Future efficacy of pre-emergence herbicides in corn (Zea mays) is threatened by more variable weather

Authors: LANDAU, CHRISTOPHER - University Of Illinois; HAGER, AARON - University Of Illinois; TRANEL, PATRICK - University Of Illinois; DAVIS, ADAM - University Of Illinois; MARTIN, NICHOLAS - University Of Illinois; Williams, Martin

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2021
Publication Date: 2/20/2021
Citation: Landau, C., Hager, A., Tranel, P., Davis, A., Martin, N., Williams II, M.M. 2021. Future efficacy of pre-emergence herbicides in corn (Zea mays) is threatened by more variable weather. Pest Management Science. 77(6):2683-2689. https://doi.org/10.1002/ps.6309.
DOI: https://doi.org/10.1002/ps.6309

Interpretive Summary: Preemergence herbicides are central to weed management in US corn production; however, the extent to which climate change will affect their effectiveness is unknown. The research used a novel approach to explore the extent to which weather factors, namely rainfall and temperature, affect performance of preemergence herbicides. By mining the data from nearly 2,700 herbicide evaluation trials across 25 years, the authors quantified functional relationships between key weather variables and weed control for some of the most widely used preemergence herbicides. Knowledge gained from the research identifies ways to reduce risk of poor weed control due to inadequate rainfall. The research will impact US corn production by helping create a more durable, integrated weed management system as agriculture adapts to climate change.

Technical Abstract: BACKGROUND: Over the next three decades, weather is predicted to become more variable and shift towards wetter springs and warmer drier summers throughout the US Corn Belt. The effects of this predicted weather change on preemergence (PRE) herbicide efficacy has been inadequately explored. Using a large database of herbicide evaluation trials, we modeled the efficacy of atrazine, acetochlor, S-metolachlor, and mesotrione, used alone and in combinations, on common weed species in corn (Zea mays L.) across a vast range of weather environments. RESULTS: Rainfall within the first 15 days after PRE application was essential for weed control. For each treatment, the probability of control increased as rainfall increased and was maximized when rainfall was = 10 cm. When rainfall was <10 cm, increasing soil temperatures had either a positive or negative effect on the probability of control, depending on the treatment and weed species. Combinations of atrazine, acetochlor, S-metolachlor, and mesotrione required less rainfall to maximize the probability of control and had higher odds of successfully controlling weeds compared to the herbicides individually. CONCLUSIONS: Our findings highlight the importance of rainfall following PRE herbicide application. As rainfall becomes more variable in the future, efficacy of PRE herbicides may be reduced. However, utilizing combinations of PRE herbicides along with additional chemical, cultural, and mechanical control methods will help create a more durable integrated weed management system and help US corn production prepare for future changing weather.