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Setaria viridis (green foxtail) is an invasive weed species in various agricultural systems, prompting the search for effective compounds to control its germination. The species has primary and secondary dormancy depending on the time elapsed since post-harvesting, making management strategies more difficult. Several weed plants, such as Lantana camara L., can be a source of allelochemicals with herbicidal effects, being a potential candidate for the control of S. viridis. We investigated the effects of L. camara extracts on the germination and initial growth of S. viridis seeds with different degrees of dormancy and revealed a dose-dependent bioherbicide effect. Aqueous extracts of L. camara were analyzed by HPLC-DAD and applied (0.1 to 5.0 mg/mL) to 12- and 110-day post-harvest S. viridis seeds. Seeds were evaluated daily and germination percentage (GP), speed germination index (SGI), and radicle length (RL) were calculated. Phenolic acids and flavonoids were major components of the extract. Lower concentrations (0.1 and 0.5 mg/mL) stimulated and accelerated the germination of S. viridis, breaking its dormancy. Both 1.0 and 5.0 mg/mL concentrations hindered germination, especially in 12 dph seeds. The 1.0 mg/mL concentration resulted in longer roots, whereas 5.0 mg/mL inhibited root development. Lantana camara extracts potentially stimulate germination and radicle growth of S. viridis at low concentrations while inhibiting these parameters at higher doses. These results may open new possibilities for using L. camara in weed-control strategies. [ABSTRACT FROM AUTHOR]

Dittrichia viscosa (L.) Greuter, a perennial plant in the Asteraceae, has strong allelopathic activity due to the high content of various secondary metabolites. The bicyclic sesquiterpenoid α‐costic acid is the most abundant secondary metabolite of D. viscosa. Its remarkable insecticidal, antiparasitic, and phytotoxic activities point to its potential use as a natural herbicide, but information on its mode of action is lacking.To shed light on the mechanism of action of α‐costic acid in plant cells, we investigated the phytotoxicity of α‐costic acid in tomato plants (Solanum lycopersicum L.) through in vivo assays, the underlying cellular effects using biochemical assays, and the effect on subcellular organelles using confocal microscopy on tomato protoplasts incubated with organelle‐specific fluorescent probes.In vivo tests showed that α‐costic acid inhibited the growth of tomato seedlings and induced chlorosis and spot lesions in leaves. Biochemical assays demonstrated that α‐costic acid caused ion leakage, chlorophyll depletion, H2O2 overproduction, callose deposition, and membrane lipid peroxidation. Confocal microscopy demonstrated that α‐costic acid determined ROS overproduction and network disruption in mitochondria, singlet oxygen overproduction in chloroplasts, vacuole disintegration, and autophagosome formation.Overall, our data are consistent with a model according to which α‐costic acid phytotoxicity is related to oxidative stress in mitochondria and chloroplasts that induces extensive membrane damage, ultimately resulting in cell death associated with autophagy [ABSTRACT FROM AUTHOR]

Common ragweed (Ambrosia artemisiifolia) is one of the leading causes of allergenic rhinitis, as well as a major weed of many crops. Biological control with plant pathogens, such as fungi and bacteria, represents an attractive alternative to the application of synthetic herbicides to control this noxious weed. In this study, we isolated a Xanthomonas strain (designated as 10‐10) from a diseased common ragweed plant collected in southern Quebec, Canada. We characterized the bioherbicidal potential of this strain against common ragweed, and determined whether it can infect other plant species. Its genome was sequenced using PacBio's SMRT technology, enabling us to gain insight into the phylogenetic placement of this strain within the genus Xanthomonas, and to study the repertoire of virulence‐associated genes and clusters. Xanthomonas sp. 10‐10 belongs to a clearly defined subclade within clade C (group 2), which includes X. vesicatoria, X. dyei and X. pisi. While this strain is closely related to X. pisi, it represents a new species within the genus Xanthomonas. Surprisingly, this strain lacks a type III secretion system, which is the main virulence determinant in pathogenic Xanthomonas spp., but harbours an arsenal of cell wall‐degrading enzymes. The addition of the organosilicone surfactant Silwet L‐77 drastically increased the disease symptoms caused by Xanthomonas sp. 10‐10 on common ragweed plants grown under controlled conditions, but the plants remained alive. This strain also caused disease symptoms on tomato, pepper and lettuce. More research is needed to develop Xanthomonas‐based bioherbicide specifically targeting common ragweed. [ABSTRACT FROM AUTHOR]

Setaria viridis (green foxtail) is an invasive weed species in various agricultural systems, prompting the search for effective compounds to control its germination. The species has primary and secondary dormancy depending on the time elapsed since post-harvesting, making management strategies more difficult. Several weed plants, such as Lantana camara L., can be a source of allelochemicals with herbicidal effects, being a potential candidate for the control of S. viridis. We investigated the effects of L. camara extracts on the germination and initial growth of S. viridis seeds with different degrees of dormancy and revealed a dose-dependent bioherbicide effect. Aqueous extracts of L. camara were analyzed by HPLC-DAD and applied (0.1 to 5.0 mg/mL) to 12- and 110-day post-harvest S. viridis seeds. Seeds were evaluated daily and germination percentage (GP), speed germination index (SGI), and radicle length (RL) were calculated. Phenolic acids and flavonoids were major components of the extract. Lower concentrations (0.1 and 0.5 mg/mL) stimulated and accelerated the germination of S. viridis, breaking its dormancy. Both 1.0 and 5.0 mg/mL concentrations hindered germination, especially in 12 dph seeds. The 1.0 mg/mL concentration resulted in longer roots, whereas 5.0 mg/mL inhibited root development. Lantana camara extracts potentially stimulate germination and radicle growth of S. viridis at low concentrations while inhibiting these parameters at higher doses. These results may open new possibilities for using L. camara in weed-control strategies.

Essential oil (EO) allelopathy has been considered as potential applications in organic agriculture and weed management, where the EOs can be used as eco-friendly natural herbicides. Rhazya stricta is a widely distributed dwarf shrub in the Arabian Peninsula and is characterized by its toxicity. The present study aimed to investigate the chemical composition of the R. stricta EO using quantitative and qualitative analysis via Gas chromatography/ mass spectroscopy (GC-MS) and GC-flame ionization detection (GC-FID) as well as assess its phytotoxicity on weeds. Fifty-four volatile components were identified, representing 97.5% of total oil. The terpenes were found as the backbone of the oil constituents including mono- (55.28%) and sesqui-terpenes (27.35%), alongside non-terpenoid constituents (13.63%). From the overall identified oil constituents, trans-chrysanthenyl acetate (31.57%), cis-verbenol (11.84%), octadecenoic acid, methyl ester (4.84%), cubenol (4.82%), davana ether (4.79%), (E)-9-octadecenoic acid ethyl ester (3.93%) represented the abundant compounds. The EO exhibited strong phytotoxicity on the germination and seedling growth of weeds Dactyloctenium aegyptium and Chenopodiastrum murale compared to the crop Triticum aestivum. The EO showed an IC50 of 6.66, 7.75, and 6.45 mg/L for seed germination, shoot growth, and root growth, respectively for the weed D. aegyptium, while it showed 5.41, 8.33, and 6.82 mg/L for C. murale compared to 16.9, 18.5, and 19.5 for T. aestivum mg/L for seed germination, shoot growth, and root growth, respectively. The observed strong phytotoxicity could be ascribed to the higher content of the oxygenated terpenoid compounds, whereas, further study is recommended to evaluate the phytotoxicity of the major compounds either singularly or in combination against weeds and determine their mode(s) of action as bioherbicides. [ABSTRACT FROM AUTHOR]

