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BACKGROUND: A 4‐year experiment evaluated the effects of different integrated weed management (IWM) programs on the evolution of a Echinochloa crus‐galli population resistant to acetolactate synthase (ALS) inhibitors in a maize cropping system. The programs included the continued use of ALS inhibitors, mixing them with alternative herbicides, or without ALS‐inhibitors, in all cases under maize monocrop or a biennial crop rotation. RESULTS: IWM programs that relied solely on non‐ALS‐inhibitors usually achieved high control levels across years (> 90%). Additionally, Trp574Leu‐resistant plants became prevalent (> 90%) in programs only using ALS inhibitors, while in the rest the frequency of susceptible plants did not substantially decrease below 40%. Regarding the other monitored grass weeds, Digitaria sanguinalis and Panicum dichotomiflorum were effectively controlled in programs using ALS‐inhibitors without soybean rotation or in programs without ALS‐inhibitors altogether, excepting the program relying on an 4‐hydroxyphenylpyruvate dioxygenase (HPPD)‐inhibitor under maize monocrop for the latter species (0%). CONCLUSION: At the end of the experiment, the only IWM programs that reduced infestation levels were the one without ALS‐inhibitors under soybean rotation, and the one with standard pre‐emergence treatments. These findings highlight the effectiveness of crop rotation and alternative herbicides both pre‐ or post‐emergence in controlling E. crus‐galli. ALS‐inhibitors, while challenged by resistance in E. crus‐galli, remain valuable tools for managing other grass weed species in maize. It is crucial to adapt IWM strategies for herbicide‐resistant E. crus‐galli and other grass weed populations to mitigate the further evolution of resistance. © 2024 Corteva Agriscience. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Annual ryegrass (Lolium rigidum) is a problematic weed in winter crops and fallows in the southeastern cropping region (SCR) of Australia. This weed has evolved resistance to multiple herbicide groups, globally. In Australia, L. rigidum is more prevalent in the western and southern regions than in SCR. To assess the herbicide resistance status of L. rigidum, the response of five L. rigidum populations (collected from the SCR) to glyphosate, glufosinate, paraquat, haloxyfop-P-ethyl, and clethodim is determined using dose–response curves. Three parametric logistic models are used to determine the herbicide dose required to achieve 50% survival (LD50) and 50% growth reduction (GR50). The LD50 values for 50% survival at 28 days after treatment range from 1702 g a.e. ha−1 to 8225 g a.e. ha−1 for glyphosate, 1637 g a.i. ha−1 to 1828 g a.i. ha−1 for glufosinate, 141 g a.i. ha−1 to 307 g a.i. ha−1 for paraquat, 11 g a.i. ha−1 to 107 g a.i. ha−1 for haloxyfop-P-ethyl, and 17 g a.i. ha−1 to 48 g a.i. ha−1 for clethodim. The resistance factor, based on GR50 value, is highest in the S7 population (2.2 times) for glyphosate, the S11 population (2.3 times) for glufosinate, the S11 population (2.0 time) for paraquat, the S7 population (3.9 times) for haloxyfop-P-ethyl, and the S3 population (3.1 times) for clethodim, compared with the susceptible or less tolerant population. The S11 population is found to be resistant to five tested herbicides, based on resistance factors. Similarly, the S3 population is highly resistant to glyphosate, haloxyfop-P-ethyl, and clethodim compared with the W4 population. These results suggest that L. rigidum populations in the SCR exhibit resistance to multiple herbicide groups at labelled field rates. The findings highlight the necessity of adopting an integrated management approach, including the use of residual herbicides, tank mixing herbicides with different modes of action, and rotating herbicides in conjunction with cultural and mechanical control methods. [ABSTRACT FROM AUTHOR]

Crop productivity is affected by various abiotic and biotic factors. Weeds act as the most serious biological constraint by reducing crop yield, harbouring insect pests and causing serious health hazards. Chemical herbicides were widely employed for weed control in agricultural fields. However, an increase in herbicide-resistant weeds and rising environmental concerns arising from the overuse of synthetic herbicides have led scientists to explore natural ways of managing weeds that are cost-effective and environment-friendly. Ecological control by allelopathic crops has proved to be of great significance in weed management. This review focuses on the problem of herbicide resistance in weeds and the role of allelochemicals in biological weed control. Additionally, the review includes the discussion on the allelopathic potential of various crop plants for weed control which can be exploited for the development of cost-effective and environment-friendly bioherbicide. Further, the discussion on retention and biodegrability of the allelochemicals in rhizosphere along with the studies involving genetic mechanisms underlying allelopathy that will direct the future researches for further progress using allelopathy as a potential tool in sustainable agriculture. [ABSTRACT FROM AUTHOR]

This study was conducted in a newly established (2-year-old) almond orchard to investigate the effects of five different mulching materials (woven and nonwoven fabric, black and white polyethylene, almond shell) and flame treatments applied at two different frequencies (FL20 and FL30) on weed control and almond growth compared with those of conventional herbicide (glyphosate) application and weedy control. Thus, this study included nine different treatments. The impacts of these treatments on weed density and coverage were periodically monitored. Additionally, the biomass of the weeds was measured at the end of the season to evaluate the effects of the treatments. Because the almond orchard was not yet in the economic fruit-bearing stage, the effects of the treatments were examined in terms of parameters that characterize almond growth, such as plant height, trunk diameter, shoot length, and shoot thickness. The chlorophyll content and water potential values of the trees were also determined. The results of this two-season study indicated that synthetic mulches provided the best outcomes in terms of weed control and almond growth. No weed emergence was observed throughout the season in any of the synthetic mulch treatments. Although almond shells used as organic mulch were highly effective for blocking sunlight, they failed to prevent the growth of some vigorously growing perennials such as Cynodon dactylon and Sorghum halepense that emerged from gaps. Flame treatments demonstrated rapid and effective results; however, they were less successful against the aforementioned monocot perennial weeds and required frequent repetition because of the lack of residual effects. Glyphosate, an herbicide that is commonly used in conventional orcharding, was applied five times throughout the experiment and proved effective weed management compared with that of the weedy control. However, considering the increasing herbicide resistance, environmental and health issues, and growing interest in organic almond cultivation, synthetic mulch applications have emerged as good options. Despite the initially higher establishment costs, synthetic mulches effectively controlled weeds and reduced water stress, thereby promoting almond tree growth. [ABSTRACT FROM AUTHOR]

Since the introduction and widespread adoption of chemical herbicides, "weed management" has become almost synonymous with "herbicide management." Over-reliance on herbicides and herbicide-resistant crops has given rise to herbicide resistant weeds. Integrated weed management (IWM) identifies three strategies for weed management— biological-cultural, chemical-technological, mechanical-physical—and recommends combining all three to mitigate herbicide resistance. However, adoption of IWM has stalled, and research to understand the adoption of IWM practices has focused on single stakeholder groups, especially farmers. In contrast, decisions about weed management often occur within a social ecosystem where multiple stakeholder groups co-create knowledge and practices. To more holistically investigate perceptions and decision-making related to herbicide resistant weed management, we conducted 23 in-depth interviews in combination with Q methodology with farmers and public-/private-sector agricultural professionals in the state of Georgia (U.S.). Our investigation focused on the management of an increasingly herbicide resistant weed, Palmer amaranth, which enabled broader conversations about agricultural systems, farmer livelihoods, and sustainability. Factor and thematic analyses allowed us to identify and characterize two distinct typologies: one primarily valued agronomic efficiency and relied upon chemical-technological management practices, while the other valued diversifying weed management strategies as the pathway to agronomic and economic success. Typologies diverged substantially in attitudes toward the three weed management strategies, the role of technology, and systems management generally. These two viewpoints have implications for how we understand underlying stakeholder motivations and choices around weed management strategies, both of which are crucial in promoting and supporting farmer use of diverse, ecologically-sound, weed management strategies. [ABSTRACT FROM AUTHOR]

