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Pelargonic acid (PA) is a saturated fatty acid commonly found in several organisms, that is known for its phytotoxic effect and its use as bioherbicide for sustainable weed management. Although PA is already commercialised as bioherbicide, its molecular targets and mode of action is unknown according to the Herbicide Resistance Action Committee. Therefore, the aim of this work was focusing on the way this natural active substance impacts the plant metabolism of the model species Arabidopsis thaliana. PA caused increase of secondary and adventitious roots, as well as torsion, loss of gravitropism and phytotoxic effects. Moreover, PA altered the cellular arrangement and the PIN proteins activity. Computational simulations revealed that the intermolecular interactions between PA and the polar auxin transporter protein PIN1 are very similar to those established between the natural auxin IAA and PIN1. However, under intracellular conditions, the PA-PIN1 binding is more energetically stable than the IAA-PIN1. These results suggest that PA could act as an auxin-mimics bioherbicide. The exogenous application of PA would be responsible for the alterations observed both at structural and ultrastructural levels, which would be caused by the alteration on the transport of auxins into the plant, inducing root inhibition and ultimately total stop of root growth. • Pelargonic acid is a natural metabolite that can alter root architecture. • This specialised metabolite causes alterations in auxin distribution. • Pelargonic acid shares a binding site with IAA on the PIN1 protein. • The results suggest that PA could act as a bioherbicide by altering the auxin polar transport. [ABSTRACT FROM AUTHOR]

Sesquiterpene lactones (SL) are allelopathic compounds that demonstrate great potential of use in sustainable weed management. In this study, membrane processing technology was used for ethanolic Cynara cardunculus leaves extract (CcLE) ultra- and nanofiltration to produce SL-enriched fractions with increased phytotoxic activity. Experiments were conducted to select an ultrafiltration membrane (DuraMem500, DuraMem900 and SuezGH2000) for SL recovery and high molecular weight compounds (MWC) removal. SuezGH2000, which had rejection percentage of 50 % and 88 % for cynaropicrin (Cyn) and chlorophyll, respectively, was used for a sequential purification along with DuraMem200 for lower MWC removal. Since Cyn content on initial feed (11.9 %) and permeate (11.2 %) were similar, as well as phytotoxic activity, the results suggested that DuraMem200 was unsuitable for CcLE fractionation. SuezGH2000 revealed a slight increase on SL content, so, the permeation profile and enhancement of SL content were evaluated. An increase on SL content (36.0–71.0 %) was obtained after 2.3 diavolumes, followed by a decrease between 2.6 and 4.7 diavolumes. Phytotoxic activity evaluations revealed a direct association with SL content with enhancement of activity, particularly at inhibiting shoot growth of Portulaca oleracea. This study revealed SuezGH2000 effectiveness on SL purity improvement on CcLE fractions after 2.3 diavolumes and its potential to be used as a bioherbicide active component. • Enriched fractions were obtained through membrane processing technology. • Suez™GH showed better separation between cynaropicrin and chlorophylls. • Suez™GH enhanced sesquiterpene lactones content from 36 % to 71 %. • Enriched fractions showed enhanced phytotoxic activity against Portulaca oleracea. [ABSTRACT FROM AUTHOR]

Pseudomonads are well-known for their plant growth-promoting properties and biocontrol capabilities against microbial pathogens. Recently, their potential to protect crops from parasitic plants has garnered attention. This study investigates the potential of different Pseudomonas strains to inhibit broomrape growth and to protect host plants against weed infestation. Four Pseudomonas strains, two P. fluorescens JV391D17 and JV391D10, one P. chlororaphis JV395B and one P. ogarae F113 were cultivated using various carbon sources, including fructose, pyruvate, fumarate, and malate, to enhance the diversity of potential Orobanche growth inhibition (OGI)-specialized metabolites produced by Pseudomonas strains. Both global and targeted metabolomic approaches were utilized to identify specific OGI metabolites. Both carbon sources and Pseudomonas genetic diversity significantly influenced the production of OGI metabolites. P. chlororaphis JV395B and P. ogarae F113 produced unique OGI metabolites belonging to different chemical families, such as hydroxyphenazines and phloroglucinol compounds, respectively. Additionally, metabolomic analyses identified an unannotated potential OGI ion, M375T65. This ion was produced by all Pseudomonas strains but was found to be over-accumulated in JV395B, which likely explains its superior OGI activity. Then, greenhouse experiments were performed to evaluate the biocontrol efficacy of selected strains: they showed the efficacy of these strains, particularly JV395B, in reducing broomrape infestation in rapeseed. These findings suggest that certain Pseudomonas strains, through their metabolite production, can offer a sustainable biocontrol strategy against parasitic plants. This biocontrol activity can be optimized by environmental factors, such as carbon amendments. Ultimately, this approach presents a promising alternative to chemical herbicides. • Pseudomonads boost plants by Orobanche growth inhibition (OGI) metabolite production. • OGI metabolites in Pseudomonas vary with carbon sources and genetic diversity. • Pseudomonas strains with OGI metabolites reduce broomrape in greenhouse tests. • OGI production can be optimized by strain selection or specific carbon sources. [ABSTRACT FROM AUTHOR]