Synthetic agrochemicals, including herbicides, cause diverse environmental and health effects that lead to searching for herbicide formulations with high biocompatibility, biosafety, and biodegradability. Developmental formulations of herbicides from biological sources, mainly microorganisms, are considered suitable alternative due to their high efficacy without affecting non-target organisms. This study prepared developmental formulations of fungal stains with notable herbicidal activity as biogranular and microemulsion preparation, followed by recording herbicidal activity against Amaranthus retroflexus and phytotoxic metabolite production. Screening of herbicidal activity was carried out by recording necrotic lesions, oxidative stress marker expression pattern, reactive oxygen species (ROS) generation rate, and membrane permeability changes. The respective formulation was prepared with viable fungal spores of soil isolates of Alternaria alternata, Paecilomyces sp., Fusarium oxysporum, and Aspergillus niger. Among the formulations prepared, biogranular followed by groundnut oil microemulsion preparation recorded maximum formulation efficacy and substantial herbicidal effect against the tested weed. Among the formulations of the fungal strain, Fusarium oxysporum biogranular and groundnut oil microemulsion revealed a significant herbicidal impact on the tested weed by showing a high rate of necrosis induction with significant ROS generation, membrane permeability changes, and oxidative stress marker expression. Biogranular formulation of F. oxysporum also supported highly stable, phytotoxic metabolites with high antibacterial activity against the plant pathogenic bacterial strain Pseudomonas syringae pv. syringae. Extracted metabolites recorded no toxic effect on the embryonic stages of zebrafish, revealing the high biocompatibility of metabolites. The present finding implies that the biogranular formulation of F. oxysporum can be used as an effective weed control and antimicrobial agent with high biocompatibility and biosafety. [ABSTRACT FROM AUTHOR]

In addition to competition, phytotoxic plant metabolites contribute to the weed-suppressing properties of cover crops, which could be the basis for the development of novel bioherbicides. We investigated the impact of five Cannabis sativa L. -derived neutral phytocannabinoids and an aqueous C. sativa tissue extract (HE) at six concentrations on the germination rate (GR) and seedling root length (RL) of Zea mays L., two monocotyledonous and two dicotyledonous weed species in laboratory Petri dish bioassays. Additionally, the effect of pre-emergence applications of HE, cannabidiol (CBD), and cannabidivarin (CBDV) formulations on GR and shoot dry matter (SDM) were examined in greenhouse pot studies. The effects of phytocannabinoids and HE were analyzed in dose-response curves. For the highest rates, the effects on GR, RL and SDM were calculated by ANOVA and HSD test (p < 0.05). HE exhibited the greatest suppression on GR and RL for all plant species in the Petri dish bioassay, with RGR, RL exceeding −90%. Phytocannabinoids reduced mainly RL of all plants and decreased the GR of most weed species. Effects varied among plants and phytocannabinoids, with CBDV and CBD showing similar high inhibitory effects on RL as HE in the Petri dish bioassay. All pre-emergence applications resulted in a positive RGR across all studied plants and in a positive RSDM in Z. mays and Echinochloa crus-galli (L.) P. Beauv, whereas in the other weed species the RSDM was negative. In conclusion, phytocannabinoids play a major role in weed suppression of HEs. CBDV and CBD are the most promising candidates for bioherbicide development especially against annual dicotyledonous weed species. [ABSTRACT FROM AUTHOR]

This study explores the bioconversion of diosgenin by Yarrowia lipolytica P01a, focusing on enhancing the antioxidant, antifungal, and herbicidal activities of the resulting extracts. The bioconversion process, involving glycosylation and hydroxylation, produced significant amounts of protodioscin and soyasaponin I. The extracts showed superior antioxidant activity, with up to 97.02% inhibition of ABTS· radicals and 33.30% inhibition of DPPH· radicals at 1000 mg L−1 of diosgenin. Antifungal assays revealed strong inhibitory effects against Botrytis cinerea, Alternaria sp., and Aspergillus niger, with maximum inhibition rates of 67.34%, 35.63%, and 65.53%, respectively. Additionally, the herbicidal activity of the bioconverted extracts was comparable to commercial herbicides, achieving 100% inhibition of seed germination in both monocotyledonous and dicotyledonous plants. These findings suggest that the Y. lipolytica P01a-mediated bioconversion of diosgenin could provide a sustainable and eco-friendly alternative for developing natural biofungicides and bioherbicides. [ABSTRACT FROM AUTHOR]

Alligator weed (Alternanthera philoxeroides), originally from South America, is a notorious semi‐aquatic invasive species in many countries, including India. Due to its amphibious nature, it not only damages the aquatic environment but is also detrimental to the terrestrial ecosystem. To seek an environmentally sound control option for alligator weed, this study focused on selecting an appropriate mycoherbicidal agent. A series of steps from field survey‐based collection, isolation and selection of promising fungal strains, followed by host range determination to biocontrol potential studies against the weed were undertaken. Twenty‐three phytopathogenic fungi were isolated, and among these, the fungi with the highest herbicidal activity (> 90% disease severity) were subjected to morphological and molecular characterisation and identified as Alternaria alternantherae (= Nimbya alternanthera). The fungus and its crude metabolites were tested against 76 plant species, showing a relatively narrow host range. This fungal species is being reported from West Bengal, India, for the first time. Although the fungus has been considered as a potential biocontrol tool against alligator weed in countries such as Australia, Brazil and China, long‐term, detailed research for A. alternantherae and its active metabolites to be developed as bioherbicides against alligator weed remains indispensable. [ABSTRACT FROM AUTHOR]

Lai (Durio kutejensis Hassk. Becc) an endemic plant of Kalimantan-Indonesia leaves contain secondary metabolites as allelochemicals (alkaloids, flavonoids, saponins, phenols, and steroids). We investigated the allelopathic effects of lai leaf extract on the seed germination and early growth of weeds (Ruellia tuberosa L. and Amaranthus spinosus L.) and crops (Oryza sativa L. and Zea mays L.). We conducted two experiments: Germination bioassay and Early growth greenhouse bioassay consisting of 0 (Control), 25, 50 and 75 % leaf extracts. The leaf extracts significantly decreased the germination and early growth of both test weeds and crops: Germination (%) (100 to 26.66 %), shoot length (9.40 to 3.16 cm); germination index (3.30 to 0.36); vigour index (9.40 to 0.84); biomass 1.43 to 0.14 g); and chlorophyll a (0.45 to 0.016 mg/L), b (0.077 to 0.024 mg/L), and total chlorophyll (0.122 to 0.038 mg/L) contents. In contrast, the extract increased the germination time (3.00 to 7.00 h), mortality (0 to 40 %), and phytotoxicity (0 to 2.33 %) of test plants. Higher concentrations of plant extracts were more inhibitory to germination and early growth in all test crops. Therefore, D. kutejensis leaf extract contains a natural compound that can be potentially suitable as an allelopathic-natural herbicide. In future, the results can be used to reduce the use of chemical herbicides in crop production. [ABSTRACT FROM AUTHOR]

Weeds cause significant yield loss in many agriculture crops; thus, management practices are urgently needed to alleviate losses while conserving environmental and human health. This study aimed to evaluate the allelopathic potential of Wedelia leaf and flower extracts on the germination and early growth stage of three plant species. The research was conducted using a completely randomized design experiment with two factors and four replicates. The first factor was extract sources: leaves (S1) and flowers (S2). The second factor was the concentration: control (C0) and extract concentrations of 1% (C1), 5% (C5), and 10% (C10). The extract was tested on three different plant species: soybean (Glycine max), nutsedge (Cyperus rotundus), and billygoat weed (Ageratum conyzoides). Fifty seeds of three different plants were germinated separately in Petri dishes and treated using Wedelia extracts. The allelochemicals in Wedelia leaf and flower extracts inhibited germination and induced abnormal sprouting. Wedelia leaf extract showed the most pronounced inhibitory effects and highest inhibition levels across all measured parameters. Moreover, a clear concentration-response relationship was observed, where increased extract concentration increased the degree of inhibition. These findings contribute to the development of bioherbicides and can help reduce the use of synthetic herbicides for more sustainable agriculture. [ABSTRACT FROM AUTHOR]