Dry direct-seeding can get rid of the constraints of high-water demand, and is the simplest and most laborsaving mode in rice (Oryza sativa L.) cultivation. However, weeds are more prone to occur in dry direct-seeding rice fields, coupled with increased herbicide resistance, leading to confusion among growers regarding herbicide selection. In this study, our investigation results revealed total grass quantity reached 458.82 plants m-2. Two round of field experiments were conducted to determine suitable post-emergence herbicides for dry directseeding indica rice. The results showed that among the herbicides safe to indica rice, the efficacy of the combination of pyraquinate (a new 4-hydroxyphenylpyruvate dioxygenase inhibitor, 150.0 g ai ha-1) + florpyrauxifen-benzyl (13.5 g ai ha-1) on Leptochloa chinensis (L.) Nees, Eclipta prostrata (L.) L., Cyperus iria L., Fimbristylis miliacea auct., and total grasses were 89.1%, 97.8%, 97.2%, 90.1%, and 92.8%, respectively; the efficacy of metamifop (120.0 g ai ha-1) + florpyrauxifen-benzyl (18.0 g ai ha-1) and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD (148.5 g ai ha-1) on main weeds also exceeds 85.0%, except for cyhalofop-butyl-resistant L. chinensis. The combination of metamifop + florpyrauxifen-benzyl and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD can be selected for fields where L. chinensis is not resistant to acetyl-CoA carboxylase (ACCase) inhibitors. The combination of pyraquinate + florpyrauxifenbenzyl is the most promising combination to control multiple weeds, even ACCase inhibitors-resistant weeds. This study could also provide references for herbicides selection and management of ACCase inhibitors-resistant L. chinensis in dry direct-seeding indica rice field worldwide. [ABSTRACT FROM AUTHOR]

Herbicide resistance has become a major issue in recent decades. Because diagnostics is still expensive, prediction models are helping to assess risks of resistance evolution. In this paper the influence of weed management on the evolution of resistance of the grass Alopecurus myosuroides Huds to ALSinhibitors is investigated based on field history data from two regions, Hohenlohe in Germany and Champagne in France respectively. Champagne data also comprise information on Lolium spp. Using a random forest method variable importance and performance measures were obtained for a large number of single analyses allowing for a statistical analysis of the four performance measures, type I error, type II error, AUC and accuracy. It could be shown that acceptable predictions can be obtained for training data from Hohenlohe applied to Champagne and vice versa. It turned out that in nearly all analyses false negative classifications are more frequent than false positive classifications. Based on a combined training set of A.myosuroides samples from Hohenlohe and Champagne resistance status of Lolium spp. from the Champagne dataset can be predicted with a good accuracy. This suggest that resistance evolution to ALS-inhibitors of the two grasses are closely related. This work is a first step to set a simple herbicide resistance prediction tool to the users based on field history weed management data. [ABSTRACT FROM AUTHOR]

BACKGROUND: The early detection of herbicide resistance in weeds is a key factor to avoid herbicide waste and improve agriculture sustainability. The present study aimed to develop and validate an allele‐specific loop‐mediated isothermal amplification (AS‐LAMP) assay for the quick on‐site detection of the resistance‐endowing point mutation Trp‐574‐Leu in the acetolactate synthase (ALS) gene in three widely diffused Amaranthus weed species: Amaranthus retroflexus, Amaranthus hybridus and Amaranthus tuberculatus. RESULTS: The AS‐LAMP protocol was developed on wild‐type and ALS‐mutant plants of the three species and revealed that the amplification approach with only the primer set specific for the mutant allele (574‐Leu) was the most promising. The validation and estimation of the AS‐LAMP performance evaluated by comparing the results with those of the molecular marker (cleaved amplified polymorphic sequences) indicated that, although the sensitivity and specificity were relatively high in all species (overall 100 and > 65%, respectively), precision was high for A. hybridus L. and A. retroflexus L. (75 and 79%, respectively), but quite low for A. tuberculatus (Moq.) J. D. Sauer (59%). The LAMP assay was also effective on crude genomic DNA extraction, allowing the quick detection of mutant plants in field situation (on site resistance detection). CONCLUSION: The proposed AS‐LAMP method has proven to be a promising technique for rapid detection of resistance as a result of Trp‐574‐Leu on the two monoecious weedy Amaranthus species but resulted less effective in the genetically variable dioecious species A. tuberculatus. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Amaranthus retroflexus L. (redroot pigweed) is one of the most problematic weeds in maize, sugar beet, vegetables, and soybean crop fields in Europe. Two pigweed amaranth biotypes (R1 and R2) from the Czech Republic resistant to photosystem II (PSII)-inhibiting herbicides were analyzed in this study. This study aimed to identify the genetic mechanisms that underlie the resistance observed in the biotypes. Additionally, we also intended to establish the use of chlorophyll fluorescence measurement as a rapid and reliable method for confirming herbicide resistance in this weed species. Both biotypes analyzed showed high resistance factors in a dose–response study and were thus confirmed to be resistant to PSII-inhibiting herbicides. A sequence analysis of the D1 protein revealed a well-known Ser-Gly substitution at amino acid position 264 in both biotypes. Molecular docking studies, along with the wild-type and mutant D1 protein's secondary structure analyses, revealed that the S264G mutation did not reduce herbicide affinity but instead indirectly affected the interaction between the target protein and the herbicides. The current study identified the S264G mutation as being responsible for conferring herbicide resistance in the pigweed amaranth biotypes. These findings can provide a strong basis for future studies that might use protein structure and mutation-based approaches to gain further insights into the detailed mechanisms of resistance in this weed species. In many individuals from both biotypes, resistance at a very early stage (BBCH10) of plants was demonstrated several hours after the application of the active ingredients by the chlorophyll fluorescence method. The effective PS II quantum yield parameter can be used as a rapid diagnostic tool for distinguishing between sensitive and resistant plants on an individual level. This method can be useful for identifying herbicide-resistant weed biotypes in the field, which can help farmers and weed management practitioners develop more effective weed control tactics. [ABSTRACT FROM AUTHOR]

In recent years, water conservation efforts in rice production have necessitated the use of reduced irrigation input systems such as alternate wetting and drying (AWD) as a substitute to conventional continuous flood‐irrigated systems (FLD), but little is known about the role of AWD in altering outcrossing potentials between cultivated rice and weedy rice (WR). In the United States, rice growers often control WR by cultivating varieties that possess herbicide resistance. However, an ongoing concern with such technology is hybridization or outcrossing between herbicide‐resistant rice cultivars and WR over time. Such outcrossing may result in transferring of herbicide resistance with increased occurrence of herbicide‐resistant WR ecotypes and reduction in the efficacy of herbicide management. This study compared and quantified outcrossing rates between two Clearfield rice varieties (CL142AR and CL261) that are herbicide resistant and two common WR genotypes, strawhull (SH) and blackhull (BH), under FLD and AWD management. Outcrossing was evident in all four genotype combinations (i.e., CL142AR or CL261 cultivated rice and SH or BH weedy rice) in both FLD and AWD; however, outcrossing rates with CL261 averaged about 6.5 times lower than those with CL142AR. Additional analysis revealed that higher outcrossing rates were associated with increased synchrony of flowering times and closer vertical proximity of panicles of WR to CL142AR than with CL261. AWD irrigation reduced outcrossing in SH weedy rice, suggesting that reduced outcrossing of SH weedy rice might be an additional benefit from AWD irrigation management. Core Ideas: Alternate wetting and drying (AWD) irrigation reduced outcrossing in strawhull (SH) weedy rice (WR).Cultivar CL261 had an average 6.5 times lower outcrossing rate than cultivar CL142AR under AWD management.Water conservation irrigation systems could provide an added benefit of reduced outcrossing between rice and WR.New knowledge will help in developing more effective WR control measures in rice production. [ABSTRACT FROM AUTHOR]