Harmaline is an indole alkaloid with demonstrated phytotoxicity and recognized pharmacological applications. However, no information is available concerning its mode of action on plant metabolism. Therefore, the present work evaluated bioherbicide mode of action of harmaline on plant metabolism of Arabidopsis thaliana (L.) Heynh. Harmaline induced a strong inhibitory activity on root growth of treated seedlings, reaching IC 50 and IC 80 values of 14 and 29 μM, respectively. Treated roots were shorter and thicker than control and were characterized by a shorter root meristem size and an increase of root hairs production. Harmaline induced ultrastructural changes such as increment of cell wall thickness, higher density and condensation of mitochondria and vacuolization, appearance of cell wall deposits, increment of Golgi secretory activity and higher percentage of aberrant nuclei. The ethylene inhibitor AgNO 3 reversed high root hair appearance and increment of root thickness, and pTCSn::GFP transgenic line showed fluorescence cytokinin signal in stele zone after harmaline treatment that was absent in control, whereas the auxin signal in the transgenic line DR5 was significantly reduced by the treatment. All these results suggest that the mode of action of harmaline could be involving auxin, ethylene and cytokinin synergic/antagonistic action. • Harmaline showed phytotoxic potential on Arabidopsis thaliana seedlings. • Harmaline induced ultrastructural changes on Arabidopsis thaliana roots. • Cytokinin, auxin and ethylene could be involved in harmaline mode of action. [ABSTRACT FROM AUTHOR]

Since the increasing prevalence of herbicide-resistant weeds and herbicide bans, the use of biological controls with mycoherbicides become an innovative approach of weed control. In this study, we verified the pathogenicity of Phoma multirostrata TBRC 12769 against the common weed in Thailand, tridax daisy (Tridax procumbens), with its mechanism of infection unveiled by fluorescence microscopy. P. multirostrata directly penetrated through epidermal cells, stomata, and trichomes at 48 h post-inoculation. The hyphae also propagated in the lumen of the trichome, enabling the fungus to grow subcuticular to neighboring weed tissues at the bases of leaf trichomes. The necrotic pattern emerged around the trichome. During necrosis, unicellular chlamydospores were also detected inside the leaf trichomes, suggesting an overwintering stage under stress and nutrient-depleting conditions. Trichomes of weed leaves were found to be key infection sites for pathogenesis. Topical application of conidial suspension on T. procumbens potted plants led to 60–98% and 65 and 87% disease incidence under laboratory and greenhouse conditions, respectively, on days 15–20 post-inoculation. The 16-h dew period incubation results in a sharp increase by 37% in the pathogenicity rate. The greenhouse trials verified that the fungus is non-pathogenic to eight crops. Our LC-MS analysis indicated that norharman, a known bioherbicidal compound, and other compounds were detected in the supernatant fraction of fungal culture, of which resulted in a blight symptom on T. procumbens leaves. This study demonstrated that the P. multirostrata isolate is an effective mycoherbicide for this broadleaf weed. • A Phoma multirostrata isolate is a potential myco-herbicide for controlling Tridax procumbens. • The fungus showed no pathogenicity against eight important crops in Thailand. • The weed pathogenesis is mediated by infection through stomata and trichomes and direct penetration of the epidermis. • Fungal inoculation with a dew period markedly accelerated the infection of the weed. [ABSTRACT FROM AUTHOR]