Weeds pose a significant challenge in agricultural activity by competing with cultivated crops for essential resources. The conventional use of chemical herbicides has demonstrated adverse impacts on the environment and human health, prompting a shift toward exploring bioherbicides. This study aimed to assess the inhibitory effects of Apus bamboo (Gigantochloa apus Kurz) leaf extract on the pre-germination phase of Brassica juncea, Asystasia gangetica, and Cyperus rotundus through bioassay and pot experiment. The research design employed a completely randomized design (CRD) with a single factor representing the concentrations of Apus bamboo leaf extract (% w/v). The concentrations tested were 0%, 5%, 10%, 15%, and 20%. Each concentration was replicated three times, resulting in 15 experimental units. Bioassay results revealed the capacity of Apus bamboo leaf extract to inhibit and disrupt B. juncea seed germination. The pot experiment results demonstrated the inhibitory effects of the extract, significantly affecting A. gangetica germination and population, A. gangetica total fresh and dry weight, and C. rotundus total dry weight. The extract exhibited strong inhibition, starting at a concentration of 15% for A. gangetica and 10% for C. rotundus. The findings suggested that Apus bamboo leaf extract holds significant potential as a bioherbicide. [ABSTRACT FROM AUTHOR]

Deleterious rhizobacteria (DRB) is one of the rhizobacteria that can be used as a bioherbicide and can stimulate plant growth. The objectives that can be obtained from this study are to determine the potential of DRB on the growth of weeds Echinochloa crusgalli and Echinochloa colona on rice. Variables observed in this study were identification of secondary metabolites, measurement of weed sprouts, percentage effectiveness of bacterial isolates against weed seeds, normal sprouts, abnormal sprouts, fresh seeds that did not grow and dead seeds. The aim of this study is to explore biological agents that can be used to control the main weeds of rice crops. This candidate could be a recommendation for environmentally friendly controls. Exploration of the DRB group was obtained by collecting soil samples around the roots of rice crops. Then isolate it, identify as morphologically and physiologically, and test it in vitro studies. The results showed that DRB had the potential to control weed growth and could stimulate the growth of rice. The application of PFA and PFB isolates had a significant effect on inhibiting the length of weed roots and buds, the average percentage of control effectiveness > 80-90%. Novelty in this study could be found as candidate groups of DRB bacteria with specific locations to control the weed Echinochloa sp. on rice crops. For society, this research could be an alternative to reduce dependence on synthetic herbicides. DRB has the potential to be formulated into a bioherbicide to control weeds. [ABSTRACT FROM AUTHOR]

The usage of chemical weedicide adversely affects the soil fertility and environment. Hence, in order to reduce the use of chemical weedicide, current study was aimed to isolate plant pathogenic microorganisms from diseased weeds and evaluate their potential as a bioherbicide in wheat field. Twelve bacterial and thirty-one fungal isolates were screened to determine their bioherbicidal activity against prevalent weeds (Avena fatua, Phalaris minor, and Chenopodium album) by using detached leaf assay and in-vitro seed testing methods. Among the forty-three isolates, two potential isolates were selected for further studies. Potential fungal isolates DGL 8C and DGL 7A with significant bioherbicidal activity were molecularly (ITS sequencing) identified as Phoma herbarum R21 (GenBank ID- ON705696) and K&lowbar;NESO2 (GenBank ID- ON705704). Phoma herbarum R21 was chosen for further research due to its superior herbicidal effect and positive influence on wheat growth. Effective herbicidal activity (up to 90%) of potential isolate was obtained in pre-germination testing, compared to control. Cell free culture filtrate (CFCF) treatment showed nonspecific inhibition in the germination of weeds and wheat. While, CFCF selectively deteriorated the target weeds in post-germination treatment. Phoma herbarum R21 enhanced the growth of Durum wheat varieties Poshan and Tejas, as it promoted the growth of shoot, root, and fresh weight up to 88% compared to control. Phoma herbarum R21 significantly inhibited the growth of phytopathogenic fungi up to 57%. In this study, Phoma herbarum R21 was identified as a potential bioherbicide against the weeds of wheat along with its growth promoting and antifungal activities. [ABSTRACT FROM AUTHOR]

Eritadenine from shiitake mushroom is a secondary metabolite with hypocholesterolemic, hypotensive and antiparasitic properties, thus promising for pharmaceutical and agricultural applications. Eritadenine is obtained from submerged mycelial cultures of shiitake, but the actual yields remain unsatisfactory to explore potential applications or industrial-scale production. In this study, green and blue LED lights were tested to increase yields of eritadenine in submerged cultures of shiitake. Notably, blue LEDs increased yields by 13–14 times, reaching 165.7 mg/L, compared to darkness (11.2 mg/L) and green light (12.1 mg/L) (p

Weeds cause significant agricultural losses worldwide, and herbicides have traditionally been the main solution to this problem. However, the extensive use of herbicides has led to multiple cases of weed resistance, which could generate an increase in the application concentration and consequently a higher persistence in the environment, hindering natural degradation processes. Consequently, more environmentally friendly alternatives, such as microbial bioherbicides, have been sought. Although these bioherbicides are promising, their efficacy remains a challenge, as evidenced by their limited commercial and industrial production. This article reviews the current status of microbial-based bioherbicides and highlights the potential of cell-free metabolites to improve their efficacy and commercial attractiveness. Stirred tank bioreactors are identified as the most widely used for production-scale submerged fermentation. In addition, the use of alternative carbon and nitrogen sources, such as industrial waste, supports the circular economy. Furthermore, this article discusses the optimization of downstream processes using bioprospecting and in silico technologies to identify target metabolites, which leads to more precise and efficient production strategies. Bacterial bioherbicides, particularly those derived from Pseudomonas and Xanthomonas, and fungal bioherbicides from genera such as Alternaria, Colletotrichum, Trichoderma and Phoma, show significant potential. Nevertheless, limitations such as their restricted range of action, their persistence in the environment, and regulatory issues restrict their commercial availability. The utilization of cell-free microbial metabolites is proposed as a promising solution due to their simpler handling and application. In addition, modern technologies, including encapsulation and integrated management with chemical herbicides, are investigated to enhance the efficacy and sustainability of bioherbicides. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are natural products widely used in sustainable agrochemistry, not only because they are biodegradable and safe but also because they are regarded as alternatives to chemical fungicides against fungal species that attack crops. Allelopathy, another field of study, falls within the most recent and sustainable strategies applied to weed suppression to replace synthetic herbicides. Therefore, this study reports the chemical composition and allelopathic and antifungal effects of the EOs extracted from Calyptranthes concinna dried leaves (Cc-EO) and its pure major constituent elemicin. Their antifungal activities were evaluated by the disk diffusion method (DDM) at doses between 0.05 mg/mL and 0.4 mg/mL of Cc-EO and elemicin. The allelopathic effect was evaluated by studying the inhibition of germination and the growth of Lactuca sativa seeds. The chemical composition of Cc-EO was determined by GC-MS and GC-FID analyses. The major constituents of Cc-EO were elemicin (60.5%), α-cadinol (9.0%) and caryophyllene oxide (8.3%). Cc-EO and elemicin were assayed in vitro against 17 fungi of agronomic interest (Aspergillus niger, A. flavus, A. nomius, Penicillium digitatum, P. expansum, Sclerotinia sclerotiorum, S. rolfsii, S. minor, Fusarium graminearum, Myrothecium verrucaria, Corynespora cassiicola, Erwinia psidii, Colletotrichum musae, Alternaria carthami, Rhizoctonia solani, Rhizopus stolonifer and Macrophomina phaseolina). The concentration of Cc-EO (0.4 mg/mL) inhibited 100% of the mycelium growth of seven strains, equal to the fungicide fluazinam, which was used as a positive control. Elemicin showed antifungal activity against all fungi at all concentrations under investigation (above 50%). A strong allelopathic effect was recorded for Cc-EO and elemicin at the dose of 0.28 mg/mL, with the almost total inhibition of germination. This study revealed, for the first time, the strong and remarkable fungicidal and allelopathic effects of Cc-EO and elemicin, an important finding for the agrochemical field. [ABSTRACT FROM AUTHOR]