BACKGROUND: The widespread use of chemical herbicides and the growing issue of weed resistance pose significant challenges in agriculture. To address these problems, there is a pressing need to develop biological herbicides based on bacterial metabolites. RESULTS: In this study, we investigated the impact of the cell‐free culture filtrate (CFCF) from the ZT isolate, a bacilliform bacterium obtained from diseased wheat seeds, on the germination and seedling growth of various plant species, including wild oat, ryegrass, redroot, wheat, and chickpea. The results revealed that CFCF had a detrimental effect on the fresh and dry weight of stems and roots in most of the studied plants, except chickpeas. The CFCF was further subjected to separation into aqueous and organic phases using chloroform, followed by the division of the aqueous phase into 13 fractions using an alumina column. Notably, both the aqueous phase (20%) and all 13 fractions (ranging from 50% to 83%) displayed the ability to reduce the root length of ryegrass, a monocotyledonous weed. Liquid chromatography–mass spectrometry (LC–MS) analysis identified that fractions 3 and 7, which were effective against ryegrass but not redroot, contained Cry family proteins, including Cry10 Aa, Cry4 Ba, and Cry4 Aa. Additionally, 16s rRNA gene sequencing revealed that the ZT isolate is closely related (98.27%) to Bacillus wiedmannii. CONCLUSION: Conclusively, metabolites from the ZT bacterium hold promise for monocotyledonous weed‐targeted herbicides, providing a constructive strategy to confront agricultural issues tied to chemical herbicides and weed resistance. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The development and commercialisation of sunflower varieties tolerant to acetolactate synthase (ALS)-inhibiting herbicides some 20 years ago provided farmers with an alternative method for the cost-effective control of Orobanche cumana. In 2020, however, two independent sunflower broomrape populations from Drama (GR-DRA) and Orestiada (GR-ORE), Greece, were reported to be heavily infested with O. cumana after application of the ALS-inhibiting herbicide imazamox. Here we have investigated the race of GR-DRA and GR-ORE and determined the basis of resistance to imazamox in the two Greek O. cumana samples. Using a set of five diagnostic sunflower varieties characterised by different resistant genes with respect to O. cumana infestation, we have clearly established that the GR-ORE and GR-DRA populations belong to the invasive broomrape races G and G+, respectively. Live underground tubercles and emerged shoots were identified at the recommended field rate of imazamox for GR-DRA and GR-ORE but not for two other standard sensitive populations in a whole plant dose response test using two different herbicide-tolerant sunflower hybrids as hosts. Sequencing of the ALS gene identified an alanine 205 to aspartate mutation in all GR-ORE samples. Most GR-DRA tubercles were characterised by a second serine 653 to asparagine ALS mutation whilst a few GR-DRA individuals contained the A205D mutation. Mutations at ALS codons 205 and 653 are known to impact on the binding and efficacy of imazamox and other imidazolinone herbicides. The knowledge generated here will be important for tracking and managing broomrape resistance to ALS-inhibiting herbicides in sunflower growing regions. [ABSTRACT FROM AUTHOR]

Waterhemp (Amaranthus tuberculatus (Moq.) Sauer) is one of the most problematic weeds in the Midwestern agricultural systems in the USA. As a consequence of extensive herbicide selection pressure, many waterhemp populations across the USA evolved resistance to multiple herbicides, leading to limited options for chemical control. Genome editing tools, including CRISPR/Cas9, have great potential in weed science, especially when coupled with a gene drive system for a sustainable weed management. The application of modern biotechnological tools requires availability of an efficient regeneration and genetic transformation system. The objectives of this research were to develop an efficient protocol for successful regeneration of waterhemp via callus culture and optimize an Agrobacterium-mediated transformation method for waterhemp. Hypocotyl explants cultured on callus induction medium (CIM), C6 containing 1.0 mg L−1 kinetin and 4.0 mg L−1 2,4-D for 2 wk followed by subculture into shoot induction medium (SIM), S8 containing 3.0 mg L−1 BAP, 0.05 mg L−1 2,4-D, and 0.3 mg L−1 GA3 for 4 to 6 wk was successful in shoot regeneration. Leaf explants failed to respond to any treatment combinations tested for regeneration. Using the hypocotyl explant–based regeneration protocol optimized in this research, Agrobacterium-mediated transformation was performed using uidA and hpt genes as a proof of concept. Although transgenic plants were not regenerated, molecular characterization of the transformed calluses confirmed the presence of transgenic genes, for example uidA and hpt. This is the first report of the tissue-cultured-based regeneration and Agrobacterium-mediated transformation of hypocotyl derived calluses in waterhemp, which is a step forward in exploring the possibilities of genome editing research in weed science. [ABSTRACT FROM AUTHOR]

Weedy rice, a pervasive and troublesome weed found across the globe, has often evolved through fertilization of rice cultivars with little importance of crop‐weed gene flow. In Argentina, weedy rice has been reported as an important constraint since the early 1970s, and, in the last few years, strains with herbicide‐resistance are suspected to evolve. Despite their importance, the origin and genetic composition of Argentinian weedy rice as well its adaptation to agricultural environments has not been explored so far. To study this, we conducted genotyping‐by‐sequencing on samples of Argentinian weedy and cultivated rice and compared them with published data from weedy, cultivated and wild rice accessions distributed worldwide. In addition, we conducted a phenotypic characterization for weedy‐related traits, a herbicide resistance screening and genotyped accessions for known mutations in the acetolactate synthase (ALS) gene, which confers herbicide resistance. Our results revealed large phenotypic variability in Argentinian weedy rice. Most strains were resistant to ALS‐inhibiting herbicides with a high frequency of the ALS mutation (A122T) present in Argentinian rice cultivars. Argentinian cultivars belonged to the three major genetic groups of rice: japonica, indica and aus while weeds were mostly aus or aus‐indica admixed, resembling weedy rice strains from the Southern Cone region. Phylogenetic analysis supports a single origin for aus‐like South American weeds, likely as seed contaminants from the United States, and then admixture with local indica cultivars. Our findings demonstrate that crop to weed introgression can facilitate rapid adaptation to agriculture environments. [ABSTRACT FROM AUTHOR]

The two stresses of weed competition and salt salinity lead to crop yield losses and decline in the productivity of agricultural land. These constraints threaten the future of food production because weeds are more salt stress tolerant than most crops. Climate change will lead to an increase of soil salinity worldwide, and possibly exacerbate the competition between weeds and crops. This aspect has been scarcely investigated in the context of weed-crop competition. Therefore, we conducted a field experiment on green beans (Phaseolus vulgaris) to investigate the combined impact of weed competition and salt stress on key morpho-physiological traits, and crop yield. We demonstrated that soil salinity shifted weed composition toward salt tolerant weed species (Portulaca oleracea and Cynodon dactylon), while it reduced the presence of lower tolerance species. Weed competition activated adaptation responses in green bean such as reduced leaf mass per area and biomass allocation to the stem, unchanged stomatal density and instantaneous water use efficiency, which diverge from those that are typically observed as a consequence of salt stress. The morpho-physiological modifications caused by weeds is attributed to the alterations of light intensity and/or quality, further confirming the pivotal role of the light in crop response to weeds. We concluded that higher yield loss caused by combined salt stress and weed competition is due to impaired morpho-physiological responses, which highlights the negative interaction between salt stress and weed competition. This phenomenon will likely be more frequent in the future, and potentially reduce the efficacy of current weed control methods. Environmental stresses cause severe yield losses. In the field, these stresses occur contextually, leading to unpredictable outcomes in terms of crop productivity. Soil/water salinity will expand in the future due to climate change, and weed control will become harder due to herbicide resistance. We studied the combined effect of weed competition and salt stress on the yield of green beans (Phaseolus vulgaris), finding that the morpho-physiological adaptations induced by weed competition impair plant ability to tolerate salt stress. [ABSTRACT FROM AUTHOR]

Wet direct seeded rice (DSR) attributing floristically diverse weed flora which emerges as main constraints for its successful cultivation. Broad spectrum herbicide mixtures can be acted as weapon for mitigating this issue by nullifying the challenges like weed shift, herbicide resistance etc. Consequently, an experiment was conducted at the Institute Research Farm of ICAR-National Rice Research Institute, Cuttack, situated in the east coast plain region of India specifically in mid-central table land agro-climatic zone of Odisha during the Kharif seasons of 2020 and 2021 to assess the effectiveness of different herbicide mixtures in managing weeds successfully. The experiment was laid out in Randomized Complete Block Design encompassing 12 treatments, viz., nine post-emergence herbicide mixtures (experimental combinations for testing), one post-emergence herbicide check, one weed-free (T11) (weed-free plots were maintained by hand weeding) and one weedy check (T12), replicated thrice. The net plot size was 5.8 × 3.8 m (22.04 m² ). The test variety CR Dhan 203 was sown in 20 cm rows apart. Weed-free treatment (T11) was at par with fenoxaprop-p ethyl 6.7% EC (w/w) + ethoxysulfuron 15% WDG (w/w) (50+15) g/ha (T4 ), penoxsulam 21.7% SC+ cyhalofopbutyl 12% EC (w/v) (25+100) g/ha (T3 ), azimsulfuron 50% DF+ bispyribac sodium 10% SC (22+25) g/ha (T1 ), flucetosulfuron 10% WDG (w/w) + bispyribac sodium 10% SC (25+25) g/ha (T2 ), bispyribac sodium 10% SC + ethoxysulfuron 15% WDG (w/w) (25+15) g/ha (T5 ) for high performance in terms of grain yield. Also showed lowest weed flora dynamics and relative weed density as well. Among the herbicide treatments, fenoxaprop-p ethyl 6.7% EC (w/w) + ethoxysulfuron 15% WDG (w/w) (50+15) g/ha (T4) registered the highest weed control efficiency (86.49%) and lowest weed index (6.69%), hence demonstrating as most viable and adoptable combinations for agricultural crop production. [ABSTRACT FROM AUTHOR]