• Thirty-three metabolites were identified by UHPLC-MS/MS analysis. • A possible correlation was observed between flavonoids and allelopathy. • This is the first study for allelopathic activity in Lonchocarpus cultratus. • The phytotoxic effect may occur due to synergistic action. Lonchocarpus cultratus (Vell.) A.M.G. Azevedo & H.C. Lima (Fabaceae) is a native tree species and from which flavonoids, triterpenes, alkaloid were isolated. In addition, potent antiproliferative activity of hexane fraction and chalcone, obtained from this plant, has been described in different cell lines of human tumors. However, no studies were found on the allelopathic and/or bioherbicidal action, using aerial parts of L. cultratus. Thus, the aim of the present work was to evaluate the allelopathic activity of methanol extract, fractions and compounds from aerial parts of L. cultratus. Dried aerial parts were extracted by exhausting extraction with methanol at room temperature, and the solvent was evaporated under reduced pressure providing the crude extract. The crude extract was partitioned in a liquid-liquid extraction and to obtain hexanic (HF), chloroform (CF), ethyl acetate (EAF), and hydromethanolic (HMF) fractions. The compounds were extracted from fractions through chromatographic methods. Crude extract and its fractions inhibited Lactuca sativa germination mean time (GMT) and germination speed índex (GSI), but not the germination percentage (GP) of Lactuca sativa. Crude extract and hexane fraction inhibited the hypocotyl growth of L. sativa seedlings and the other fractions inhibited the primary root of seedlings. Hexane, chloroform, and ethyl acetate fractions inhibited primary root growth of Euphorbia heterophylla. Chalcone 2',4'-dihydroxy-5'-prenylchalcone, flavanone 8-prenylpinocembrin and alkaloid 4-hydroxy-N-methylproline were tested on lettuce early growth. Thirty-three metabolites were identified by UHPLC-MS/MS analysis, with flavonoid derivatives being the most abundant constituents. [ABSTRACT FROM AUTHOR]

The need to reduce the use of chemical pesticides currently fosters great interest in eco-friendly biological control agents. In addition, the isolation of plant allelopathic substances and the evaluation of their phytotoxic effects can lead to the discovery of new natural herbicides. In this context, our study aimed to assess the herbicidal activity of ten crude extracts obtained from aerial parts of Tunisian spontaneous plants against Trifolium incarnatum, Silybum marianum and Phalaris minor. It confirmed that the Cynara cardunculus methanolic extract best inhibited weed germination and seedling growth, and caused necrosis or chlorosis. Following a bioassay-guided fractionation, five main phenolic compounds, (1) syringic acid, (2) p -coumaric acid, (3) myricitrin, (4) quercetin and (5) naringenin were identified in the most active crude methanolic extract. Then, only 3 of the flavonoids contained in the most active fraction were tested on Trifolium incarnatum. The 3 compounds had a significant phytotoxic effect and therefore could be employed in a new composition of botanical herbicides to control crop weeds. Besides, a novel herbicide composition was designed to improve the post-emergence activity of the methanolic extract. The formulation containing the C. cardunculus crude methanolic extract showed the same herbicidal activity as the standard industrial bioherbicide containing pelargonic acid. These results make C. cardunculus a suitable source of natural compounds potentially usable as natural herbicides. Image, graphical abstract • C. cardunculus extract had the best herbicidal activity among 10 plant extracts. • Five phenolic compounds were identified in C. cardunculus. • Myricitrin, naringenin and quercetin were the main active compounds in C. cardunculus. • Fraction 2 of C. cardunculus had the same herbicidal effect as biological herbicide. [ABSTRACT FROM AUTHOR]

The potentiality of Phoma sp. inactive fungal biomass, waste from the bioherbicide production, was evaluated for the treatment of colored effluents containing Acid Red 18 (AR 18) dye. The batch experiments were performed to evaluate the following parameters: pH of the solution (2–10), dye concentration (50–200 mg L−1), adsorbent dose (0.5–2.5 g L−1), contact time (0–180 min) and temperature (298–328 K). The batch experiments using a synthetic dye solution revealed that Phoma sp. was efficient at pH of 2.0, 298 K and using a dosage of 1.25 g L−1. The process was fast, being the equilibrium reached within 180 min. The maximum value of biosorption capacity was 63.58 mg g−1, being the process favorable and exothermic. From the fixed bed assays, breakthrough curves were obtained, presenting a mass transfer zone of 7.08 cm and breakthrough time of 443 min. Phoma sp. was efficient to decolorize a simulated effluent, removing more than 90% of the color. From the obtained results, it can be concluded that Phoma sp. inactive biomass is a low–cost option to treat colored effluents in continuous and discontinuous biosorption modes. These indicate that Phoma sp. of inactive biomass is an option for the treatment of colored effluents. Image 1 • Phoma sp., a waste from the bioherbicide production, was evaluated as a new biosorbent options. • Phoma sp. waste was able to treat colored effluents in batch and fixed bed systems. • Phoma sp. was efficient to treat a simulated effluent, reaching 90% of color removal. [ABSTRACT FROM AUTHOR]