Dodder (Cuscuta spp.) is a dangerous parasitic plant that causes serious damage to crop production and is challenging to eliminate. Herbicide application is a common strategy to control dodder in the field, but it is costly, ineffective, and further results in hazardous outcomes. Therefore, our study aims to identify the potential pathogens in naturally occurring dodder infections which may provide efficient biocontrol options. In this regard, the pathogens were isolated from the infected plants, their pathogenicity was validated through inoculation, and the optimal culture conditions for their growth were identified by determining the pathogenicity difference. The pathogenicity range was determined in vitro using the leaves of common horticultural plants and crops. Furthermore, a small range of horticultural plants parasitized by Cuscuta reflexa in the field were inoculated with the pathogen to determine their biosafety and biocontrol potential, and the pathogens were identified by morphological and molecular characterization. We found 7 strains that were isolated after pathogen enrichment culture. Among them, Cbp6 and Cbp7 showed the highest pathogenicity against C. reflexa. After testing the inoculation of more than 50 species of plants, only 9 species showed varying degrees of lesions on leaves, which proved the high biosafety for common plants. Field spraying of these pathogens showed a good control effect on C. reflexa after 21 days; the disease severityreached 66.0%, while its host plant did not display obvious symptoms. In conclusion, the pathogens Cbp6 and Cbp7 were identified as Alternaria alternata, and the results of this study provide a theoretical basis for the biological control of dodder. [ABSTRACT FROM AUTHOR]

Goat weed (Ageratum conyzoides L.) possesses several phytochemicals, which can be used environment friendly alternatives to synthetic chemical pesticides and herbicides. The major chemicals can serve as natural herbicides and pesticides to expand the range of the green biosphere. This paper: (i) overviews A. conyzoides L.; (ii) classification of A. conyzoides L.; (iii) botanical characteristics; (iv) invasiveness of A. conyzoides. (v) bioactivity of major compounds identified in Ageratum conyzoides L. and (vi) effects of A. conyzoides on different pathogens as biopesticide. [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]

Eritadenine from shiitake mushroom is a secondary metabolite with hypocholesterolemic, hypotensive and antiparasitic properties, thus promising for pharmaceutical and agricultural applications. Eritadenine is obtained from submerged mycelial cultures of shiitake, but the actual yields remain unsatisfactory to explore potential applications or industrial-scale production. In this study, green and blue LED lights were tested to increase yields of eritadenine in submerged cultures of shiitake. Notably, blue LEDs increased yields by 13–14 times, reaching 165.7 mg/L, compared to darkness (11.2 mg/L) and green light (12.1 mg/L) (p < 0.05, Tukey test). Nitrogen sources yeast extract (YE) and peptone (at 2 g/L) increased eritadenine production. YE promoted 22.6 mg/L, while peptone 18.3 mg/L. The recovery of eritadenine was evaluated using amberlite and activated charcoal (AC) adsorption isotherms. AC demonstrated the highest adsorption rate, with 75 mg of eritadenine per gram of AC, according to the Freundlich isotherm. The desorption rate reached 93.95% at pH 10. The extract obtained from submerged cultures had eritadenine content of 63.31%, corresponding to 87.86% of recovery, according to HPLC analysis. Furthermore, the novel bioherbicidal potential of eritadenine was tested on in vitro Chrysanthemum morifolium plants. The cultures extract containing eritadenine had a detrimental impact on plant development, generating mortality of 100% at 3%, 0.5%, and 0.25%. Moreover, pure eritadenine exhibited a phytotoxic effect similar than glyphosate on leaves, stems and roots. These findings highlight the significant bioherbicidal properties of eritadenine. Further studies are needed to understand the biosynthetic pathway of eritadenine and its bioherbicidal properties on weeds and illicit crops. [ABSTRACT FROM AUTHOR]

The challenge of managing invasive weed species continues to affect the agricultural industry, presenting ecological, economic, and agronomic hurdles that lead to over 100 billion USD in annual crop losses globally. One such concern is the management of Agrostis stolonifera L., commonly known as creeping bentgrass, particularly due to its ability to form hybrids. This scenario underscores the urgent need for innovative, effective, and environmentally sustainable herbicides, steering the focus toward natural substances as potential candidates. We report here a promising natural lactone, commonly known as menthalactone, which is derived from Mentha piperita L. Its phytotoxic activity was assessed against the monocot, bentgrass, and a dicot, lettuce (Lactuca sativa L.). Menthalactone displayed outstanding activity against bentgrass and was further evaluated for phytotoxic characteristics. The germination of A. stolonifera seeds was significantly inhibited with an IC50 value of 4.9 ± 1.2 µM. In contrast to bentgrass seeds, Lemna pausicostata L. plants were less responsive to menthalactone treatment, shown by an IC50 of 293.4 ± 70.6 µM. Both species are monocots, and the results suggest that menthalactone might have effects on seed germination but not on the metabolism of green tissues. The susceptibility of three common, obnoxious weed species, i.e., ryegrass (Lilium perenne), barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.), to menthalactone was assessed. Menthalactone at 1000 µM completely inhibited the germination of all three species of grasses, while 330 µM inhibited germination by less than 50%. The post-emergence application of menthalactone at 1% did not produce a significant inhibitory effect against ryegrass, barnyard grass, or crabgrass. [ABSTRACT FROM AUTHOR]

Weed management is crucial for successful rice cultivation. Bioherbicides derived from cogon grass extract offer a promising solution for weed control. Additionally, optimizing plant spacing has been recognized as an effective method to suppress weed growth. Thus, this study aims to investigate the impact of cogon grass extract application timing and plant spacing on weed growth in rice cultivation. The study was conducted from October 2022 to February 2023 in the Special Region of Yogyakarta, Indonesia. The study was 3 × 2 factorial and arranged in a randomized completely block design (RCBD). The first factor was the bioherbicide application timing: control (no application), three days before planting, and at the time of planting. The second factor was plant spacing: 15 × 15 and 25 × 25 cm. In total, there were six treatment combinations and three replications (replications as blocks). The research results indicated the application timing of bioherbicide did not significant effect on the growth of weed and rice, as well as the grain dry weight. Fimbristylis miliacea was obtained as the dominant weed species. Bioherbicide application at the time of planting could alter the composition of weed species compared to the control in plant spacing of 15 × 15 cm. Furthermore, the plant spacing of 25 × 25 cm resulted in higher grain and weed dry weight (19.40 g/clump and 45.00 g/0.25 m² ) compared to 15 × 15 cm (12.92 g/clump and 23.04 g/0.25 m² ). On the contrary, the grain dry weight per hectare was higher in 15 × 15 cm (5.74 t/ha) than in 25 × 25 cm (3.10 t/ha). The research findings indicate that closer plant spacing can suppress weed growth and increase the grain dry weight per hectare compared to wider plant spacing. We recommend that the use of cogon grass extract dosage needs to be increased above 50 L/ha. [ABSTRACT FROM AUTHOR]