Annual bluegrass (Poa annua L.) is the most troublesome weed on golf courses in the US. Many agronomic practices intended to promote high‐quality playing surfaces favor the growth and development of annual bluegrass, resulting in high weed pressure. One commonly used herbicide for annual bluegrass control on golf courses is ethofumesate, which is a very long chain fatty acid inhibitor. Annual bluegrass resistance to this herbicide is documented and confirmed in grass seed production systems, but potential resistance on golf courses was previously unknown. The objective of this study was to determine the frequency and magnitude of potential ethofumesate resistance from a sample of US golf courses. A dose‐response experiment was initiated at Purdue University using 30 annual bluegrass populations collected from Alabama, California, Indiana, and Oregon golf courses. Ten ethofumesate doses included 0, 0.5, 1.0, 2.5, 5.0, 7.5, 10.0, 15.0, 20.0, and 40.0 lb a.i. acre−1, with 1.0 to 2.0 a.i. acre−1 as the standard label application rate for perennial ryegrass turf. A low level of resistance (R/S < 3) was found in several populations collected in each state. The mean effective dose necessary to kill 50% of the populations (ED50) was 5.1, 9.2, 3.5, and 3.4 lb a.i. acre−1 for populations from Alabama, California, Indiana, and Oregon, respectively. The most resistant population originated from California, with an ED50 of 13.2 lb a.i. acre−1. To reduce selection pressure from ethofumesate populations, golf course superintendents are encouraged to develop site‐specific weed control programs that rotate herbicide sites of action, as well as utilize diverse control tactics. Plain Language Summary: Annual bluegrass (Poa annua L.) is the most troublesome weed on US golf courses. Despite using non‐chemical control measures, this weed persists requiring the application of herbicides for its control. Ethofumesate is a commonly used herbicide where cool‐season grasses are grown, although there is a concern that recurring use of herbicides will lead to the development of resistant weeds. We set out to determine if annual bluegrass on US golf courses was developing resistance to ethofumesate. We tested 30 annual bluegrass populations collected from golf courses in Alabama, California, Indiana, and Oregon golf courses. We found annual bluegrass populations from each state that were resistant to ethofumesate. Some had a low level of resistance, while others were six times more resistant than our susceptible reference population. These results point to the need to promote diverse control strategies and a rotation of herbicides to reduce the risk of herbicide resistance development. [ABSTRACT FROM AUTHOR]

This document discusses the identification of resistant mutations in the HPPD gene in rice. The researchers found that certain mutations in the HPPD gene increased resistance to herbicides, but also resulted in decreased plant height and lower seed setting rate. The document suggests strategies for improving crop tolerance, such as combining target-site mutations with a higher background-tolerance HPPD gene and introducing the HPPD-inhibitor metabolism gene HIS1. It also recommends rotating the use of different types of HPPD herbicides to prevent the emergence of resistant weeds. [Extracted from the article]

Soybean is grown worldwide for its high protein and oil content. Weeds compete fiercely for resources, which affects soybean yields. Because of the progressive enhancement of weed resistance to herbicides and the quickly increasing cost of manual weeding, mechanical weed control is becoming the preferred method of weed control. Mechanical weed control finds it difficult to remove intra-row weeds due to the lack of rapid and precise weed/soybean detection and location technology. Rhodamine B (Rh-B) is a systemic crop compound that can be absorbed by soybeans which fluoresces under a specific excitation light. The purpose of this study is to combine systemic crop compounds and computer vision technology for the identification and localization of soybeans in the field. The fluorescence distribution properties of systemic crop compounds in soybeans and their effects on plant growth were explored. The fluorescence was mainly concentrated in soybean cotyledons treated with Rh-B. After a comparison of soybean seedlings treated with nine groups of rhodamine B solutions at different concentrations ranging from 0 to 1440 ppm, the soybeans treated with 180 ppm Rh-B for 24 h received the recommended dosage, resulting in significant fluorescence that did not affect crop growth. Increasing the Rh-B solutions reduced crop biomass, while prolonged treatment times reduced seed germination. The fluorescence produced lasted for 20 days, ensuring a stable signal in the early stages of growth. Additionally, a precise inter-row soybean plant location system based on a fluorescence imaging system with a 96.7% identification accuracy, determined on 300 datasets, was proposed. This article further confirms the potential of crop signaling technology to assist machines in achieving crop identification and localization in the field. [ABSTRACT FROM AUTHOR]

A key challenge in the management of populations is to quantify the impact of interventions in the face of environmental and phenotypic variability. However, accurate estimation of the effects of management and environment, in large‐scale ecological research is often limited by the expense of data collection, the inherent trade‐off between quality and quantity, and missing data.In this paper we develop a novel modelling framework, and demographically informed imputation scheme, to comprehensively account for the uncertainty generated by missing population, management, and herbicide resistance data. Using this framework and a large dataset (178 sites over 3 years) on the densities of a destructive arable weed (Alopecurus myosuroides) we investigate the effects of environment, management, and evolved herbicide resistance, on weed population dynamics.In this study we quantify the marginal effects of a suite of common management practices, including cropping, cultivation, and herbicide pressure, and evolved herbicide resistance, on weed population dynamics.Using this framework, we provide the first empirically backed demonstration that herbicide resistance is a key driver of population dynamics in arable weeds at regional scales. Whilst cultivation type had minimal impact on weed density, crop rotation, and earlier cultivation and drill dates consistently reduced infestation severity.Synthesis and applications: As we demonstrate that high herbicide resistance levels can produce extremely severe weed infestations, monitoring herbicide resistance is a priority for farmers across Western Europe. Furthermore, developing non‐chemical control methods is essential to control current weed populations, and prevent further resistance evolution. We recommend that planning interventions that centre on crop rotation and incorporate spring sewing and cultivation to provide the best reductions in weed densities. More generally, by directly accounting for missing data our framework permits the analysis of management practices with data that would otherwise be severely compromised. [ABSTRACT FROM AUTHOR]

Bromus sterilis L. (barren brome) is one of the most economically important noxious grass weeds in the winter cereal fields of Europe. Its ecological behaviour in this agro-climatic region should be assessed for effective weed control strategies. The present study was conducted to assess the dormancy and germination response of the B. sterilis population from the Czech Republic under thermal, light, and stress conditions. The dormancy loss experiment revealed that seeds exposed to the light regime showed a remarkably lower percentage of germination, and under alternating temperatures of 10/20 °C in dark conditions, rapid loss of primary dormancy was observed. This population was found to germinate across a wide temperature range of 5-35 °C, with the highest germination rate at 25 °C (T50 = 1.14 days in dark, 1.21 days in light) and the germination time increased with decreasing temperatures below 25 °C. Further, due to fitness advantage, herbicide-resistant (R) biotypes were found to be more stress-tolerant than susceptible (S) biotypes under salinity and drought conditions. In the highest stress conditions, the germination of S biotypes was negligible, while R biotypes can germinate under high stress, but germination decreased below 25 °C. The current findings may add value to effective weed control strategies using prediction models based on seed dormancy and germination values under different hydrothermal conditions. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Hu et al. (2023), 242: 333–343. [ABSTRACT FROM AUTHOR]

See also the Commentary on this article by Zhang et al., 242: 327–330. [ABSTRACT FROM AUTHOR]