Six different furanocoumarins were isolated from the aerial parts of Ducrosia anethifolia and tested in vitro for plant cell elongation in etiolated wheat coleoptile. They were also tested for their ability to control three different weeds: ribwort plantain, annual ryegrass, and common purslane. These compounds exhibited strong inhibition of plant cell elongation. In the case of (+)-heraclenin, the IC 50 was lower than 20 μM, indicating a better inhibition than the positive control Logran®. Computational experiments for docking and molecular dynamics revealed for the investigated furanocoumarins bearing an epoxide moiety an improved fitting and stronger interaction with the auxin-like TIR1 ubiquitin ligase. Furthermore, the formed inhibition complex remained also stable during dynamic evaluation. Bidental interaction at the active site, along with an extended hydrogen-bond lifetime, explained the enhanced activity of the epoxides. The in vitro weed bioassay results showed that Plantago lanceolata was the most affected weed for germination, root, and shoot development. In addition, (+)-heraclenin displayed better inhibition values than positive control even at 300 μM concentration. Six furanocoumarins have been isolated from Ducrosia anethifolia , which inhibit plant cell elongation in etiolated wheat coleoptile and the germination, root, and shoot development of eudicotyledonous weeds, such as Plantago lanceolata, which infect cereal and legume crops. [Display omitted] • Six different furanocoumarins have been isolated from Ducrosia anethifolia. • Those allelochemicals are more phytotoxic than commercial herbicide Logran®. • Furanocoumarins seems to act as auxin-like TIR ubiquitin ligase inhibitors in plants. • Ribwort plantain was the most affected in terms of germination, root and shoot formation. • Furanocoumarin epoxide derivatives are the best option for weed control. [ABSTRACT FROM AUTHOR]

Allelopathy, the inhibition of neighbouring plant growth by certain plants, can be particularly useful if applied in a targeted way for weed management. So, this study aimed to assess and characterize the herbicidal activity of fresh and dried leaves from young Eucalyptus globulus Labill. trees applied as a soil amendment. For this, fresh and dried leaves (FL and DL, respectively) were incorporated into the soil at different concentrations (0, 1, 5, and 10% w/w), where Portulaca oleracea L. seeds were sown. After 5 weeks of exposure, results revealed that the soil incorporation of DL at 10% (w/w) presented the strongest herbicidal properties, inhibiting seed germination by 63% and inducing the loss of cell viability. To unravel the possible mode of action and the main targets at both cellular and subcellular levels, an in vitro experiment was performed. Purslane seeds were sown in a nutritive medium containing different dilutions of an aqueous extract prepared with dried eucalyptus leaves. After 5 days of exposure, germinated seedlings were processed for transmission electron microscopy and histological analyses as well as for reactive oxygen species (ROS) in vivo detection by confocal laser scanning microscopy. Results revealed that the allelochemical release from DL induced ROS overproduction, resulting in the loss of cell integrity and organization, which was characterized by damage to several cellular sub-structures, along with enhanced accumulation of lipid droplets. Overall, the incorporation of DL into the soil can represent a sustainable alternative to reduce synthetic herbicide application and subsequent environmental contamination. • Dried leaves of young E. globulus had the greatest pre-emergent herbicidal activity. • Allelochemicals caused redox disorders in purslane cotyledons and radicles. • Phytochemicals induced the loss of cell organization and integrity. • Dried leaf soil incorporation can represent an alternative for weed control. [ABSTRACT FROM AUTHOR]

Weeds are one of the main problems faced by horticulturists, which are responsible for significant losses in many vegetable crops. The utilization of microbial bioproducts are an efficient alternative to weeds control. Aiming at replacing synthetic herbicides by bioherbicides and looking for strategies which are less aggressive to the environment, this work provides a bioproduct formulated with metabolites produced by Phoma sp. with herbicidal activity against bioindicated species of plants and weeds. Formulations containing a cells-free or spores-free culture filtrate, palm oil, Span® 80 and Tween® 80 were evaluated in order to increase the phytotoxicity. The best formulation contained 2.8% (w/v) surfactant (Span® 80 and Tween® 80), 8.2% (w/v) oil concentration and hydrophilic-lipophilic balance of 12.8. Combining adjuvants with culture filtrate of Phoma sp. showed phytotoxic efficiency against Bidens pilosa , Amaranthus retroflexus and Conyza canadensis . [ABSTRACT FROM AUTHOR]

This study presents the isolation and identification of a fungus ( Fusarium fujikuroi ) from the Brazilian Pampa biome that is able to produce phytotoxic secondary metabolites with herbicidal activity. Before selecting such promising fungus, 132 microorganisms were isolated from weed plants with infections symptoms. Each sample of isolated material was used in submerged fermentation to produce a fermented broth. Thereafter, the cells were separated by centrifugation and the supernatant was filtered. Each filtered sample (culture filtrate) was used to evaluate the herbicidal activity in the bioassays with two target plants: Cucumis sativus and Sorghum bicolor . The selection criteria consisted of analyzing germination in pre-emergence, phytotoxicity, plant height and root length in post-emergence, and lesions in detached leaf-punctured assay. The pre-emergence was the primary screening, where 11 samples of culture filtrate provided 100% inhibition of germination of both plants. These samples underwent a secondary screening, which the sample SO210 presented 25% phytotoxicity, 40% reduction of plant height, 28% reduction of root length, and necrosis and chlorosis in 70% of foliar area. The microorganism coded as SO210 was identified as a strain of Fusarium fujikuroi . Up to now, studies that attribute herbicidal activity to this fungus are scarce in the literature. Therefore, this work shows a potential activity of metabolites produced by this fungus toward the inhibition of germination and development of plant weeds. [ABSTRACT FROM AUTHOR]