Weeds are one of the biotic factors that cause crop productivity losses worldwide. Due to the consequences to human health and the environment of the indiscriminate use of synthetic herbicides, alternative methods involving the use of the allelopathy phenomenon have been gaining prominence. Here, we explore the allelopathic effect of Jatropha gossypiifolia L. on the weed Bidens bipinnata L. and investigate its potential herbicidal allelochemicals. In vitro bioassays demonstrated that the use of J. gossypiifolia leaf powder was able to inhibit seed germination and early growth of B. bipinnata seedlings, obtaining significant reductions with increasing concentration. Bioguided fractionation of the aqueous extract indicated that the hexane and ethyl acetate fractions were bioactive in inhibiting weed growth. Metabolomics based on mass spectrometry and molecular networks was used to annotate the allelochemicals of the bioactive fractions, generating the dereplication of metabolites from the classes of alkaloids, phenolics, fatty acids, steroids, and terpenoids, which may be associated with herbicidal activity. These results point to the allelopathic effect of the J. gossypiifolia leaf powder and its putative herbicide allelochemicals, providing subsidies for future studies on the application of this species in alternative weed management strategies. [ABSTRACT FROM AUTHOR]

Allelopathy, a biological phenomenon involving the production and release of secondary metabolites known as allelochemicals, plays a critical role in plant interactions and agroecosystem dynamics. Phenolic compounds are a significant class of allelochemicals that profoundly affect plant competition, soil health, and microbial communities. When released into the soil, their action depends on the soil's physico-chemical characteristics and microbial communities. This review comprehensively inspects phenolic allelochemicals’ structure-function relationship, their direct combat with root cells in the rhizosphere, ecological functions, and their role in plant succession and stress tolerance. Phenolic allelochemicals, characterized by their diverse structures and ecological roles, offer a sustainable alternative to synthetic herbicides due to their minimal residual impact on the environment and rapid biodegradation. Additionally, the review addresses the challenges and future directions in applying phenolic allelochemicals, aiming to bridge the gap between ecological theory and practical agricultural applications for environmental protection and crop productivity enhancement.

The challenge of managing invasive weed species continues to affect the agricultural industry, presenting ecological, economic, and agronomic hurdles that lead to over 100 billion USD in annual crop losses globally. One such concern is the management of Agrostis stolonifera L., commonly known as creeping bentgrass, particularly due to its ability to form hybrids. This scenario underscores the urgent need for innovative, effective, and environmentally sustainable herbicides, steering the focus toward natural substances as potential candidates. We report here a promising natural lactone, commonly known as menthalactone, which is derived from Mentha piperita L. Its phytotoxic activity was assessed against the monocot, bentgrass, and a dicot, lettuce (Lactuca sativa L.). Menthalactone displayed outstanding activity against bentgrass and was further evaluated for phytotoxic characteristics. The germination of A. stolonifera seeds was significantly inhibited with an IC50 value of 4.9 ± 1.2 µM. In contrast to bentgrass seeds, Lemna pausicostata L. plants were less responsive to menthalactone treatment, shown by an IC50 of 293.4 ± 70.6 µM. Both species are monocots, and the results suggest that menthalactone might have effects on seed germination but not on the metabolism of green tissues. The susceptibility of three common, obnoxious weed species, i.e., ryegrass (Lilium perenne), barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.), to menthalactone was assessed. Menthalactone at 1000 µM completely inhibited the germination of all three species of grasses, while 330 µM inhibited germination by less than 50%. The post-emergence application of menthalactone at 1% did not produce a significant inhibitory effect against ryegrass, barnyard grass, or crabgrass.

The fungus, Fusarium lateritium Nees ex Fr. (FL), has shown potential as a bioherbicide for velvetleaf (Abutilon theophrasti Medik.) control. However, to achieve optimal infection and weed mortality, bioherbicide applications must be applied to weeds that are in the cotyledonary growth stage, followed by a dew treatment of at least 16 h. Greenhouse and field experiments were established to discover possible synergistic disease interactions with a phenoxy herbicide to improve the bioherbicidal potential of this fungus, and to mitigate some of the physical and environmental restrictions that limit the utility of this fungus as a bioherbicide. In greenhouse experiments, mortalities of 94% and 94% were recorded from sequential applications of 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] (0.02 kg ae ha−1) followed by FL (1.5 × 106 spores ml−1) at 5 min or 7 days after herbicide treatment. Velvetleaf plants in the fifth-to-seventh leaf growth stage were infected and killed with < 8 hrs. of dew. Similar results occurred under field conditions. Infection and weed control were inhibited by tank mixtures of 2,4-DB and FL, and by sequential applications of FL followed by 2,4-DB. These results suggest that timely applications of 2,4-DB followed by F. lateritium may provide effective control of velvetleaf. [ABSTRACT FROM AUTHOR]

Synthetic chemical herbicides available to farmers and foresters are known to be hazardous, and their overuse, without possible alternatives, have resulted in some weed species developing resistance. Therefore, seaweed species were explored due to their known bioactive capability to see if they would potentially be effective as an alternative, novel bioherbicide. From a phytotoxic screen against Lactuca sativa (lettuce) seeds, the ethyl acetate extract of two Rhodophyta species, Mastocarpus stellatus (MEE) and Porphyra dioica (PEE) were found to be most active in reducing lettuce seedling growth. Through conducting pre- and post-plant emergence assays in lab trials, the phytotoxicities of both extracts were further evaluated against weed species: broad-leaf weed, Trifolium repens (white clover) and grass, Lolium multiflorum (Italian ryegrass). At 5 mg mL−1, MEE produced stronger pre-emergence phytotoxicities than PEE, significantly inhibiting seed germination and seedling growth of white clover by 77.3% and 97.2%, respectively, compared to the solvent control. For ryegrass seeds, comparing the phytotoxicities of both extracts to the solvent control, MEE inhibited germination and seedling growth by 30.2% and 66.8%, respectively, whereas PEE inhibited seedling growth by 21.1%, but had no inhibitory effect on germination. On the other hand, the post-emergence assay revealed stronger phytotoxic activities for PEE at the same concentration (5 mg mL−1). The overall growth of ryegrass and white clover plants, respectively, were reduced by 42.7% and 35.6%, due to PEE treatment, and 13.5% and 30.0%, due to MEE treatment, in comparison to the solvent control. MEE and PEE were found to contain significantly higher quantities of flavonoids compared to the more polar extracts of the same seaweeds, but it is unlikely that these mostly water-insoluble flavonoids played a major role in the observed phytotoxic effects. These findings are indicative of the presence of phytotoxins in MEE and PEE, and could possibly lead to the development of novel, greener and sustainable bioherbicide sources, to replace or augment synthetic herbicides. [ABSTRACT FROM AUTHOR]

Oregano essential oil (EO) is known as one of the EOs with the highest biological activity on target plant species. In this study, the inhibitory effects of different doses of oregano (Origanum onites L.) EO on the germination and seedling growth of some wheat cultivars and some problem weed species in wheat fields was investigated. For this purpose, both laboratory and pot experiments were carried out. Oregano EO obtained by steam distillation method and component analysis was made via GS/MS. Germination tests and pot experiments were carried out under controlled laboratory and greenhouse conditions. In the study, five wheat varieties, four for bread and one for durum, and five different weed species were used. The effects of different doses of oregano EO on the germination rate, viable plant rate, seedling length, and biomass of test plants were analyzed. According to the results, it was observed that oregano EO showed bioactivity on all species and cultivars included in the experiment. In terms of all parameters, it was concluded that wheat varieties showed higher resistance to oregano EO than weed species. These results show that oregano EO can be used to control some weed species that are a problem in wheat.

