Dr. Charles M. Geddes, Ph.D., P.Ag.

Image Charles M. Geddes
Research Scientist - Weed Ecology and Cropping Systems
  • Herbicide-resistant plants
  • Weed ecology, biology and management
  • Integrated weed management
  • Weed seedbank dynamics
  • Crop/weed interference
  • Long-term agroecosystem experiments

Current research and/or projects

16. Principal Investigator. Title "Old plots, new hypotheses: Toward a revitalized AAFC long-term agroecosystem experiment (LTAE) network." AAFC Management Solicited Initiative. 2019-2022.

15. Principal Investigator. Title "Development of an integrated weed management (IWM) package to mitigate and manage glyphosate-resistant weeds in soybean." WGRF, MPSG, CAP Ag Action MB Program. 2019-2024.

14. Principal Investigator. Title "Management of glyphosate-resistant kochia in western Canadian cropping systems." ICA Cluster - CAP, WGRF, MPSG, MWBGA, AAFC. 2018-2023.

13. Principal Investigator. Title "Weed seed-suppressive soils: Managing herbicide-resistant weed populations at the source." AAFC A-base. 2018-2021.

12. Co-Investigator. Title "Beneficial insects in Prairie crops: quantifying the value and vulnerability of biological pest control." AAF, AWC, AB, SWDC. 2019-2022.

11. Co-Investigator. Title "Development of improved protocols for the culture of arbuscular mycorrhizal fungi with high symbiotic potential according to the analyses of soil microbiome." AAFC A-base. 2018-2021.

10. Co-Investigator. Title "Delivery of an innovative winter wheat package to achieve sustainable wheat production in the Canadian Prairies." CNW Cluster - CAP. 2018-2023.

9. Co-Investigator. Title "Glyphosate-resistant kochia/Russian thistle surveys." WGRF. 2018-2023.

8. Co-Investigator. Title "Identifying agronomic and environmental benefits and drawbacks of diverse crops in cereal/canola/pulse crop rotations on the semi-arid Canadian Prairies. DFC Cluster - CAP. 2018-2023.

7. Co-Investigator. Title "Improving the management of sclerotinia stem rot of canola using fungicides and better risk assessment tools. CAR Cluster - CAP. 2018-2023.

6. Co-Investigator. Increasing the suitability of the Holos model for life cycle analysis through production cycle inputs, collaborative/open source development, and the development of representative farm systems. AAFC A-base. 2019-2022.

5. Co-Investigator. Integrating multiple beneficial management practices (BMPs) in an organic cropping system: Soil health, weed and insect interactions. AAFC A-base. 2018-2021.

4. Co-Investigator. Title "Long-term sustainable canola production - All phases rotations. WGRF, ACPC. 2017-2020.

3. Co-Investigator. Title "Manipulating agronomic factors for optimum canola harvest timing, productivity and crop sequencing." CAR Cluster - CAP. 2018-2023.

2. Co-Investigator. Title "Mitigating herbicide resistance - Investigating novel integrated weed maangement systems." WGRF, ACPC, ABC, SWDC. 2016-2021.

1. Co-Investigator. Title "The right balance: Management strategies for plugging organic soil health constraints and moving forward." OS Cluster III - CAP. 2018-2023.


Education and awards

Doctor of Philosophy (Plant Science), University of Manitoba, 2018

Bachelor of Science (Agroecology), University of Manitoba, 2012

Key publications

  1. Prabahar Ravichandran, Keshav D. Singh, Charles M. Geddes, Manoj Natarajan, Austin Jaster, and Hongquan Wang, "Proximal Hyperspectral Imaging to Classify Herbicide-Resistant and -Susceptible Kochia (Bassia Scoparia)", 11th International Conference of Agro-Geoinformatics, Wuhan, China, July 2023

    2023 - View publication details

  2. Prabahar Ravichandran, Keshav D. Singh, Charles M. Geddes, Breanne Tidemann, Eric Johnson, Steve Shirtliffe, Thomas K. Turkington, and Manoj Natarajan, "Utilizing Hyperspectral Imaging Technology to Characterize Herbicide Phytotoxicity in Oat and Mustard", 11th International Conference of Agro-Geoinformatics, Wuhan, China, July 2023

    2023 - View publication details

  3. Tidemann BD, Sharpe S, Geddes CM (2023) Curious and Concerning False Cleavers (Galium spurium) response to Quinclorac. Western Society of Weed Science Annual Meeting, Boise, Idaho. Feb 27 - March 2, 2023. Poster # 36

    2023 - View publication details

  4. Norris, C.E., Gorzelak, M., Arcand, M., Bruhjell, D., Carlyle, C.N., Dyck, M., Ellert, B., Entz, M., Geddes, C.M., Hao, X., Janovicek, K., Larney, F., May, W., Luce, M.S., Van Eerd, L.L., Zhang, T., Beck, R., Cowen, T., Liptzin, D., Morgan, C.L.S. (2023). The story of long-term research sites and soil health in Canadian agriculture. Canadian Journal of Soil Science, [online] 103(1), 164-190. http://dx.doi.org/10.1139/cjss-2021-0174

    2023 - View publication details

  5. Sharpe SM, Leeson J, Geddes C, Beckie H, Willenborg C (2022) Survey of Glyphosate- and Dicamba-Resistant Kochia in Saskatchewan. Annual meeting of the Canadian Weed Science Society in Halifax, NS. November 14, 2022.