This work investigated the effect of variably formulated pesta granules containing wild and UV mutated Pseudomonas aeruginosa and Lasiodiplodia pseudotheobromae on the rate of CO 2 evolution, organic carbon content, enzymatic activity (acidic and alkaline phosphatase, dehydrogenases, urease and protease) and representative soil microorganisms in the soils using different assay techniques. After the 35th day period of experiment, the pesta granule formulation BH4 showed the best evolution of CO 2 (824 ± 6.2 mg CO 2 kg −1 soil hr −1 ) as against control treatment (689 ± 3.7 mg CO 2 kg −1 soil hr −1 ). Enzymes activities, organic carbon content of 3.8% on the 15th day of study and stable representation of microorganisms that include actinomycetes, fungi, heterogenous as well as soil nitrogen-mediatory bacteria were equally at their maximum level BH4 treatments. The phytotoxic assay showed no inhibitory effect on Solanum lycopersicum seeds and seedlings compared to the observed growth inhibition on the tested weeds ( Amaranthus hybridus and Echinocholoa crus - galli ) which corresponds with positive control glyphosate treatment. The glyphosate treated soil had the least critical results on parameters investigated during the study. The order of bioherbicidal activity is BH4>BH2>BH6>BH3>BH1>BH5>positive control. Results from this study confirmed the target efficacy of variably formulated pesta granules which is sustainable, cheap, ecologically suitable and recent. This is in addition to recognizing the microbial-derived formulations as characteristically potent alternative to chemical herbicides utility in agrosystems practice. Further study of the underlining factor responsible for the bioherbicidal performances of the variably formulated pesta granules and field trials are critical for their future commercialization. [ABSTRACT FROM AUTHOR]

In certain plant species, essential oils have been reported to inhibit seed germination and cause toxicity and have been associated with a loss of photosynthetic activity. This study aimed to evaluate the effects of essential oils and their major compound citronellal on the germination and growth of crabgrass ( Digitaria horizontalis ) and burrgrass ( Cenchrus echinatus ). Essential oils from E. citriodora and C. nardus and pure citronellal compound were used at concentrations of 1% and 10% and 20% to test seed germination and phytotoxic effects, respectively, in the plants. The treatments application was done when the plants were at the four-leaf stage. Seed germination was reduced drastically (97–99% reduction relative to untreated controls), with citronellal showing more drastic reductions than essential oils. In addition, evaluated the phytotoxic effects of essential oils on plant height and dry mass of shoots and roots were evaluated. The negative effects of the oils were seen 12 h following the treatment. The application of the oils at a concentration of 20% reduced the accumulation of dry mass of shoots and roots; however, the number of tiller only affected stomatal opening in burrgrass. Finally, the oils reduced chlorophyll and total protein content in the weeds by more than 80% and 90%, respectively. Therefore, these oils may have application as potential bioherbicides to controlling weeds. [ABSTRACT FROM AUTHOR]

Essential oils are natural products capable of being used as novel agrochemical products. In order to fill knowledge gaps, this work evaluates the bioherbicidal potential of Schinus terebinthifolia fruit essential oil (EOsST) emulsions on germination parameters of Lactuca sativa and Urochloa brizantha seeds. The hydrodynamic size distribution of the emulsions was evaluated by dynamic light scattering (DLS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). Also, the chemical composition of EOsST was performed by gas chromatography coupled to mass spectrometry (GC-MS). DLS results suggest nanoemulsion (NE) particle sizes smaller than 735 nm and SEM images showed spherical and cuboid shapes. FTIR spectra indicate peaks at 1640 cm−1 and 1440 cm−1, referring to the benzene ring, and the C–H stretching band from 2970 cm−1–2870 cm−1 indicates the interaction between EOsST and TX-100. GC-MS reveals that the major compounds present on EOsST were α-pinene, germacrene-D, and β-pinene. U. brizantha seed germination was reduced at doses >2 mg mL−1 and completely inhibited at 32 mg mL−1. For L. sativa there was a reduction in germination which was dose-dependent and no dose caused total inhibition. Moreover, a decrease in photosynthetic pigments, flavonoids, phenolics, and total tannins was observed. Enzyme activity was altered, with reduction to catalase and peroxidase. [Display omitted] • Pre-emergent bioherbicidal activity of Schinus terebinthifolia Raddi essential oil was evaluated. • Morphophysiological damages were studied. • The photosynthetic pigments were strongly influenced by their presence in the nanoemulsion. • The enzymatic activity demonstrated the mode of action of the nanoemulsions. [ABSTRACT FROM AUTHOR]