We reviewed and performed a quantitative synthesis on herbicide‐resistant weeds from rain‐fed crops in Argentina. Twenty‐four weed species distributed in the main extensive crops (soybean, maize, wheat, barley, oilseed rape, sunflower, chickpea and peanut) have evolved herbicide resistance. Of the total, 54% are grasses, 88% are annual species and 63% are cross‐pollinated species. The most representative families were Poaceae with 54% resistant species, followed by Brassicaceae with 17%, and Asteraceae with 13%. Buenos Aires, Santa Fe and Córdoba were the provinces with the most documented cases of resistance (35%, 33% and 30%, respectively). The proportion of cases resistant to pre‐emergence herbicides was 10%, whereas the proportion of cases resistant to post‐emergence herbicides was 90%. Glyphosate was the herbicide with the highest incidence (92%) of resistance among weed species, followed by 29% of species that evolved resistance to ALS‐inhibiting herbicides. Whereas resistance to auxin‐like herbicides comprised 17% of the weed species, acetyl‐CoA carboxylase (8%) and protoporphyrinogen oxidase (4%) inhibiting herbicides showed the least incidence of resistance evolution among weeds. The highest number of resistant species was identified in soybean (19), followed by maize (13), wheat/barley (10) and fallow (9). Weed species with a higher number of resistant populations to a higher number of herbicide mode of action were Amaranthus hybridus, A. palmeri, Lolium multiflorum and Raphanus sativus. The change in the production system since the mid‐1990s, based on the use of herbicides (glyphosate mainly) to control weeds, is likely to account for the notorious increase in the average rate of evolution of herbicide‐resistant weeds in Argentina. [ABSTRACT FROM AUTHOR]

Herbicide resistance in western Canada has increased interest in alternative weed management strategies. Physical impact mills, a form of harvest weed seed control, have been identified as a strategy that may be well suited for Canadian use. The efficacy of the Harrington Seed Destructor, a physical impact mill, was evaluated in 20 producer fields in Alberta on a wide spectrum of weed species over 3 years. Significant differences in weed densities between the physical impact mill treatment and the regular harvest densities were few; however, some population density reductions were observed. Measurable reductions in weed densities may have been limited by the short timeframe of the experiment, the high initial densities of the weeds, or the targeted weed species having dormancy or longer term seedbanks. Additionally, identified knowledge gaps on how best to optimize physical impact mill efficacy may have reduced the efficacy of the physical impact mill in this study. This study showed no conclusive evidence for the efficacy of a physical impact mill on tested weed species under field conditions. However, it did provide a number of important considerations for future studies. [ABSTRACT FROM AUTHOR]

Societal awareness, demand for innovative food systems and increasing herbicide resistance have induced policy, regulatory and research actions towards the adoption of sustainable weed management, which is based on sustainable, integrated and ecological principles. The study investigates farmers' perceptions with regard to sustainable weed management, considering that the adoption of relevant practices depends on a set of farmer-specific and innovation-specific attributes. To achieve this purpose, an on-site survey was conducted in Greece and Tunisia based on a structured questionnaire, which was completed by 105 arable farmers in total. The questionnaire was designed to record farmers' opinions and preferences regarding aspects related to sustainable weed management, such as innovation and the decision making process. Using descriptive statistics methods, the study pinpointed significant differences between the responses of Greek and Tunisian farmers due to their particular needs and characteristics, suggesting thus the integration of targeted approaches towards the expansion of sustainable weed management. [ABSTRACT FROM AUTHOR]

Understanding non-target-site resistance (NTSR) to herbicides represents a pressing challenge as NTSR is widespread in many weeds. Using giant duckweed (Spirodela polyrhiza) as a model, we systematically investigated genetic and molecular mechanisms of diquat resistance, which can only be achieved via NTSR. Quantifying the diquat resistance of 138 genotypes, we revealed an 8.5-fold difference in resistance levels between the most resistant and most susceptible genotypes. Further experiments suggested that diquat uptake and antioxidant-related processes jointly contributed to diquat resistance in S. polyrhiza. Using a genome-wide association approach, we identified several candidate genes, including a homolog of dienelactone hydrolase, that are associated with diquat resistance in S. polyrhiza. Together, these results provide new insights into the mechanisms and evolution of NTSR in plants. [ABSTRACT FROM AUTHOR]

Weeds are increasingly documented with evolved resistance to herbicides globally. Three species have been reported as resistant in maize crops in New Zealand: Chenopodium album to atrazine and dicamba, Persicaria maculosa to atrazine and Digitaria sanguinalis to nicosulfuron. Despite knowledge of these cases, the distribution of these resistant biotypes is unknown. This study aimed to determine the prevalence of known resistant weeds in major maize growing areas in New Zealand, and to pro-actively screen other species for resistance. Weed seeds of broadleaf and grass species were collected from 70 randomly selected maize growing farms in the North Island in 2021–2022. Seeds were grown and treated with herbicides at recommended field rates. Atrazine-resistant C. album were recorded in a third of surveyed farms and nicosulfuron-resistant D. sanguinalis in a sixth. Half of Waikato farms and a quarter of Bay of Plenty farms (no Hawkes Bay or Wellington farms) had atrazine-resistant C. album. Dicamba-resistant C. album were not detected, nor were atrazine-resistant P. maculosa. Nicosulfuron resistant D. sanguinalis was recorded in 19% of Waikato farms, 6% of Bay of Plenty farms and 9% of Hawkes Bay farms (no Wellington farms). Amaranthus spp., Fallopia convolvulus, Persicaria spp., Solanum spp., Echinochloa crus-galli, Panicum spp. and Setaria spp. were not resistant to any of the herbicides tested. Twenty-nine to 52% of maize farms in the North Island are estimated to have herbicide resistant weeds. Resistance is common in maize farms in Waikato and western Bay of Plenty. Resistance is rare in southern regions, with only one instance of nicosulfuron-resistant D. sanguinalis and no resistant C. album. Most annual weeds in maize are not resistant to herbicides; although atrazine resistant C. album is widespread, it is currently controlled with alternative herbicides. Resistant D. sanguinalis appears to be an emerging problem. [ABSTRACT FROM AUTHOR]

• Weeds and other pests: insects and pathogens, are responsible for huge economic losses in agriculture. • Unjudicious use of synthetic pesticides creates resistance among pests. • Allelochemicals can be used for pest management for sustainable agriculture under changing climatic conditions. • Allelochemicals with therapeutic potential can improve human health. Agricultural productivity is stricken by abiotic and biotic constraints. The global population is rising continuously, intensifying the pressure on crop productivity. An increase in pest populations, plant pathogens and invasive plants due to climate-related changes can cause significant reductions in yields on arable land. The excessive use of synthetic pesticides has triggered environmental pollution thereby, health hazards. Sustainable agriculture is now focused on ensuring global food security through a range of innovative and environmentally friendly approaches for pest control. Crop plants release allelochemicals into the environment by leaching, foliar decomposition and volatilization from different parts of the plant. These phytochemicals can inhibit the growth of weeds and can be toxic to crop pests. The present review focuses on utilizing allelochemicals as biopesticides for the control of pests, pathogens and weeds. It also sheds light on the use of allelochemicals for the production of plant-based pharmaceuticals. Furthermore, the studies on gene regulation for enhancement of allelochemicals and genetic modifications for crop improvement will pave the way for future research on the development of phytochemicals as a potential tool for sustainable agriculture in agroecosystems. [ABSTRACT FROM AUTHOR]

Black-grass (Alopecurus myosuroides) is one of the most problematic agricultural weeds of Western Europe, causing significant yield losses in winter wheat (Triticum aestivum) and other crops through competition for space and resources. Previous studies link black-grass patches to water-retaining soils, yet its specific adaptations to these conditions remain unclear. We designed pot-based waterlogging experiments to compare 13 biotypes of black-grass and six cultivars of wheat. These showed that wheat roots induced aerenchyma when waterlogged whereas aerenchyma-like structures were constitutively present in black-grass. Aerial biomass of waterlogged wheat was smaller, whereas waterlogged black-grass was similar or larger. Variability in waterlogging responses within and between these species was correlated with transcriptomic and metabolomic changes in leaves of control or waterlogged plants. In wheat, transcripts associated with regulation and utilisation of phosphate compounds were upregulated and sugars and amino acids concentrations were increased. Black-grass biotypes showed limited molecular responses to waterlogging. Some black-grass amino acids were decreased and one transcript commonly upregulated was previously identified in screens for genes underpinning metabolism-based resistance to herbicides. Our findings provide insights into the different waterlogging tolerances of these species and may help to explain the previously observed patchiness of this weed's distribution in wheat fields. Black-grass is a problematic weed of winter wheat. To better understand if waterlogging tolerance increases its weediness, we conducted controlled waterlogging studies comparing the physiology and molecular responses of black-grass and wheat. These revealed differences in roots and aerial tissues within and between species. Molecular analyses showed that wheat mounts a significant molecular response, altering gene expression and metabolites with waterlogging, whereas black-grass showed minimal responses to waterlogging despite its apparent tolerance. This article belongs to the Collection Flooding Stress and Hypoxic Responses in Plants. [ABSTRACT FROM AUTHOR]

