Agricultural intensification and climate change have increased the threat from weeds

Abstract

Weeds represent a significant threat to crop yields and global food security. We analysed data on weed competition from the world's longest running agricultural experiment to ask whether potential yield losses from weeds have increased in response to management and environmental change since the advent of the Green Revolution in the 1960s. On plots where inorganic nitrogen fertiliser has been applied, potential yield losses from weeds have consistently increased since 1969. This was explained by a warming climate, measured as air temperature averaged over the growing season for the weeds, and a shift towards shorter crop cultivars. Weeds also reduced yield proportionally more on plots with higher rates of nitrogen which had higher yields when weeds were controlled; the relative benefit of herbicides was, therefore, proportional to potential crop yield. Reducing yield losses from weed competition is increasingly challenging because of the evolution of herbicide resistance. Our results demonstrate that weeds now represent a greater inherent threat to crop production than before the advent of herbicides and integrated, sustainable solutions to weed management are urgently needed to protect the high yield potential of modern crop genotypes.

Potential wheat yield loss due to weeds in the United States and Canada

“…However, these estimates do align with reported by Oerke (2006) of a potential yield loss of 18% to 29%. Greater yield loss due to weeds in our analysis compared with previous estimates corroborates findings of the Broadbalk experiment in England, where yield loss is greater now than before herbicides were introduced (Storkey et al 2021). The trend of increasing losses is attributed to a warming climate and shorter wheat cultivars (Storkey et al 2021).…”

“…Greater yield loss due to weeds in our analysis compared with previous estimates corroborates findings of the Broadbalk experiment in England, where yield loss is greater now than before herbicides were introduced (Storkey et al 2021). The trend of increasing losses is attributed to a warming climate and shorter wheat cultivars (Storkey et al 2021). Potential yield loss is in contrast to realized or actual yield loss.…”

“…Overall crop productivity is lowest in the wheat-fallow agroecological class, and spring wheat is viewed as a weed management rotation with little economic return in that agroecological class (Schillinger and Young 2004). Under future climate change scenarios, the winter wheat-fallow agroecological class is anticipated to grow in area (Karimi et al 2017;Storkey et al 2021), potentially increasing the yield loss potential for the region. Yield loss in spring wheat in the wheat-fallow agroecological class was lowest in the region, but it is also the least productive rotation unless practiced By weighted average based on production, weeds cause a potential 23.5% yield loss in winter wheat across the United States and Canada and 19.5% yield loss in U.S. and Canadian spring wheat when using BMPs but no herbicidal weed control (Table 5).…”

“…As herbicide resistance increases, weed control suffers, potentially causing further reduced yields. Indeed, wheat yield loss in the long running Broadbalk Experiment in England is now greater than it was before herbicides were introduced (Storkey et al 2021).…”

From sea salt to glyphosate salt: a history of herbicide use in France

“…For certain synthetic molecules such as glyphosate, the question seems to be clear-cut (at least in France), but nothing is clearly explained yet for the other synthetic ASs. The effects of climate change (Ziska, 2020;Storkey et al, 2021) on the dynamics of weed communities or on the development of new species (Chadha et al, 2020) will also certainly influence policy-making. Will it be possible to determine weed species, crops or cropping systems for which the highly regulated use of synthetic herbicides will still be possible for agronomic, health or economic reasons?…”