The bioherbicidal fungus Phoma macrostoma produces macrocidins, which induce chlorosis in susceptible plant species by interfering with the carotenoid biosynthesis. Macrocidins inhibit the enzyme phytoene desaturase (PDS) and likely act on other components of the carotenoid biosynthetic pathway. It was hypothesized that macrocidins’ mode(s) of action differ between susceptible plant species that respond differently to these phytotoxins. This idea was tested by exploring the impact of macrocidins on the carotenoid and carotenoid precursor profiles over time, as well as chlorophyll fluorescence parameters, symptom severity and biomass, in dandelions, groundsel and chickpea. While PDS was inhibited in all three plants, this impact was strongest in dandelion and weakest in groundsel. However, groundsel showed the most severe macrocidin-induced symptoms and biomass reduction. In solution, macrocidin A bound iron and magnesium cations. Macrocidin‐induced changes in OJIP chlorophyll fluorescence parameters are consistent with inhibited electron transfer from Q A to Q B (potentially due to iron-binding), and uncoupling the light-harvesting complex (LHC) of photosystem II (PSII) from the reaction centre, leading to an increase in photoprotective xanthophylls. This latter impact was stronger in groundsel than chickpea or dandelion. The decrease in total carotenoid and carotenoid precursor content in macrocidin-treated plants could be explained by macrocidins’ magnesium-binding activity reducing the efficiency of 1‐deoxy‐D‐xylulose (DXP) reductoisomerase (DXR) and/or phytoene synthase (PSY). The putatively metal‐binding‐related modes of action of macrocidins occurred more rapidly than inhibition of PDS. These inter‐specific variations in, and diversity of, modes of action suggest that the risk of resistance developing to macrocidins is very low. [ABSTRACT FROM AUTHOR]

[Display omitted] • The investigation of the bioactive effects of chamomile bioactive on weed is the first report. • Chamomile can be cultivated as a pre-planting in chamomile-wheat rotation. • Chamomile can be introduced as a viable candidate for the production of bioherbicide. • Chamomile allelochemicals has suppressive effects on weeds both at the cellular up to organ levels. Intensive chemical herbicide use has resulted in human health and environmental issues. This study evaluated the phytotoxic potential of chamomile extract as a bioherbicide to minimize chemical herbicide use in wheat production. Treatments including four concentrations (0, 50, 100, and 150 mL/L) of three different chamomile plant parts (root, shoot, and root + shoot) extracts were applied to flixweed as a major weed in wheat production. Except for 50 mL/L of root extract, other concentrations of chamomile extracts decreased the germination rate of flixweed. Germnaiton rate of wheat increased with chamomile extracts except at 150 mL/L concentration of shoot extract at which the germination rate of flixweed and wheat reduced by 71.7 and 35.4%, respectively, compared to respective controls. Compared to wheat, malondialdehyde and proline in flixweed were increased fivefold in flixweed and compared to the control, ranged from 84–473 and 240–1422%, respectively. Chamomile extract also declined cell viability much quicker in flixweed than in wheat reflecting on greater inhibitory effect for flixweed control. Chamomile shoot extract reduced seedling weight and vigor index of flixweed by 63.75 and 59.4%, respectively, compared to the respective control. Results of liquid chromatography mass spectrometry of chamomile extract indicated polyphenols, flavonoids, terpenoids, and bioactive phenolic coumarins, glycosylated derivatives, quercetin and its derivatives, herniarin, umbelliferone, P-cymene, chamazulene, farnesol, amitrole, 1,8-cineole, and limonene were effective in inhibiting the germination and growth of flixweed. We concluded that 150 mg/L of chamomile shoot extract could be used as a bioherbicide to sustainably suppress flixweed in wheat production. [ABSTRACT FROM AUTHOR]

In this study was presented a rational strategy to scale-up a wild fungal strain from the Brazilian Pampa biome to produce compounds with herbicidal activity in pre-emergence. It was defined the medium composition for the growth and production of bioherbicide in shaken flasks using sucrose corn steep liquor as substrate. In a second step, the process variables in a stirred-tank bioreactor were assessed. Maximum biomass production in shaken flasks was 23.87 g L −1 (41% higher than synthetic media) and in the bioreator 27.8 g L −1 . The Diaporthe sp. growth in bioreactor was negatively affected by agitation higher than 40 rpm. The bioherbicide efficiency rate reached 100%, since none seed germinated after the application of fermented broth. The Brazilian Pampa biome could be an effective way to obtain high-value products from the biodiversity. [ABSTRACT FROM AUTHOR]

