecular Assays for Glyphosate and ALS-Inhibitor Resistance Diagnostics in Four Weedy Species
Dr. Eric Patterson is an Assistant Professor in Weed Science in the Department of Plant, Soil, and Microbial Sciences at Michigan State University where he teaches weed science to Undergraduate and Graduates. His research focuses on more basic aspects of weed science including weed genomics, molecular biology of resistance mechanisms, rapid molecular weed diagnostics, and herbicide mode of action discovery. His lab is especially interested in how genome rearrangements (i.e. transposable elements and copy number variation) form and are utilized as novel sources of genetic variation for weed adaptation to abiotic stresses.
Abstract: Herbicide-resistant weeds pose a threat to food production in modern agriculture, causing US$32 billion in crop production losses worldwide. In Michigan, highly troublesome and widespread weeds include waterhemp, Palmer amaranth, common ragweed, and horseweed, with accessions that are resistant to glyphosate (Group 9) and ALS-inhibitors (Group 2), major herbicide sites of action utilized in soybean and corn cropping systems. Molecular assays for rapid resistance diagnostics to confirm the in-field status of herbicide resistance can assist with more effective, timely, and proactive management. In this research, we developed and tested PCR-based assays to identify target site resistance mechanisms to both herbicide groups through Sanger sequencing and EPSPS copy number variation. Nine different SNPs were identified in five ALS positions known to confer herbicide resistance among all species surveyed. Pro197Ser was the most frequent in horseweed and common ragweed accessions, whereas Trp574Leu was the predominant mutation in Palmer amaranth and waterhemp. Four horseweed accessions contained the Pro106Ser mutation in the EPSPS gene, which confers resistance to glyphosate. Additionally, waterhemp and Palmer amaranth had 2–7 and 20–160 copies of EPSPS, respectively. The assays were validated by comparing genotyping of several field-collected accessions of unknown resistance status with known resistant and susceptible accessions. The efficacy of genotyping assays was >98% and required only two days, confirming that molecular assays are a robust tool for rapid resistance diagnostics. These assays can help growers evaluate herbicide resistance status in weed populations within the same growing season, allowing them to adopt effective management practices.
Title: The potato vine crusher: a new tool for harvest weed seed control
Dr. Andrew McKenzie-Gopsill is a research scientist in weed science with Agriculture and Agri-Food Canada at the Charlottetown Research and Development Centre in Prince Edward Island, Canada. With an emphasis on cultural practices, his lab studies ecological weed management and limiting the impact of weeds on crop productivity. His lab’s main interests are on development of novel weed management tactics, cover crops, and weed ecology of the diverse cropping systems in Atlantic Canada.
Abstract: Harvest weed seed control (HWSC) is highly effective for the control of a variety of weed species in North American cropping systems yet previous devices have been limited to tow behind and integrated combine systems. The potato vine crusher (PVC) is a harvester-mounted set of rollers originally designed for crushing and control of Ostrinia nubilalis (Hübner) larvae during potato (Solanum tuberosum L.) harvest. To evaluate the potential of the PVC for HWSC, we conducted stationary testing of spring tension and roller speed settings to maximize devitalization of lambsquarters (Chenopodium album L.), the most problematic weed species in Canadian potato production. In addition, we evaluated the efficacy of the PVC for the devitalization of several weed species under controlled conditions and during a simulated harvest. Increasing PVC spring tension reduced the devitalization of lambsquarters seed, whereas roller speed had minimal effect. In contrast, maximized spring tension and minimized roller speed reduced lambsquarters emergence (53%) in soil. High levels of seed devitalization (65%–94%) were observed for all species under controlled conditions. During simulated harvest, control of large weed seeds (50%–63%) was observed, whereas smaller seeds were not impacted, signifying the importance of seed size for PVC efficacy. These studies demonstrate the PVC as a promising new tool for HWSC in Canadian potato production systems.
Title: Palmer amaranth (Amaranthus palmeri S. Wats.) and waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer) biovigilance in Canadian Agro-ecosystems
Dr. Shaun M. Sharpe is a Research Scientist with Agriculture and Agri-Food Canada at the Saskatoon Research and Development Centre in Saskatoon, SK. Dr. Sharpe works primarily on high priority herbicide resistant weeds in annual agronomic systems such as kochia and wild oat. Dr. Sharpe’s research involves herbicide resistance prevention and mitigation, integrated pest management, and developing alternative control techniques. Dr. Sharpe has authored or co-authored 56 peer-reviewed research or extension articles and currently serves as the Governance Director for the Canadian Weed Science Society.
Abstract: Canadian farming sustainability is threatened by the development of herbicide-resistant weeds. Managing herbicide-resistant weeds increases production inputs and costs while increasing pesticide off-target and environmental exposure. Invasive pigweeds such as Palmer amaranth (Amaranthus palmeri S. Wats.) and waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer) are particularly concerning due to their history of invasion, herbicide resistance evolution, and spread into farmers fields. A biovigilance approach is undertaken to initiate an awareness campaign regarding the historic invasion and spread of pigweeds in the USA highlighting their identification, hybridization, and know resistance status. A total of fourteen species of Amaranthus are found in Canada, of which nine possess herbicide-resistant biotypes. Hybridization between Canadian Amaranthus species with each other Palmer amaranth were noted in forty five combinations. Successful mitigation will depend on species identification and current herbicide resistance status for chemical interventions. Palmer amaranth introductions in the northern USA were noted in both animal and plant systems, contaminating grain, screenings, and equipment. Regional awareness campaigns are important to support Canadian farmers in identification and quick mitigation of invasive pigweed as they move into new farmland.