Impact of Climate Change Factors on Weeds and Herbicide Efficacy

Rising carbon dioxide (CO2) concentrations and associated changes in global temperature and precipitation are major concerns for future weed management and crop production. This review focuses on the impacts of climate change factors on the growth of weeds and the potential variations in the efficacy of herbicides under changing climate conditions. Weeds are likely to show greater resilience and better adaptation to changes in CO2 concentrations and rising temperature in competition with crops due to their diverse gene pool and greater physiological plasticity. Weeds with C3 and C4 photosynthetic pathways may exhibit differential responses to higher CO2 levels and temperatures, which can affect the dynamics of crop–weed competition. In addition to its positive impact on weed growth, climate change factors could influence the efficacy of many herbicides, making weed management a major challenge for sustainable crop production. To enhance our understanding of the impact of climate change factors on herbicide efficacy, it is important to evaluate the effects of environmental conditions on various herbicide modes of action. Environmental factors such as CO2, light, temperature, relative humidity, and soil moisture differentially affect the uptake, translocation, and activity of different herbicide chemistries. Furthermore, interactions among these environmental factors may have unpredictable effects on herbicide activity. Existing literature suggests that climate change factors impacts vary not only within herbicide modes of action but also among herbicides belonging to same mode of action, so making generalized assumptions for each mode of action is difficult. Extensive research on the impact of climate change factors and their interactions on all commonly used herbicides is necessary to understand the implications for weed management in future climate scenarios.