This study explores the bioconversion of diosgenin by Yarrowia lipolytica P01a, focusing on enhancing the antioxidant, antifungal, and herbicidal activities of the resulting extracts. The bioconversion process, involving glycosylation and hydroxylation, produced significant amounts of protodioscin and soyasaponin I. The extracts showed superior antioxidant activity, with up to 97.02% inhibition of ABTS· radicals and 33.30% inhibition of DPPH· radicals at 1000 mg L−1 of diosgenin. Antifungal assays revealed strong inhibitory effects against Botrytis cinerea, Alternaria sp., and Aspergillus niger, with maximum inhibition rates of 67.34%, 35.63%, and 65.53%, respectively. Additionally, the herbicidal activity of the bioconverted extracts was comparable to commercial herbicides, achieving 100% inhibition of seed germination in both monocotyledonous and dicotyledonous plants. These findings suggest that the Y. lipolytica P01a-mediated bioconversion of diosgenin could provide a sustainable and eco-friendly alternative for developing natural biofungicides and bioherbicides.

In the search for new alternative biocontrol strategies, phytopathogenic fungi could represent a new frontier for weed management. In this respect, as part of our ongoing work aiming at using fungal pathogens as an alternative to common herbicides, the foliar pathogen Nigrospora sphaerica has been evaluated to control buffelgrass (Cenchrus ciliaris). In particular, in this work, the isolation and structural elucidation of two new biosynthetically related metabolites, named nigrosphaeritriol (3-(hydroxymethyl)-2-methylpentane-1,4-diol) and nigrosphaerilactol (3-(1-hydroxyethyl)-4-methyltetrahydrofuran-2-ol), from the phytotoxic culture filtrate extract were described, along with the identification of several known metabolites. Moreover, the absolute stereochemistry of (3R,4S,5S)-nigrosphaerilactone, previously reported as (3S,4R,5R)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone, was determined for the first time by X-ray diffraction analysis. Considering their structural relationship, the determination of the absolute stereochemistry of nigrosphaerilactone allowed us to hypothesize the absolute stereochemistry of nigrosphaeritriol and nigrosphaerilactol. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tobacco mild green mosaic virus strain U2 (TMGMV‐U2) is a registered active ingredient in a bioherbicide to control tropical soda apple (TSA), Solanum viarum, an invasive weed. As required for registration, we developed empirical data on the host‐virus interaction and the virus's host range, survival, spread, and genomic sequence. RESULTS: TMGMV‐U2 killed TSA plants by causing systemic hypersensitive necrosis (SHN). It elicited local lesions in inoculated leaves which was followed by the plant's wilting and death. It moved from inoculated terminal leaves through the vasculature to roots and then to newly developed leaves. Phloem death was implicated in wilting and plant death. The SHN response was attenuated in plants grown at constant 32 °C. TMGMV‐U2 titer in TSA was low compared to a systemically susceptible tobacco. The virus remained infective for up to 6 months in infected dead TSA tissues and in soil in which infected plants had grown. Susceptible tobacco and pepper plants grown in soil that previously had infected dead TSA or in soil amended with the virus remained asymptomatic and virus‐free. A susceptible pepper crop grown in a field block following two consecutive crops of TMGMV‐U2‐infected susceptible tobacco grew disease‐free and virus‐free and without yield loss. Purified TMGMV‐U2 was infective for 1 year when stored at −20 °C or 5 °C and for 1 month at room temperature. No virus spread was found in the field. Genomic analyses confirmed the registered isolate to be a U2 strain and free of satellite TMV. The TMGMV‐U2‐susceptible species preponderantly belonged to the Solanaceae. A few hosts that were killed belonged to this family. Several new hosts to TMGMV‐U2 were found. These data enabled registration of TMGMV‐U2. CONCLUSION: TMGMV‐U2 can be used safely as a bioherbicide without risks to nontarget plants and the environment. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Weeds are among the most damaging pests of agriculture, causing ≈10% worldwide reduction in crop productivity each year. Over‐reliance on synthetic chemical herbicides has caused weeds around the world to evolve resistance. Bioherbicides may be an alternative. However, among their many constraints including strict environmental requirements, complicated mass‐production and high product costs, limited pathogenicity and a narrow spectrum of activity are frequently encountered and are major barriers to commercialization. RESULTS: We isolated a pathogenic fungus, HXDC‐1‐2, from diseased leaves of a gramineous weed, stiltgrass [Microstegium vimineum (Trin.) A. Camus], from the edge of farmland in Guizhou province, China. HXDC‐1‐2 was identified as the fungal species Bipolaris yamadae based on the morphological characteristics and ITS‐GPDH‐EF1α multiple primer analysis. Its potential as a bioherbicide was evaluated by determining its weed control efficacy and crop safety. The ED50 and ED90 values of HXDC‐1‐2 on Echinochloa crus‐galli were 3.22 × 103 and 1.32 × 105 conidia mL−1, respectively. Host range tests revealed that 20 gramineous weeds including Setaria viridis, Leptochloa chinensis, Eleusine indica, Pseudosorghum zollingeri, Leptochloa panicea, Bromus catharticus, E. crus‐galli plants, were extremely susceptible whereas 77 crop species from 27 plant families including rice, wheat, barley, corn, soybean and cotton (excluding cowpea and sorghum) were unaffected. CONCLUSION: Bipolaris yamadae strain HXDC‐1‐2 has great potential to be developed as a commercial broad‐spectrum bioherbicidal agent for controlling grass weeds in arable crops. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciências Agrárias is the property of Sociedade de Ciencias Agrarias de Portugal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Ciências Agrárias is the property of Sociedade de Ciencias Agrarias de Portugal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Pyrolysis is a thermochemical conversion process producing biochar, gas, and bio-oil at high temperatures in an oxygen-free environment. Specific pyrolysis conditions enable a significant production of the aqueous phase of bio-oil, commonly known as wood vinegar. Wood vinegar contains organic compounds such as acetic acid and phenols derived from bio-oil. These compounds have herbicidal properties against weeds and biostimulant properties for plant growth. This study reveals the potential for efficient management of cranberry residues consisting of stems and leaves by producing wood vinegar through pyrolysis at 475 °C with a humidity level of 20%. Membrane separation of wood vinegar, using nanofiltration (NF) and reverse osmosis (RO) membranes, yielded phenols in the retentate and acetic acid in the permeate with respective yields of 44.7% with NF membrane and 45% with RO membrane. Biostimulation tests using 2% of the retentate showed significant germination rates for basil, sage, and parsley plants. Additionally, using 40 mL of the wood vinegar permeate (30 mL injected at the base and 10 mL sprayed on the leaves) resulted in leaf damage, measured by conductivity (leakage of electrolytes released by the leaves), of 62.3% and 20.5% respectively for quack grass and white clover, two weeds found in cranberry production. [ABSTRACT FROM AUTHOR]

We characterized the chemical compounds present in the extract of dry leaves from Duranta erecta L. using ESI-MSn mass spectrometry and assessed their phytotoxic potential on Lactuca sativa L.. The extraction process involved exhaustive extraction with 50% ethanol, and the resulting extracts were subsequently dried through lyophilization. Solutions of 2.5, 5, 10, 20, and 40 mg/mL concentrations were prepared from the dried extracts to investigate their allelopathic effects on L. sativa, focusing on germination, germination speed, root elongation, shoot length, and fresh biomass. Statistical analysis was performed using Analysis of Variance, and means were compared using the Scott-Knott test (p < 0.05). The ESI-MSn analysis identified a total of 20 compounds in the extract, with 12 of them being reported for the first time in Duranta sp. Our findings suggest that D. erecta possesses allelopathic potential, as evidenced by its cytotoxicity, mitodepressive effects, and phytotoxicity on germination and morphological parameters in the bioassay conducted with L. sativa. [ABSTRACT FROM AUTHOR]