Plant-based phytotoxins play an important role in plant-plant interaction and are of great promise for the development of bioherbicide. In this study, screening of essential oils from six different Curcuma rhizomes identified black turmeric (Curcuma caesia Roxb.) oil as an efficient growth inhibitor in wheatgrass coleoptile bioassay (IC 50 57.1 µg/mL). The phytotoxic efficacy of this oil was further confirmed through the dose dependent (10.0–300.0 µg/mL) inhibition of germination, coleoptile and radicle growth of wheatgrass seeds in water medium (IC 50 176.7, 90.6 and 93.0 µg/mL respectively) and the pre-germinated seeds in agar medium. Activity-guided fractionation and purification of the crude oil identified curzerenone, a major furanosesquiterpene in this oil as the most active phytotoxin (IC 50 13.0 µg/mL in coleoptile bioassay; 188.3, 34.7 and 36.7 µg/mL respectively in water medium). Structure-activity relationship study indicated the importance of all the functional groups for its phytotoxicity. A significant contribution by the oxygenated monoterpenes towards oil phytotoxicity was also evidenced. Though inhibitory efficacy of the oil was comparatively weak in soil, a profound activity through aerial diffusion was observed against germination and/or growth of fresh and pre-germinated wheatgrass seeds (IC 50 1.4–6.2 mg/L air). The study also confirmed the uptake of active phytotoxins with no detectable transformation by the seeds in water and their persistence in the soil for at least one and half months. Further, its applicability was demonstrated through an efficient post-emergence growth inhibition (IC 50 37.0–81.4 µg/mL) of bermudagrass weed in water and agar medium. [Display omitted] • Screening: black turmeric (Curcuma caesia) essential oil is a potent phytotoxin. • Major phytotoxins: curzerenone (a furanosesquiterpene) and oxygenated monoterpenes. • Modes of transport: water, agar, soil and aerial diffusion. • Uptake of active phytotoxins by the seeds with no detectable transformation. • Efficient inhibitor of post-emergence growth in bermudagrass weed. [ABSTRACT FROM AUTHOR]

Abstract: Trichothecenes, a major class of mycotoxins produced by Fusarium, Myrothecium, and Stachybotrys species, are toxic to both plants and mammals. Simple trichothecenes, including type A (e.g., T-2 toxin) and type B (e.g., deoxynivalenol), are generally less toxic than macrocyclic trichothecenes. We sought to determine if simple trichothecenes are a potential source of candidates for development as bioherbicides, which require high phytotoxicity and low mammalian toxicity. We examined 28 simple trichothecenes in vitro for phytotoxicity using a small aquatic plant, Lemna pausicostata, and for mammalian toxicity using four cultured mammalian cell lines. Several structure–activity relationships were identified, including the following two, which may be relevant to bioherbicide development: peracetylation of type B trichothecenes and de-epoxidation of type A trichothecenes both substantially reduced mammalian toxicity with little effect on phytotoxicity. It was concluded that simple trichothecenes possessing strong phytotoxicity and minimal mammalian toxicity in vitro can be identified. [Copyright &y& Elsevier]

Abstract: The essential oil of Chrysanthemum coronarium (Garland) flowerheads was analyzed by gas chromatography–mass spectrometry and essayed for its in vitro scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and its antimicrobial activities against Escherichia coli, Salmonella typhymurium, Candida albicans, Bacillus cereus and Staphylococcus aureus. The aqueous extracts were tested for their allelopathic properties on seed germination and seedling growth of two annual weeds (Sinapis arvensis and Phalaris canariensis) and two crops (Triticum durum and Zea mays) and the identity of the phenolic components was determined by using HPLC–PDA-MS. A total of 40 components, representing 96.58% of the total oil were identified, and the most plentiful constituents were found to be cis-chrysanthenyl acetate (21.82%), trans-chrysanthenyl acetate (12.78%), (E)-β-farnesene (8.97%), germacrene-D (8.92%) and camphor (6.03%). The oil was unable to reduce the DPPH radical, while it exhibited a good antimicrobial activity against the gram-positive bacteria B. aereus and S. aureus. The aqueous extracts suppress the germination and reduce the seedling growth of the target species. The phytotoxic effect was found to be selective towards weeds with the effects being more pronounced in S. arvensis and P. canariensis. HPLC–PDA-MS analysis allowed the identification of chlorogenic acid acid, di-cafeoylquinic acids isomers, rutin, luteolin, luteolin-7-O-glucoside, myricetin-3-O-galactoside and tricin. The latter components were reported in C. coronarium for the first time. It is suggested that the identified components may be at least, a key factors in the observed phytotoxic activity and the data presented may contribute to the development of naturally occurring herbicides. [Copyright &y& Elsevier]