BACKGROUND: Soil seedbanks have been recognized as one of the crucial components of agricultural ecosystems. However, studies on the shift in structure and biodiversity of soil seedbanks in herbicide‐resistant crop systems are limited, and a functional trait perspective of the soil seedbank is often overlooked. RESULTS: A 6 years experiment was conducted to investigate the roles of region, crop system, and weed management strategy on species richness, functional trait diversity, and composition of the weed seedbank. Species richness was different across the interaction of region and crop system, while functional trait diversity only showed difference across regions. Species and functional trait compositions were affected by the interaction of region and crop system. Specifically, the compositional difference among crop systems was mainly determined by the significant heterogeneity of group dispersion. CONCLUSION: Growers and practitioners should consider weed functional traits in developing lasting agricultural management strategies. Long‐term weed research should draw attention to the impact of transgenic crop systems and specific management tactics on weed dispersal, functional composition, and resistance evolution of weed species in such agroecosystems. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

New Zealand has fewer numbers of herbicide-resistant crop weeds than many other highly developed economies, yet these numbers are likely to increase in the future. A clear indication of the scale of this risk can be derived from the predictable structure in the global occurrence of herbicide-resistant weeds that results from similarities in agronomic and environmental conditions. Hierarchical cluster analysis was used to identify groups of countries with similar herbicide-resistant weed assemblages to New Zealand. A distinct cluster of 11 European countries with strong climatic and agronomic affinities to New Zealand was identified. The combined assemblage of herbicide-resistant weeds within this cluster consisted of 27 species and the potential risk of a species evolving herbicide resistance was calculated as its frequency among these European countries. Species with potential to become herbicide resistant in New Zealand included established crop weeds (e.g. Senecio vulgaris, Tripleurospermum inodorum) as well as species only encountered as contaminants of seed imports (e.g. Alopecurus myosuroides, Apera spica-venti). All eight species already known to be herbicide-resistant in New Zealand were found in the high-risk assemblage and this indicates that the analysis provided a realistic measure of future risk. [ABSTRACT FROM AUTHOR]

Faced with the biodiversity extinction crisis and climate change, alternative approaches to food production are urgently needed. Decades of chemical-based weed control have resulted in a dramatic decline in weed diversity, with negative repercussions for agroecosystem biodiversity. The simplification of cropping systems and the evolution of herbicide resistance have led to the dominance of a small number of competitive weed species, calling for a more sustainable approach that considers not only weed abundance but also community diversity and composition. Agroecological weed management involves harnessing ecological processes to minimize the negative impacts of weeds on productivity and maximize biodiversity. However, the current research effort on agroecological weed management is largely rooted in agronomy and field-scale farming practices. In contrast, the contributions of landscape-scale interventions on agroecological weed management are largely unexplored (e.g., interventions to promote pollinators and natural enemies or carbon sequestration). Here, we review current knowledge of landscape effects on weed community properties (abundance, diversity, and composition) and seed predation (a key factor in agroecological weed management). Furthermore, we discuss the ecological processes underlying landscape effects, their interaction with in-field approaches, and the implications of landscape-scale change for agroecological weed management. Notably, we found that (1) landscape context rarely affects total weed abundance; (2) configurational more than compositional heterogeneity of landscapes is associated with higher alpha, beta, and gamma weed diversity; (3) evidence for landscape effects on weed seed predation is currently limited; and (4) plant spillover from neighboring habitats is the most common interpretation of landscape effects on weed community properties, whereas many other ecological processes are overlooked. Strikingly, the drivers of weed community properties and biological regulation at the landscape scale remain poorly understood. We recommend addressing these issues to better integrate agroecological weed management into landscape-scale management, which could inform the movement towards managing farms at wider spatiotemporal scales than single fields in a single season. [ABSTRACT FROM AUTHOR]

BACKGROUND: Corn poppy (Papaver rhoeas) is the most damaging broadleaf weed in France. Massively parallel amplicon sequencing was used to investigate the prevalence, mode of evolution and spread of resistance‐endowing ALS alleles in 422 populations randomly sampled throughout poppy's range in France. Bioassays were used to detect resistance to the synthetic auxin 2,4‐D in 43 of these populations. RESULTS: A total of 21 100 plants were analysed and 24 mutant ALS alleles carrying an amino‐acid substitution involved or potentially involved in resistance were identified. The vast majority (97.6%) of the substitutions occurred at codon Pro197, where all six possible single‐nucleotide non‐synonymous substitutions plus four double‐nucleotide substitutions were identified. Changes observed in the enzymatic properties of the mutant ALS isoforms could not explain the differences in prevalence among the corresponding alleles. Sequence read analysis showed that mutant ALS alleles had multiple, independent evolutionary origins, and could have evolved several times independently within an area of a few kilometres. Finally, 2,4‐D resistance was associated with mutant ALS alleles in individual plants in one third of the populations assayed. CONCLUSION: The intricate geographical mosaic of mutant ALS alleles observed is the likely result of the combination of huge population sizes, multiple independent mutation events and human‐mediated spread of resistance. Our work highlights the ability of poppy populations and individual plants to accumulate different ALS alleles and as yet unknown mechanisms conferring resistance to synthetic auxins. This does not bode well for the continued use of chemical herbicides to control poppy. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recently, suspected cyhalofop‐butyl‐resistant populations of allohexaploid weed Echinochloa crus‐galli var. crus‐galli were discovered in rice fields in Aichi Prefecture, Japan. Analyzing the target‐site ACCase genes of cyhalofop‐butyl helps understand the resistance mechanism. However, in E. crus‐galli, the presence of multiple ACCase genes and the lack of detailed gene investigations have complicated the analysis of target‐site genes. Therefore, in this study, we characterized the herbicide response of E. crus‐galli lines and thoroughly characterized the ACCase genes, including the evaluation of gene mutations in the ACCase genes of each line. RESULT: Four suspected resistant lines collected from Aichi Prefecture showed varying degrees of resistance to cyhalofop‐butyl and other FOP‐class ACCase inhibitors but were sensitive to herbicides with other modes of action. Through genomic analysis, six ACCase loci were identified in the E. crus‐galli genome. We renamed each gene based on its syntenic relationship with other ACCase genes in the Poaceae species. RNA‐sequencing analysis revealed that all ACCase genes, except the pseudogenized copy ACCase2A, were transcribed at a similar level in the shoots of E. crus‐galli. Mutations known to confer resistance to FOP‐class herbicides, that is W1999C, W2027C/S and I2041N, were found in all resistant lines in either ACCase1A, ACCase1B or ACCase2C. CONCLUSION: In this study, we found that the E. crus‐galli lines were resistant exclusively to ACCase‐inhibiting herbicides, with a target‐site resistance mutation in the ACCase gene. Characterization of ACCase loci in E. crus‐galli provides a basis for further research on ACCase herbicide resistance in Echinochloa spp. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Weed control has relied on the use of organic and inorganic molecules that interfere with druggable targets, especially enzymes, for almost a century. This approach, although effective, has resulted in multiple cases of herbicide resistance. Furthermore, the rate of discovery of new druggable targets that are selective and with favorable environmental profiles has slowed down, highlighting the need for innovative control tools. The arrival of the biotechnology and genomics era gave hope to many that all sorts of new control tools would be developed. However, the reality is that most efforts have been limited to the development of transgenic crops with resistance to a few existing herbicides, which in fact is just another form of selectivity. Proteolysis‐targeting chimera (PROTAC) is a new technology developed to treat human diseases but that has potential for multiple applications in agriculture. This technology uses a small bait molecule linked to an E3 ligand. The 3‐dimensional structure of the bait favors physical interaction with a binding site in the target protein in a manner that allows E3 recruitment, ubiquitination and then proteasome‐mediated degradation. This system makes it possible to circumvent the need to find druggable targets because it can degrade structural proteins, transporters, transcription factors, and enzymes without the need to interact with the active site. PROTAC can help control herbicide‐resistant weeds as well as expand the number of biochemical targets that can be used for weed control. In the present article, we provide an overview of how PROTAC works and describe the possible applications for weed control as well as the challenges that this technology might face during development and implementation for field uses. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Conyza bonariensis L. (hairy fleabane) is a significant weed in production systems, especially due to its evolving resistance to various herbicides. In Uruguay, control failures of C. bonariensis have been reported following the use of glyphosate and ALS inhibitors. The objective of this study was to investigate the occurrence of the multiple and cross-resistance of C. bonariensis to glyphosate, chlorimuron, and diclosulam, and to assess the efficacy of alternative herbicides against these resistant biotypes. Seeds were collected from sites where plants had survived herbicide applications during the 2019/2020 and 2020/2021 seasons. Following initial screenings, biotypes were selected to establish independent dose–response curves for glyphosate, diclosulam, and chlorimuron. For each herbicide, four biotypes of C. bonariensis were tested: one susceptible (S), two putatively moderately resistant (MR) biotypes, and one putatively highly resistant (R) biotype. In each assay, eight herbicide doses were used (1/32; 1/16; 1/8; 1/2; 1; 2; and 4X for S and MR biotypes, and 1/8; 1/2; 1; 2; 4; 8; and 16X for R biotypes) based on the recommended dose (1x) for each herbicide, with four repetitions per treatment. Each assay was completely replicated twice. Resistance was confirmed through testing in two plant generations (G1 and G2). The findings reveal high levels of multiple and cross-resistance in C. bonariensis to glyphosate, diclosulam, and chlorimuron. In general, herbicides with alternative action mechanisms effectively controlled C. bonariensis exhibiting multiple and cross-resistance. This study confirms the first case of C. bonariensis cross-resistance to diclosulam and chlorimuron, and the first occurrence of multiple and cross-resistance to glyphosate, diclosulam, and chlorimuron in this species. [ABSTRACT FROM AUTHOR]