BACKGROUND: Many essential oils and their constituent volatile organic compounds are known to be phytotoxic and potential bioherbicides. This study aims to investigate the phytotoxicity of propenylbenzene‐rich essential oils and identify active molecule(s) therein. RESULTS: Five commercially available propenylbenzene‐rich oils were screened, of which betel (Piper betle L.) oil was identified as a potent natural phytotoxin. It dose‐dependently inhibited wheatgrass (Triticum aestivum) seed germination and growth in water and agar medium with half maximal inhibitory concentration (IC50) in the range 23.2–122.7 μg mL−1. Phytotoxicity‐guided fractionation and purification revealed chavibetol as the major and most potent phytotoxic constituent of betel oil, followed by chavibetol acetate. A structure–activity relationship study involving 12 propenylbenzenes indicated the structural and positional importance of aromatic substitutions for the activity. Furthermore, the phytotoxic efficacy of chavibetol was established against wheatgrass germination and growth in water (IC50 15.8–53.4 μg mL−1), agar (IC50 34.4–53.6 μg mL−1) and aerial (IC50 1.7–4.5 mg L−1) media with a more pronounced effect on the radicle. Also, in open phytojars, chavibetol efficiently inhibited the growth of 3–7‐day‐old bermudagrass (Cynodon dactylon) seedlings when sprayed directly (IC50 2.3–3.4 mg jar−1) or supplemented in agar (IC50 116.6–139.1 μg mL−1). The growth of pre‐germinated green amaranth (Amaranthus viridis) was inhibited more effectively in both application modes (1.2–1.4 mg jar−1 and IC50 26.8–31.4 μg mL−1 respectively). CONCLUSION: The study concluded betel oil as a potent phytotoxic herbal extract and its major constituent chavibetol as a promising volatile phytotoxin for the future management of weeds in their early phase of emergence. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Exploring the effects of chlorogenic acid (CA) can allow its use in the sustainable management of natural fiber-producing grass species. Herein, the pH-dependent effect of CA on germination and the physiological response in tall fescue (Festuca arundinacea) seeds in comparison to gibberellic acid (GA3) and fluridon (FD) was investigated. All CA treatments conferred significant reduction in germination index (GI), seed vigour, fresh seedling weight, coleoptile length, primary root length and root hairs compared to the control nutrient solution at pH 4. Above 2.82 mM CA, higher expression of total soluble protein, catalase and superoxide dismutase activities, lipid peroxidation, electrolyte leakage levels, and an induced prominent 28.4 KDa peptide were observed. CA (8.46 mM) significantly inhibited seed germination (50%, F = 4.56, P = 0.031, P < 0.05) at pH 4, and by contrast, conferred a strong stimulating effect at pH 6.8. The impact of pH on CA activity was significantly correlated to GI and percentage inhibitory and stimulatory effects (r = 0.96, p = 0.001). It is demonstrated that buffered CA differentially modified the expression of antioxidant enzymes activities and seed physiology thereby inhibiting seed germination at pH 4 compared to the herbicide FD (or the growth hormone) GA3. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are natural products widely used in sustainable agrochemistry, not only because they are biodegradable and safe but also because they are regarded as alternatives to chemical fungicides against fungal species that attack crops. Allelopathy, another field of study, falls within the most recent and sustainable strategies applied to weed suppression to replace synthetic herbicides. Therefore, this study reports the chemical composition and allelopathic and antifungal effects of the EOs extracted from Calyptranthes concinna dried leaves (Cc-EO) and its pure major constituent elemicin. Their antifungal activities were evaluated by the disk diffusion method (DDM) at doses between 0.05 mg/mL and 0.4 mg/mL of Cc-EO and elemicin. The allelopathic effect was evaluated by studying the inhibition of germination and the growth of Lactuca sativa seeds. The chemical composition of Cc-EO was determined by GC-MS and GC-FID analyses. The major constituents of Cc-EO were elemicin (60.5%), α-cadinol (9.0%) and caryophyllene oxide (8.3%). Cc-EO and elemicin were assayed in vitro against 17 fungi of agronomic interest (Aspergillus niger, A. flavus, A. nomius, Penicillium digitatum, P. expansum, Sclerotinia sclerotiorum, S. rolfsii, S. minor, Fusarium graminearum, Myrothecium verrucaria, Corynespora cassiicola, Erwinia psidii, Colletotrichum musae, Alternaria carthami, Rhizoctonia solani, Rhizopus stolonifer and Macrophomina phaseolina). The concentration of Cc-EO (0.4 mg/mL) inhibited 100% of the mycelium growth of seven strains, equal to the fungicide fluazinam, which was used as a positive control. Elemicin showed antifungal activity against all fungi at all concentrations under investigation (above 50%). A strong allelopathic effect was recorded for Cc-EO and elemicin at the dose of 0.28 mg/mL, with the almost total inhibition of germination. This study revealed, for the first time, the strong and remarkable fungicidal and allelopathic effects of Cc-EO and elemicin, an important finding for the agrochemical field.

Dodder (Cuscuta spp.) is a dangerous parasitic plant that causes serious damage to crop production and is challenging to eliminate. Herbicide application is a common strategy to control dodder in the field, but it is costly, ineffective, and further results in hazardous outcomes. Therefore, our study aims to identify the potential pathogens in naturally occurring dodder infections which may provide efficient biocontrol options. In this regard, the pathogens were isolated from the infected plants, their pathogenicity was validated through inoculation, and the optimal culture conditions for their growth were identified by determining the pathogenicity difference. The pathogenicity range was determined in vitro using the leaves of common horticultural plants and crops. Furthermore, a small range of horticultural plants parasitized by Cuscuta reflexa in the field were inoculated with the pathogen to determine their biosafety and biocontrol potential, and the pathogens were identified by morphological and molecular characterization. We found 7 strains that were isolated after pathogen enrichment culture. Among them, Cbp6 and Cbp7 showed the highest pathogenicity against C. reflexa. After testing the inoculation of more than 50 species of plants, only 9 species showed varying degrees of lesions on leaves, which proved the high biosafety for common plants. Field spraying of these pathogens showed a good control effect on C. reflexa after 21 days; the disease severityreached 66.0%, while its host plant did not display obvious symptoms. In conclusion, the pathogens Cbp6 and Cbp7 were identified as Alternaria alternata, and the results of this study provide a theoretical basis for the biological control of dodder.

Weeds cause significant agricultural losses worldwide, and herbicides have traditionally been the main solution to this problem. However, the extensive use of herbicides has led to multiple cases of weed resistance, which could generate an increase in the application concentration and consequently a higher persistence in the environment, hindering natural degradation processes. Consequently, more environmentally friendly alternatives, such as microbial bioherbicides, have been sought. Although these bioherbicides are promising, their efficacy remains a challenge, as evidenced by their limited commercial and industrial production. This article reviews the current status of microbial-based bioherbicides and highlights the potential of cell-free metabolites to improve their efficacy and commercial attractiveness. Stirred tank bioreactors are identified as the most widely used for production-scale submerged fermentation. In addition, the use of alternative carbon and nitrogen sources, such as industrial waste, supports the circular economy. Furthermore, this article discusses the optimization of downstream processes using bioprospecting and in silico technologies to identify target metabolites, which leads to more precise and efficient production strategies. Bacterial bioherbicides, particularly those derived from Pseudomonas and Xanthomonas, and fungal bioherbicides from genera such as Alternaria, Colletotrichum, Trichoderma and Phoma, show significant potential. Nevertheless, limitations such as their restricted range of action, their persistence in the environment, and regulatory issues restrict their commercial availability. The utilization of cell-free microbial metabolites is proposed as a promising solution due to their simpler handling and application. In addition, modern technologies, including encapsulation and integrated management with chemical herbicides, are investigated to enhance the efficacy and sustainability of bioherbicides.

