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The discipline of weed science is at a critical juncture. Decades of efficient chemical weed control have led to a rise in the number of herbicide-resistant weed populations, with few new herbicides with unique modes of action to counter this trend and often no economical alternatives to herbicides in large-acreage crops. At the same time, the world population is swelling, necessitating increased food production to feed an anticipated 9 billion people by the year 2050. Here, we consider these challenges along with emerging trends in technology and innovation that offer hope of providing sustainable weed management into the future. The emergence of natural product leads in discovery of new herbicides and biopesticides suggests that new modes of action can be discovered, while genetic engineering provides additional options for manipulating herbicide selectivity and creating entirely novel approaches to weed management. Advances in understanding plant pathogen interactions will contribute to developing new biological control agents, and insights into plant–plant interactions suggest that crops can be improved by manipulating their response to competition. Revolutions in computing power and automation have led to a nascent industry built on using machine vision and global positioning system information to distinguish weeds from crops and deliver precision weed control. These technologies open multiple possibilities for efficient weed management, whether through chemical or mechanical mechanisms. Information is also needed by growers to make good decisions, and will be delivered with unprecedented efficiency and specificity, potentially revolutionizing aspects of extension work. We consider that meeting the weed management needs of agriculture by 2050 and beyond is a challenge that requires commitment by funding agencies, researchers, and students to translate new technologies into durable weed management solutions. Integrating old and new weed management technologies into more diverse weed management systems based on a better understanding of weed biology and ecology can provide integrated weed management and resistance management strategies that will be more sustainable than the technologies that are now failing.

Trifludimoxazin is a protoporphyrinogen oxidase (PPO)-inhibiting herbicide currently under development for preplant burndown and soil-residual weed control in soybean [Glycine max (L.) Merr.] and other crops. Greenhouse dose–response experiments with foliar applications of trifludimoxazin, fomesafen, and saflufenacil were conducted on susceptible and PPO inhibitor–resistant (PPO-R) waterhemp [Amaranthus tuberculatus (Moq.) Sauer] and Palmer amaranth (Amaranthus palmeri S. Watson) biotypes. These PPO-R biotypes contained the PPO2 target-site (TS) mutations ΔG210 (A. tuberculatus and A. palmeri), R128G (A. tuberculatus), and V361A (A. palmeri). The resistant/susceptible (R/S) ratios for fomesafen and saflufenacil ranged from 2.0 to 9.2 across all PPO-R biotypes. In contrast, the response of known PPO inhibitor–susceptible and PPO-R biotypes to trifludimoxazin did not differ within each Amaranthus species. In 2017 and 2018, experiments at the Meigs and Davis Purdue Agriculture Centers were conducted in fields with native A. tuberculatus populations composed of 3% and 30% PPO-R plants (ΔG210 mutation), respectively. At Meigs in 2018, A. tuberculatus control following foliar applications of fomesafen, lactofen, saflufenacil, and trifludimoxazin was greater than 95%. When averaged across the other 3 site-years, applications of 25 g ai ha−1 trifludimoxazin resulted in 95% control of A. tuberculatus at 28 DAA, while applications of fomesafen (343 g ai ha−1), lactofen (219 g ai ha−1), or saflufenacil (25.0 or 50 g ai ha−1), resulted in 80% to 88% control. Thus, at these relative application rates, the foliar efficacy of trifludimoxazin was comparable or greater on A. tuberculatus when compared with other commercial PPO inhibitors, even in populations where low frequencies of PPO-R plants exist. The lack of cross-resistance for common PPO2 TS mutations to trifludimoxazin and the level of foliar field efficacy observed on populations containing PPO-R individuals suggest that trifludimoxazin may be a valuable herbicide in an integrated approach for managing herbicide-resistant Amaranthus weeds.

Florpyrauxifen-benzyl is a new synthetic auxin herbicide labeled in rice with a broad spectrum of control, typically more potent on broadleaf weeds. It has garnered some interest as a potential broadleaf weed control option for use in corn at low rates. Field experiments were conducted in Fayetteville, Arkansas, from 2019 through 2021 to examine the response of corn to postemergence applications of florpyrauxifen-benzyl at three rates (7.5, 15, and 30 g ae ha -1 ), as well as mixtures of the herbicide with atrazine (at half or full rate), mesotrione, or a combination of atrazine (at half rate) and mesotrione. Injury and yield response varied among years, possibly attributed to temperature and solar radiation variations following treatment application. Three weeks after application (WAA), stand-alone florpyrauxifen-benzyl or mixtures caused incrementally greater injury with increasing rates (5% to 76% injury). The levels of early injury were largely sustained at 7 WAA, with a few instances of recovery, particularly with a mixture of florpyrauxifen-benzyl at 7.5 g ae ha -1 with the full rate of atrazine. Corn yield loss generally surpassed the respective injury levels. The yield loss was overall the least in 2020 (8 to 46%) and most severe in 2021 (26 to 93%), largely depending on florpyrauxifen-benzyl rates. Averaged across years, the full rate of atrazine mixed with florpyrauxifen-benzyl at 7.5 g ae ha -1 caused less yield loss (12%) compared to the stand-alone application (28% yield loss). These results suggest that using florpyrauxifen-benzyl in corn, even at low rates and/or in a mixture with atrazine/mesotrione, can cause immediate and sustained injury, often leading to greater than 10% yield reduction. Further research could explore in-crop, in-chemistry, or in-application technology opportunities for mitigating this inadequate safety to render this novel tool a viable option for use in corn.