    2022 - View publication details

  6. Geddes, C.M. 2022. FMC Pre-School presents: Let's Talk Kochia with Dr. Charles Geddes. FMC Pre-School AGRC' 103. 2022-02-15. (Oral Presentation).

    2022 - View publication details

  7. Geddes, C.M. 2022. Herbicide-resistant weeds. Richardson Pioneer Growing For Success Conference. 2022-02-03. (Oral Presentation).

    2022 - View publication details

  8. Geddes, C.M. 2022. Weeds & herbicide resistance: What was observed in 2021? 2022 Alberta Agronomy Update. 2022-01-12. (Oral Presentation).

    2022 - View publication details

  9. Geddes, C.M. 2022. Fundamentals of weed control. 2022 Alberta Agronomy Update, Back to Basics Session. 2022-01-05.

    2022 - View publication details

  10. Geddes, C.M., Gulden, R.H., Jones, T., Leeson, J.Y., Pittman, M.M., Sharpe, S.M., Shirriff, S.W., Beckie, H.J. (2022). Baseline survey of herbicide resistance in Russian thistle (Salsola tragus L.) finds no resistance in Manitoba. Canadian Journal of Plant Science, [online] 102(1), 246-249. http://dx.doi.org/10.1139/cjps-2020-0260

    2022 - View publication details

  11. Geddes, C.M. 2021. Herbicide Resistance – Act now before it’s too late. 2021 Manitoba Agronomists Conference. Dec 14-15, 2021. [Virtual]. (Oral Presentation).

    2021 - View publication details

  12. Geddes, C.M. 2021. Prairie herbicide-resistant weed research update. 2021 Pulse Agronomy Workshop. 2021-11-24.

    2021 - View publication details

  13. Geddes, C.M. Herbicide resistance in Alberta. Saddle Hills County Webinar Series. 2021-11-17. (Oral Presentation).

    2021 - View publication details

  14. Geddes, C.M. 2021. Weed management in Alberta cropping systems. Virtual Guest Lecture. PLSC 499 Cropping Systems Course. University of Alberta, Edmonton, AB, CA. November 16, 2021. Instructor: M. Thilakarathna.

    2021 - View publication details

  15. Nair, J., Lima, P.M.T., Abdalla, A.L., Molnar, L.J., Wang, Y., McAllister, T., and Geddes, C.M. 2021. Kochia (Bassia scoparia) harvest date impacts nutrient composition, in vitro degradability, and feed value more than pre-harvest herbicide treatment or herbicide resistance traits. 2021 American Society of Agronomy (ASA) – Crop Science Society of America (CSSA) – Soil Science Society of America (SSSA) International Annual Meeting Nov 07-10, 2021. Salt Lake City, UT. (Poster Presentation).

    2021 - View publication details

  16. Tiffen, S., and Geddes, C.M. 2021. White cockle [Silene latifolia Poir.]. Weed Wisdom. October 2021. Farming Smarter Monthly E-newsletter. 23 Views.

    2021 - View publication details

  17. Makela, K., et al. (2021). Biovigilance: A Modern Approach to Plant Pest Management (Vision Statement), Agriculture and Agri-Food Canada, Science and Technology Branch: 29 pp.

    2021 - View publication details

  18. Geddes, C.M., Tidemann, B.D., and Sharpe, S.M. 2021. AAFC Herbicide resistance research update. Saskatchewan Crop Diagnostic School. 2021-07-28.

    2021 - View publication details

  19. Geddes, C.M. 2021. Kochia loves this drought! Weed Wisdom. July 2021. Farming Smarter Monthly E-newsletter.

    2021 - View publication details

  20. Geddes, C.M., and Tidemann, B.D. 2021. Wicked weeds of the west and their bioclimatic drivers. Agriculture and Agri-Food Canada, Alberta Science Conversation Seminar Series. 2021-06-23. (Oral presentation).

    2021 - View publication details

Research facility

5403 1st Avenue South
Lethbridge, AB T1J 4B1


Alberta Institute of Agrologists (member)

American Society of Agronomy (member)

Crop Science Society of America (member)

Canadian Society of Agronomy (member)

Canadian Weed Science Society (member)

Weed Science Society of America (member)