ABSTRACT Cheatgrass (Bromus tectorum) is one of the most problematic invasive plants in the western United States. Invasion by annual grasses disrupts nutrient cycling and negatively affects above- and below-ground biodiversity. Land managers use chemical herbicides, mechanical controls, cultural practices, and bioherbicides to combat this invasive plant. Recently, the biocontrol agent Pseudomonas fluorescens D7 has been touted as a non-chemical herbicide that offers lasting control of cheatgrass. However, experimental results report limited effectiveness under field conditions. To understand the underlying cause of the variable efficacy of this commercially available bioherbicide, soil samples from an active cheatgrass invasion treated with P. fluorescens D7 were collected and screened using high-throughput sequencing. At 18 months post-application, the bioherbicide had limited lasting effects on bacterial community composition, and few reads assigned to P. fluorescens were found in our sequence data. We suggest that the failure to establish sufficiently may partially explain the inability of this biocontrol agent to suppress B. tectorum under field conditions. IMPORTANCE Cheatgrass is one of North America’s most problematic invasive species. Invasion by this annual grass alters ecosystem structure and function and has proven very challenging to remove with traditional approaches. Commercially available bioherbicides, like P. fluorescens D7, are applied with the goal of providing lasting control from a single application. However, experimental results suggest that this bioherbicide has limited efficacy under field conditions. Potential explanations for variable efficacy include a failure of this bioherbicide to establish in the soil microbiome. However, to our knowledge, no data exist to support or refute this hypothesis. Here, we use a deep-sequencing approach to better understand the effects of this bioherbicide on the soil microbiome and screen for P. fluorescens at 18 months post-application.

Calamus tenuis is a shrub species distributed across South Asia. It grows well in diversified habitats and tends to dominate plants in the surrounding environment. The phytotoxicity of C. tenuis and the action of its phytochemicals against other plant species could explain its dominant behavior. Compounds with phytotoxic activity are in high demand as prospective sources of ecofriendly bioherbicides. Therefore, we investigated the phytotoxicity of C. tenuis. Aqueous methanol extracts of this plant species significantly limited the growth of four test plant species, two monocots (barnyard grass and timothy), and two dicots (alfalfa and cress), in a dose- and species-dependent manner. Bio-directed chromatographic isolation of the C. tenuis extracts yielded two major active substances: a novel compound, calamulactone {(S)-methyl 8-(5-oxo-2,5-dihydrofuran-2-yl) octanoate}, and 3-oxo-α-ionone. Both of the identified compounds exerted strong growth inhibitory effects on cress and timothy seedlings. The concentrations of 3-oxo-α-ionone and calamulactone required to limit the growth of the cress seedlings by 50% (I50) were 281.6–199.5 and 141.1–105.5 µM, respectively, indicating that the effect of calamulactone was stronger with lower I50 values. Similarly, the seedlings of timothy also showed a considerably higher sensitivity to calamulactone (I50: 40.5–84.4 µM) than to 3-oxo-α-ionone (I50: 107.8–144.7 µM). The findings indicated that the leaves of C. tenuis have marked growth-inhibitory potential, and could affect surrounding plants to exert dominance over the surrounding plant community. Moreover, the two identified phytotoxic substances might play a key role in the phytotoxicity of C. tenuis, and could be a template for bioherbicide development. This paper was the first to report calamulactone and its phytotoxicity. [ABSTRACT FROM AUTHOR]

The present investigation aimed to develop inclusion complexes (ICs) from Psidium gaudichaudianum (GAU) essential oil (EO) and its major compound β-caryophyllene (β-CAR), and to evaluate their herbicidal (against Lolium multiflorum and Bidens pilosa) and cytogenotoxic (on Lactuca sativa) activities. The ICs were obtained using 2-hydroxypropyl-β-cyclodextrin (HPβCD) and they were prepared to avoid or reduce the volatility and degradation of GAU EO and β-CAR. The ICs obtained showed a complexation efficiency of 91.5 and 83.9% for GAU EO and β-CAR, respectively. The IC of GAU EO at a concentration of 3000 µg mL−1 displayed a significant effect against weed species B. pilosa and L. multiflorum. However, the β-CAR IC at a concentration of 3000 µg mL−1 was effective only on L. multiflorum. In addition, the cytogenotoxic activity evaluation revealed that there was a reduction in the mitotic index and an increase in chromosomal abnormalities. The produced ICs were able to protect the EO and β-CAR from volatility and degradation, with a high thermal stability, and they also enabled the solubilization of the EO and β-CAR in water without the addition of an organic solvent. Therefore, it is possible to indicate the obtained products as potential candidates for commercial exploration since the ICs allow the complexed EO to exhibit a more stable chemical constitution than pure EO under storage conditions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine in vitro the herbicidal effect of an essential oil of dill (Anethum graveolens) on germination and early seedling growth of two parasitic flowering plants in the genus Cuscuta (Cuscuta campestris and C. epithymum), as well as its phytotoxic impact on germination and early seedling growth of two host plants (alfalfa and red clover). Chemical analysis of the essential oil extracted from dill leaves and flowers showed that carvone (51.69%) and limonene (39.88%) predominated. The results of a seed bioassay showed inhibitory effects of different concentrations (1%, 0.5%, 0.1%, and 0.01% v v-1) of the essential oil of dill leaves on germination and early seedling growth of both tested species of the genus Cuscuta. Germination of C. campestris seeds was inhibited between 67% and 94%, while seed germination of C. epithymum was inhibited between 67% and 100%. A similar inhibitory effect was observed regarding the seedling length parameter. Moreover, the bioassay results indicated significant phytotoxic effects of dill essential oil on the seed germination and early seedling growth of host plants. Red clover proved more sensitive as even the lowest concentration inhibited germination by 35%, while higher concentrations caused 70-100% inhibition. On the other hand, lower concentations inhibited germination of alfalfa seeds by 5%, while higher concentrations caused greater inhibition (36-100%). Future research should include both pot experiments and field micro-trials to determine herbicidal, i.e. phytotoxic, effects of dill essential oil on parasitic flowering plants and cultivated species.

The capacity of extracellular self-DNA (esDNA) to inhibit growth is getting more research attention as this could be explored for several purposes, including the development of specific bioherbicides. While the inhibitory effect has been studied in several dicotyledon species, little is known about the effects and subsequent signaling processes in monocots. Here, we measured the growth, counted the number of lateral and crown roots, determined greenness index, quantified the production of O2.- and H2O2, and determined the expressions of genes encoding antioxidant enzymes (SODs and CATs) in rice (Oryza sativa L.), a model plant of monocots. After 7 d of germination, rice roots were exposed to 0, 75, and 150 µg cm-3 of esDNA. Inhibitory effect was found to be negatively correlated to esDNA concentration, as indicated by the length of primary roots. Interestingly, this negative effect was only observed in the directly exposed organ (root) but not in the length of shoot or fresh mass of the whole seedling. The percentage of greenness index of leaves and number of crown and lateral roots were also similar across treatments. However, esDNA exposure to root increased production of O2.- and H2O2 in the root. At the molecular level, the response was characterized by the decreased expression of the antioxidant genes SOD3, CATB, and CATC. These findings suggest that esDNA inhibits rice growth locally in, e.g. in treated roots, and the responses involve increased production of ROS and suppression of antioxidants. This study could be the basis for determining the combination of concentration and period of exposure that might significantly inhibit total growth of monocot weeds with a minimum effect on the crop.