BackgroundWeed control is essential in modern agriculture, though it has become more difficult with the emergence of resistance to most current herbicides and the slow registration process for new compounds.ObjectiveIdentify herbicide candidates using an innovative artificial intelligence algorithm that takes into effect biological parameters with the goal of reducing research and development time of new herbicides.ResultsWe describe the discovery of 4-chloro-2-pentenamides as novel inhibitors of protoporphyrinogen oxidase (PPO), a known herbicide target site, by the Agrematch AI. Their herbicidal activity was evaluated in greenhouse assays, with the highest performing compound (AGR001) showing good activity pre-emergent at 150 g ha-1 and post emergent at 50 g ha-1 on the troublesome weed Palmer amaranth (Amaranthus palmeri). A lack of activity is reported on PPO resistant Palmer amaranth carrying the glycine 210 deletion (ΔG210) mutation.ConclusionsThe mode of action of 4-chloro-2-pentenamides was confirmed by the herbicide-dependent accumulation of protoporphyrin IX, subsequent light-dependent loss of membrane integrity, and direct in vitro inhibition of PPO. Modeling of these inhibitors’ docking in the active site of PPO shows that their flexible side chains can accommodate several binding poses in the catalytic domain.

Water pollution and fossil fuels are major issues in the context of climate change. Photocatalysis research is rising to develop green technologies for the remediation of pollutants and for energy production. Photocatalysis converts the light energy as photons into chemical energy using semiconducting materials. Different methods are utilised to synthesise these photocatalytic materials. Metal and coupled metal frameworks are applied for the production of photocatalytic materials. Here we review the synthesis and applications of photocatalysts for environmental decontamination and for production of biodiesel, methanol and hydrogen. Pollutants include dyes, pesticides, herbicides, phenols and antibiotics.

1. Invasive plants can reduce biodiversity, alter ecosystem functions and have considerable economic impacts. Invasive plant control is therefore the focus of restoration research in invader-dominated ecosystems. Increasing the success of restoration practice requires analysis and synthesis of research findings and assessment of how experiments can be improved. 2. In a systematic review and meta-analysis of invasive plant control research papers, we asked: (i) what control efforts have been most successful; and (ii) what invasive plant control research best translates into successful restoration application? 3. The literature evaluated typically described experiments that were limited in scope. Most plot sizes were small (< 1 m²), time frames were brief (51% evaluated control for one growing season or less) and few species and ecosystems (predominantly grasslands) were studied throughout much of the literature. The scale at which most experiments were conducted potentially limits relevance to the large scales at which restorations typically occur. 4. Most studies focused on invasive species removal and lacked an evaluation of native revegetation following removal. Few studies (33%) included active revegetation even though native species propagule limitation was common. Restoration success was frequently complicated by re-invasion or establishment of a novel invader. 5. Few studies (29%) evaluated the costs of invasive species control. Additionally, control sometimes had undesirable effects, including negative impacts to native species. 6. Synthesis and applications. Despite a sizeable literature on invasive plant control experiments, many large-scale invasive plant management efforts have had only moderate restoration success. We identified several limitations to successful invasive species control including: minimal focus on revegetation with natives after invasive removal, limited spatial and temporal scope of invasive plant control research, and incomplete evaluation of costs and benefits associated with invasive species management actions. We suggest that information needed to inform invasive plant management can be better provided if researchers specifically address these limitations. Many limitations can be addressed by involving managers in research, particularly through adaptive management.