The invasion of weeds into productive areas has substantial negative effects on native ecosystems as well as agricultural production systems globally. Consequently, the task of maintaining or restoring these systems will become increasingly challenging without consistent, ongoing management efforts. The intensifying emergence of herbicide resistance in numerous weed species, coupled with the unintended pollution caused by synthetic herbicides, underscores the growing necessity for alternative, environmentally friendly, and sustainable management techniques, such as the utilisation of bioherbicides. Plant pathogenic microbes play an important role in biologically management of weeds, with the utilization of plant pathogenic fungi emerging as a promising area of study for novel research trends aimed at weed management without reliance of herbicides and to mitigate environmental pollution. A potential solution to decreasing pesticide usage involves the development of bioherbicides containing fungal active ingredients. Among the most commonly utilised fungi in bioherbicides are genera like Alternaria, Colletotrichum, Cercospora, Fusarium, Phomopsis, Phytophthora, Phoma, and Puccinia. Increased weed resistance to herbicides has influenced new strategies for weed management, with some fungi from genera such as Colletotrichum and Phoma already employed for weed control. Nonetheless, it is evident from reviews that further research is imperative in this domain, with particular emphasis on analysing the efficacy of each plant pathogenic fungi. [ABSTRACT FROM AUTHOR]

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Agriculture is an important part of the India's economy. India ranks first in net cropland area in the world with 179.8 mha which is 9.6% of global net cropland area and India's agriculture sector makes up 16% of the country's economy, while accounting for 49% of employment (FAOSTAT, 2020). The rice-wheat cropping system (RWCS) is extensive in the subtropical areas of the Indo-Gangetic Plains of India while maize-wheat is widespread in tropical, sub-tropical and warm temperate regions. In north India, rice is grown in the summer season (June/July to September/October) whereas wheat is grown in the winter season (October/November to February/March). The area under wheat in India was 30.59 mha with an annual production of 99.78 mt and average productivity of 3.22 t ha-1 (Anonymous, 2019). The weeds are accounting as a major factor in yield reduction of wheat. The mechanical weed control is not so much effective in controlling weeds in wheat because of narrow inter row spacing. Further, the manual weeding is not much feasible because of mimicry weeds like Phalaris minor which are very much similar to wheat during initial stages. Therefore, the role of herbicides cannot be neglected. But the continuous application of herbicides with same mode of action year by year has resulted in evolution of herbicide resistance in weed species. The management of herbicide resistant weeds in crop production is a major challenge. This review mainly focuses on the current status of herbicide resistant weeds in India associated with wheat along with their management strategies. [ABSTRACT FROM AUTHOR]

Context: Wild oats (Avena spp.), brome grass (Bromus spp.) and barley grass (Hordeum spp.) are significant grass weeds of crop production in south-eastern Australia. The presence of herbicide resistance in these weed species is a major limiting factor on both productivity and profitability. Aims: We aimed to determine the distribution of herbicide resistance in these weed species across south-eastern Australia. Methods: Several surveys were conducted in randomly selected fields across four states in south-eastern Australia over a 5-year period, collecting 663 wild oats, 366 brome grass and 262 barley grass samples that were screened for resistance with up to five different herbicide groups or subgroups. Key results: In wild oats, resistance was most common to clodinafop-propargyl ('fop' ACCase inhibitor), with 22% of samples resistant and resistance detected in all regions except Tasmania. Resistance to sulfonylurea herbicides (ALS inhibitors) was less common with 7% of samples resistant, but regionally more variable. For both brome grass and barley grass, a greater proportion of samples was resistant to the sulfonylurea mesosulfuron-methyl, at 24% and 19%, respectively, than to quizalofop-ethyl ('fop' ACCase inhibitor). Conclusions: Resistance was recorded in all three species, with differences in the extent of resistance among herbicide groups and regions. Overall, a higher than average frequency of wild oats resistance to clodinafop-propargyl was found in regions of New South Wales and of brome grass and barley grass resistance to mesosulfuron-methyl in regions of South Australia. However, for all species some herbicides were still effective on all samples. Implications: The presence of significant herbicide resistance in these weed species indicates that management decisions need to include consideration of resistance to enable successful control measures. Herbicide-resistant weeds are a major threat to crop production, with wild oats, brome grass and barley grass being species of concern in Australia. Surveys of south-eastern Australia conducted over a 5-year period found >20% of wild oats samples to be resistant to Group 1 'fop' herbicides. For both brome grass and barley grass, resistance was highest to the Group 2 sulfonylurea herbicides, at 24% and 19%, respectively. [ABSTRACT FROM AUTHOR]

In 35 years of routine screening for herbicide resistance, a total of 3758 seed sample/herbicide combinations were assayed. Resistance testing was done in either pots in glasshouses (chlortoluron, fenoxaprop and mesosulfuron‐methyl + iodosulfuron‐methyl sodium) or Petri‐dishes in incubators (sethoxydim, cycloxydim and pendimethalin). With all herbicides, the relationship between herbicide efficacy and year of sampling was linear, with the slope representing the annual loss of efficacy. This was higher for the ALS inhibitors mesosulfuron + iodosulfuron (3.73% year−1) and ACCase inhibitors sethoxydim/cycloxydim (1.92% year−1) and fenoxaprop (1.36% year−1) than for the substituted urea chlorotoluron (0.69% year−1) and the dinitroaniline pendimethalin (1.10% year−1). These results are consistent with other studies on the relative resistance risk associated with these different modes of action. There was also a surprisingly good correlation between results for random and non‐random resistance testing, which has also been found in studies with other weed species in Canada and Australia. This indicates that routine testing of submitted samples can replace, at least partly, the need for random surveys which tend to be both labour intensive and expensive. These results, compiled over 35 years, show the value of routine resistance screening, not only for detecting resistance at the individual field level ('micro' scale), but also the distribution, evolution and impact of resistance country‐wide ('macro' scale). However, it is important that standardised testing methods, including appropriate reference populations, are used by different testing centres to ensure consistent results. [ABSTRACT FROM AUTHOR]

