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

Abstract

BACKGROUND By 2050, weather is expected to become more variable with a shift towards higher temperatures and more erratic rainfall throughout the U.S. Corn Belt. The effects of this predicted weather change on pre‐emergence (PRE) herbicide efficacy have been inadequately explored. Using an extensive database, spanning 252 unique weather environments, the efficacy of atrazine, acetochlor, S‐metolachlor, and mesotrione, applied PRE alone and in combinations, was modeled on common weed species in corn (Zea mays L.). RESULTS Adequate rainfall to dissolve the herbicide into soil water solution so that it could be absorbed by developing weed seedlings within the first 15 days after PRE application was essential for effective weed control. Across three annual weed species, the probability of effective control increased as rainfall increased and was maximized when rainfall was 10 cm or more. When rainfall was less than 10 cm, increasing soil temperatures had either a positive or negative effect on the probability of effective control, depending on the herbicide(s) and weed species. Herbicide combinations required less rainfall to maximize the probability of effective control and had higher odds of successfully controlling weeds compared with the herbicides applied individually. CONCLUSIONS Results of this study highlight the importance of rainfall following PRE herbicide application. As rainfall becomes more variable in future, the efficacy of common PRE herbicides will likely decline. However, utilizing combinations of PRE herbicides along with additional cultural, mechanical, biological, and chemical weed control methods will create a more sustainable integrated weed management system and help U.S. corn production adapt to more extreme weather. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of the Time of Herbicide Application and the Properties of the Spray Solution on the Efficacy of Weed Control in Maize (Zea mays L.) Cultivation

“…These plant protection products made it possible to protect maize against competition from weeds from the very beginning of its development [68,69]. However, it should be remembered that the condition for achieving the appropriate efficacy of this type of treatment is adequate soil moisture [70].…”

Above- and belowground linkages during extreme moisture excess: leveraging knowledge from natural ecosystems to better understand implications for row-crop agroecosystems

“…Pre-emergent herbicides are effective at controlling many agriculturally relevant species, and often require some precipitation for activation (1–2 cm precipitation). Successful weed control in corn was determined to need 5–10 cm precipitation within 15 d of application to effectively incorporate herbicides and facilitate ­uptake by weeds ( Landau et al , 2021 ). However, rainfall totals greater than those assessed by Landau et al (2021) may result in challenges with retaining applied herbicides ( Ramesh et al , 2017 ) or applying them at all (field conditions too wet to facilitate a timely application).…”

Diminishing weed control exacerbates maize yield loss to adverse weather

“…For instance, weed control failure is high with inadequate precipitation shortly after application of soil-applied herbicides (Landau et al, 2021). High temperatures hasten the growth rate of important weed species and reduce the amount of time that foliar-applied herbicides provide control (Guo & Al-Khatib, 2003).…”

“…How to cite this article: Landau, C. A., Hager, A. G., & Williams, M. M. II (2021). Diminishing weed control exacerbates maize yield loss to adverse weather.…”

“…In 2018, 97% of all US maize hectares received one or more herbicide applications (USDA-NASS, 2021). Between 2008 and 2012, global producers spent roughly $26 billion annually on herbicides (Atwood & Paisley-Jones, 2017).Herbicide efficacy, determined empirically using a "weed control" rating system during the growing season, ranging from 0% (no weed control) to 100% (complete weed control), varies by product, application rate and timing, weed species, and environmental conditions.For instance, weed control failure is high with inadequate precipitation shortly after application of soil-applied herbicides (Landau et al, 2021). High temperatures hasten the growth rate of important weed species and reduce the amount of time that foliar-applied herbicides provide control (Guo & Al-Khatib, 2003).…”