The potential for gene flow between cultivated species and their weedy relatives poses agronomic and environmental concerns, particularly when there are opportunities for the transfer of adaptive or agronomic traits such as herbicide resistance into the weedy forms. Grain sorghum (Sorghum bicolor) is an important crop capable of interspecific hybridization with its weedy relative johnsongrass (Sorghum halepense). Previous findings have shown that triploid progenies resulting from S. bicolor × S. halepense crosses typically collapse with only a few developing into mature seeds, whereas tetraploids often fully develop. The objective of this experiment was to determine the impact of S. bicolor genotype and pollen competition on the frequency of hybridization between S. bicolor and S. halepense. A total of 12 different cytoplasmic male sterile S. bicolor genotypes were compared with their respective male fertile lines across 2 years, to assess the frequency of hybridization and seed set when S. halepense served as the pollinator parent. Results indicate significant differences in the frequency of interspecific hybridization among the S. bicolor genotypes, and pollen fertility in S. bicolor reduced the rate of this interspecific hybridization by up to two orders of magnitude. Further, hybridization rates greatly varied across the two study environments. Results are helpful for developing appropriate gene flow mitigation strategies and indicate that gene flow could be reduced by the selection of appropriate seed parents for sorghum hybrids.

Pesticides, widely used in modern agriculture, could potentially cause environmental pollution and affect human lives. Hence, the development of a highly sensitive sensing element to detect pesticide residues is crucial for food safety and ecosystem protection. Optical methods based on fluorescence properties provide an ideal approach for screening and quantification of these compounds in different medias including water, plant, and nutritional products. The development of fluorescence emitting carbon dot-based sensors for monitoring pesticides has attracted great attention in recent years. In comparison to other fluorophores, carbon dots have more promising optical features, higher quantum yields and better biocompatibility. This article aims to present a novel fluorescent sensing method of diazinon, glyphosate, and amicarbazone using plant-based carbon dots. A comprehensive characterization of carbon dots obtained from cauliflower was performed by methods including UV-visible, FTIR spectroscopy, fluorometry, AFM, DLS, and zeta sizer. Following this step, carbon dots were used to detect pesticides. The fluorescence quenching property of carbon dots has been utilized to identify detection limit of 0.25, 0.5, and 2 ng ml-1 for diazinon, amicarbazone, and glyphosate, respectively. Also, real sample study revealed that the detection of pesticides accompanied by our developed nano-sensor is repeatable and accurate. According to carbon dots specificity determination, the prepared nano sensor does not have the potential to identify \"bromacil\" and \"dialen super\" pesticides but the other three mentioned pesticides are detectable. The results confirm that synthesized green carbon dots are well qualified for application in food safety and environmental monitoring.

Pesticides and fertilizers are widely used to enhance agriculture yields, although the fraction of the pesticides applied in the field that reaches the targets is less than 0.1%. Such indiscriminate use of chemical pesticides is disadvantageous due to the cost implications and increasing human health and environmental concerns. In recent years, the utilization of nanotechnology to create novel formulations has shown great potential for diminishing the indiscriminate use of pesticides and providing environmentally safer alternatives. Smart nano-based pesticides are designed to efficiently delivery sufficient amounts of active ingredients in response to biotic and/or abiotic stressors that act as triggers, employing targeted and controlled release mechanisms. This review discusses the current status of stimuli-responsive release systems with potential to be used in agriculture, highlighting the challenges and drawbacks that need to be overcome in order to accelerate the global commercialization of smart nanopesticides.

Invasive plants have a multitude of impacts on plant communities through their direct and indirect effects on soil chemistry and ecosystem function. For example, plants modify the soil environment through root exudates that affect soil structure, and mobilize and/or chelate nutrients. The long-term impact of litter and root exudates can modify soil nutrient pools, and there is evidence that invasive plant species may alter nutrient cycles differently from native species. The effects of plants on ecosystem biogeochemistry may be caused by differences in leaf tissue nutrient stoichiometry or secondary metabolites, although evidence for the importance of allelochemicals in driving these processes is lacking. Some invasive species may gain a competitive advantage through the release of compounds or combinations of compounds that are unique to the invaded community—the “novel weapons hypothesis.” Invasive plants also can exert profound impact on plant communities indirectly through the herbicides used to control them. Glyphosate, the most widely used herbicide in the world, often is used to help control invasive weeds, and generally is considered to have minimal environmental impacts. Most studies show little to no effect of glyphosate and other herbicides on soil microbial communities. However, herbicide applications can reduce or promote rhizobium nodulation and mycorrhiza formation. Herbicide drift can affect the growth of non-target plants, and glyphosate and other herbicides can impact significantly the secondary chemistry of plants at sublethal doses. In summary, the literature indicates that invasive species can alter the biogeochemistry of ecosystems, that secondary metabolites released by invasive species may play important roles in soil chemistry as well as plant-plant and plant-microbe interactions, and that the herbicides used to control invasive species can impact plant chemistry and ecosystems in ways that have yet to be fully explored.