Amaranthus tuberculatus is the most common weed in soybean and corn in the USA and Canada. In Israel, it has been a minor riverbank weed. However, in recent years, growing densities of this plant have been observed in field crops, orchards, and roadsides. Between 2017 and 2022, we surveyed the distribution of A. tuberculatus and collected seeds for further study. We identified three main distribution zones in Israel: the Jezreel Valley, Hula Valley, and Coastal Plain. Most of the populations were found near water sources, fishponds, barns, dairies, or bird-feeding sites, suggesting the involvement of imported grain in introducing A. tuberculatus to Israel. Populations were screened for their responses to various post-emergence herbicides (i.e., ALS, EPSPS, PPO, HPPD, and PSII inhibitors). Several populations from the Jezreel Valley were found to be putatively resistant to ALS, EPSPS, and PPO inhibitors. The responses of those populations to trifloxysulfuron, glyphosate, and carfentrazone-ethyl were also studied. A single ALS-, EPSPS- and PPO-resistant plant was vegetatively propagated to create a clonal population, which was treated with foramsulfuron, glyphosate, and carfentrazone-ethyl. No resistance to PSII or HPPD inhibitors was observed, but resistance to herbicides that inhibit ALS, EPSPS, and PPO was observed. A clonal propagation assay revealed the existence of a population that was resistant to ALS, EPSPS, and PPO inhibitors. Since the local A. tuberculatus populations have not been exposed to herbicide selection pressure, these traits probably reached Israel through seed-mediated gene flow via imported grain. [ABSTRACT FROM AUTHOR]

The weed Chenopodium album can infest a number of agricultural systems due to its high reproductive capacity, seed dormancy, high persistence in the soil, ability to sprout and develop under adverse environmental circumstances, and other peculiar biological traits. This weed prevents the germination and/or growth of plants as well as native vegetation because of its allelopathic characteristics. Since they have the potential to reduce agricultural productivity by more than 90% and infest a wide variety of horticultural and agronomic crops, this weed poses a potential threat to food security worldwide. In consideration of these consequences, effective control measures are required. Various cultural, mechanical, and biological methods have been used to control C. album with variable degrees of success, depending on cropping systems and weed infestation levels. Since C. album's widespread herbicide tolerance has decreased the efficiency of chemical management, biological control could be a potential management strategy. In this review, we have investigated and analyzed the up-to-date information regarding the biology, current status and possibilities of biological control of C. album. [ABSTRACT FROM AUTHOR]

Weeds are undesirable and not subject to cultivation. It is known that weeds can host pathogens, however, their role as a source of beneficial organisms is poorly studied and only in individual cases. This paper is a short review of the available literature on the role of weeds as hosts of beneficial microorganisms. Some of the fungi mentioned in this review belong to Fusarium, Alternaria, Aspergillus and Trichoderma genera, while bacterial genera include Bacillus and Pseudomonas. The conclusion is that weeds are an excellent potential source of microbial organisms that can help plant development and resistance to plant diseases. [ABSTRACT FROM AUTHOR]

BACKGROUND: Weeds grow aggressively in agricultural fields, leading to reduced crop yields and an inability to meet the growing demand for food. Herbicides are currently the most effective method for weed control. However, the overuse of herbicides has resulted in the evolution of resistance mutants and has caused environmental pollution. Therefore, new technologies are urgently required to address this global challenge. RESULTS: We report a copper‐benzene‐1,4‐dicarboxylate metal organic framework (Cu‐BDC MOF)‐functionalized carboxyl hollow mesoporous silica (HMS‐COOH) delivery system for the pH‐controlled release of the acetyl‐CoA carboxylase (ACCase)‐inhibiting herbicide quizalofop‐p‐ethyl (QE). The delivery system (QE@HMS@Cu‐BDC) enabled the efficient control of barnyard grasses that are susceptible and resistant to ACCase‐inhibiting herbicides, which showed 93.33% and 88.33% FW control efficacy at 67.5 g ha−1, respectively. With the lowest pH value (3), QE and copper ion were released slowly to total 70.30% and 78.55% levels (respectively) from QE@HMS@Cu‐BDC after 89 h. QE@HMS@Cu‐BDC showed better absorption, conduction, transportation and ACCase activity inhibition performance than that of QE emulsifiable concentrate (EC) in both susceptible and ACCase‐herbicide resistant barnyard grasses. In addition, with the safener effect of carrier HMS@Cu‐BDC and the aid of the safener fenchlorazole‐ethyl (FE), the application of QE@HMS@Cu‐BDC was shown to mitigate the damage caused by QE to rice plants. CONCLUSION: This work found that the new material HMS‐COOH@Cu‐BDC can be used to mitigate herbicide‐induced oxidative stress and improve rice plant safety. Futhermore, the QE@HMS‐COOH@Cu‐BDC constructed in this research might be used as an efficient nanopesticide formulation for weed controls in paddy rice fields. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Herbicides play a major role in weed management worldwide. However, herbicide resistance is a global challenge that threatens weed management and sustainable agriculture. In South Africa, over 36 years, ten weed species have evolved resistance to five modes of action. In this review, cases of herbicide resistance that were published in scientific journals, proceedings of congresses, theses or dissertations, and in the international survey of herbicide-resistant weeds, were included to give national and international scientists’ perspectives on the current status of herbicide resistance in South Africa. Since the last review was published in 2010, there have been new insights and novel techniques to document the molecular mechanism of herbicide-resistant weeds. Most cases of herbicide resistance in South Africa involved monocot and dicot weeds which are problematic in various cropping systems such as Lolium spp. (annual ryegrass), Phalaris spp. (canary grass), Avena spp. (wild oats), and Raphanus raphanistrum L. (wild radish). Understanding the extent of herbicide resistance and the molecular mechanism involved in herbicide resistance is paramount to developing novel techniques to manage herbicide-resistant weeds. Significance: • Data presented in this review help raise awareness of the threat of herbicide resistance in South Africa. • Herbicide resistance in South Africa continues to evolve steadily through a wide range of weed species and modes of action. [ABSTRACT FROM AUTHOR]

The commercialization of herbicide resistant oilseed rape is a revolutionary breakthrough in rape weeding technology. However, the high affinity between rapeseed and its relative weeds offers an effective way for the herbicide resistant genes (HRGs) to immigrate into weedy relatives' genomes, which made the potential ecological risks associated with the commercialization of HRGs in rapeseed into continuous concerning. In this paper, the types of current commercial herbicide resistant rapeseed and their resistance mechanisms were listed, and the possible mechanisms of HRG flow from rapeseed were summarized from two aspects: first, the genetic and non-genetic factors affecting the transfer of HRGs between rapeseed and its relatives were analyzed; the second is to analyze the possibility of the persistence of resistance genes in relatives' genome by the fitness comparison. Further, the risk differences between HRGs locating on different sub-genomes in rapeseed were compared, and the comprehensive control technology of resistant weeds was summarized. Combined with the cultivation situation of rapeseed in China, the suggestions for the safe commercial application of herbicide resistant rapeseed in the future and the urgent problems in the field of ecological risk of herbicide resistant rapeseed were put forward. [ABSTRACT FROM AUTHOR]

Background: Non-target site resistance (NTSR) to herbicides is a polygenic trait that threatens the chemical control of agricultural weeds. NTSR involves differential regulation of plant secondary metabolism pathways, but its precise genetic determinisms remain fairly unclear. Full-transcriptome sequencing had previously been implemented to identify NTSR genes. However, this approach had generally been applied to a single weed population, limiting our insight into the diversity of NTSR mechanisms. Here, we sought to explore the diversity of NTSR mechanisms in common ragweed (Ambrosia artemisiifolia L.) by investigating six field populations from different French regions where NTSR to acetolactate-synthase-inhibiting herbicides had evolved. Results: A de novo transcriptome assembly (51,242 contigs, 80.2% completeness) was generated as a reference to seek genes differentially expressed between sensitive and resistant plants from the six populations. Overall, 4,609 constitutively differentially expressed genes were identified, of which none were common to all populations, and only 197 were shared by several populations. Similarly, population-specific transcriptomic response was observed when investigating early herbicide response. Gene ontology enrichment analysis highlighted the involvement of stress response and regulatory pathways, before and after treatment. The expression of 121 candidate constitutive NTSR genes including CYP71, CYP72, CYP94, oxidoreductase, ABC transporters, gluco and glycosyltransferases was measured in 220 phenotyped plants. Differential expression was validated in at least one ragweed population for 28 candidate genes. We investigated whether expression patterns at some combinations of candidate genes could predict phenotype. Within populations, prediction accuracy decreased when applied to an additional, independent plant sampling. Overall, a wide variety of genes linked to NTSR was identified within and among ragweed populations, of which only a subset was captured in our experiments. Conclusion: Our results highlight the complexity and the diversity of NTSR mechanisms that can evolve in a weed species in response to herbicide selective pressure. They strongly point to a non-redundant, population-specific evolution of NTSR to ALS inhibitors in ragweed. It also alerts on the potential of common ragweed for rapid adaptation to drastic environmental or human-driven selective pressures. [ABSTRACT FROM AUTHOR]