Weather and glufosinate efficacy; a retrospective analysis looking forward to the changing climate

Authors: Landau, Christopher; BRADLEY, KEVIN - University Of Missouri; BURNS, ERIN - Michigan State University; DEWERFF, RYAN - University Of Wisconsin; DOBBELS, ANTHONY - The Ohio State University; ESSMAN, ALYSSA - The Ohio State University; FLESSNER, MICHAEL - Virginia Tech; GAGE, KARLA - Southern Illinois University; HAGER, AARON - University Of Illinois; JHALA, AMIT - University Of Nebraska; JOHNSON, PAUL - South Dakota State University; JOHNSON, WILLIAM - Purdue University; LANCASTER, SARAH - Kansas State University; LINGENFELTER, DWIGHT - Pennsylvania State University; LOUX, MARK - The Ohio State University; MILLER, ERIC - Southern Illinois University; MICHAEL, OWEN - Iowa State University; SARANGI, DEBALIN - University Of Minnesota; SIKKEMA, PETER - University Of Guelph; SPRAGUE, CHRISTY - Michigan State University; VANGESSEL, MARK - University Of Delaware; WERLE, RODRIGO - University Of Wisconsin; YOUNG, BRIAN - Purdue University; Williams, Martin

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2024
Publication Date: 1/8/2025
Citation: Landau, C.A., Bradley, K., Burns, E., Dewerff, R., Dobbels, A., Essman, A., Flessner, M., Gage, K., Hager, A., Jhala, A., Johnson, P., Johnson, W., Lancaster, S., Lingenfelter, D., Loux, M., Miller, E., Michael, O., Sarangi, D., Sikkema, P., Sprague, C., Vangessel, M., Werle, R., Young, B., Williams, M. 2025. Weather and glufosinate efficacy; a retrospective analysis looking forward to the changing climate. Weed Science. https://doi.org/10.1017/wsc.2024.101.
DOI: https://doi.org/10.1017/wsc.2024.101

Interpretive Summary: Over the next century, crop production regions of central North America are expected to experience a greater frequency of extreme weather events. How might climate change affect performance of glufosinate, a postemergence herbicide used in corn, cotton and soybean? We analyzed university-led herbicide trials with glufosinate from across thousands of environments and developed models to predict relationships between weather variability and glufosinate performance. As air temperatures increase and precipitation becomes more variable for most of North America, the risk of unacceptable weed control with glufosinate is likely to increase.

Technical Abstract: Foliar-applied postemergence (POST) applications of glufosinate are often applied to glufosinate-resistant crops to provide nonselective weed control without significant crop injury. Rainfall, air temperature, solar radiation, and relative humidity near the time of application has been reported to affect glufosinate efficacy. However, previous research may have not captured the full range of weather variability to which the herbicide may be exposed to prior to or following application. The objective of this research was to quantify the probability of successful weed control (efficacy =85%) with glufosinate applied to several key weed species across a broad range of weather conditions. A database of >10,000 North American herbicide evaluation trials was used in this study. The database was filtered to include treatments with a single POST application of glufosinate applied to waterhemp (Amaranthus tuburculatus (Moq.) J. D. Sauer), morningglory species (Ipomoea spp.), and/or giant foxtail (Setaria faberi Herm.) <15cm in height. Individual random forest models were created for the three species. Low rainfall (=20 mm) over the five days prior to glufosinate application was detrimental to the probability of successful control of waterhemp and giant foxtail. Lower relative humidity (=70%) and solar radiation (=23 MJ m-1 day-1) the day of application reduced the probability of successful weed control in most cases. Additionally, the probability of successful control decreased for all three species when average air temperature over the first five days after application was =25°C. As climate continues to change and become more variable, the risk of unacceptable control of several common species with glufosinate is likely to increase.