Abstract: The vigorous vegetative reproduction of intolerant deciduous competition limits the efficacy of mechanical release operations in young softwood plantations. Applying bioherbicides such as the fungus Chondrostereum purpureum (Pers. ex Fr.) Pouzar could improve the effectiveness of release by reducing stump sprouting while gaining public acceptance. A field experiment was conducted in Québec (Canada) in two white spruce (Picea glauca [Moench] Voss) plantations invaded by intolerant hardwoods. This study compared four-year response of traditional mechanical release and mechanical release with an application of C. purpureum under the commercial formulation Myco-Tech™. The general objective of the project was to measure the silvicultural efficacy and worker productivity related to applying C. purpureum to control intolerant hardwoods in young white spruce plantations. The potential of C. purpureum was somewhat expressed four years after treatment by reducing paper birch (Betula papyrifera Marsh.) competition. However, because of the slight effect of the treatment on pin cherry (Prunus pensylvanica L.f.), red maple (Acer rubrum L.) and trembling aspen (Populus tremuloïdes Michx.), the addition of the biological treatment did not significantly improve light availability and morphological parameters (height, diameter) of white spruce seedlings. A 2.6-fold reduction in worker productivity compared to traditional mechanical release was caused by the additional operations and weight of the equipment used for the application of the Myco-Tech™ paste. The conditions that facilitate the operational application and effectiveness of C. purpureum applied in the form of the Myco-Tech™ paste do not seem to be present in young conifer plantations with a high density of intolerant hardwood competition. [Copyright &y& Elsevier]

Abstract: Molecular genetic tools and concepts are in relentless and continuous development, affecting every field of biology. Biological control of weeds, an applied science with over a century of history, is no exception. There are many examples of successful biocontrol of weeds, in some cases quite spectacular. However, biocontrol is not applicable to every weed challenge, in large part due to the limitations of available biocontrol agents. Indeed, one cannot realistically expect that naturally occurring agents have serendipitously evolved to meet all of man''s weed control needs. In cases where agents are lacking, molecular biology may be able to improve biocontrol, reduce dependence on chemical herbicides, and control intractable weed species. In theory, any biological weed control strategy could be improved through molecular biology, whether by improvement to a biocontrol agent (e.g. increased lethality, improved specificity, ability to work in concert with other pest management tactics), improvement of the crop (e.g. improved weed-inhibiting properties), by increasing knowledge about the evolution of the target and its natural enemies to assist the search for and selection of classical biocontrol agents, or even by genetic manipulation of the target weed itself. Molecular genetic technology can enable novel strategies that would not be possible in its absence, as well as allow weed researchers to adapt molecular solutions from other fields, including biocontrol of other pests or fields only remotely connected to weed biocontrol. This paper will review concepts of weed biocontrol and molecular biology applications to weed control, as well as propose novel weed-control strategies. [Copyright &y& Elsevier]

Abstract: Valdensinia heterodoxa (Sclerotiniacae) is a potential fungal bioherbicide for control of salal (Gaultheria shallon). The effect of culture media, substrates and relative humidity (RH) on growth, sporulation and conidial discharge of V. heterodoxa was determined for two isolates PFC2761 and PFC3027 in vitro. Culture media significantly affected the growth, sporulation, and conidial discharge of V. heterodoxa. Of eight agar media used, colony radial growth was optimal on salal oatmeal agar and salal potato dextrose agar for isolates PFC2761 and PFC3027, respectively; whereas sporulation was at an optimum on salal oatmeal agar for both isolates. Of the eight liquid media tested, mycelial production was highest on wheat bran–salal–potato dextrose broth. Growth on solid substrates greatly stimulated sporulation and conidial discharge of V. heterodoxa. Of the 12 solid substrates used, the greatest numbers of discharged conidia were observed from wheat bran and wheat bran–salal within 14d of sporulation. Sporulation on solid substrates continued for 42d. RH significantly affected the sporulation and conidial discharge for both isolates across all solid substrates tested. No conidia were produced or discharged below 93 % RH on wheat bran–salal and millet. With an increase of the RH from 93 to 97 %, sporulation and the number of discharged conidia increased significantly for both isolates on wheat bran–salal, but not on millet. [Copyright &y& Elsevier]

Abstract: Recent initiatives by the pesticide regulatory departments of European and North American governments have significantly renewed interest in biopesticide technologies as alternatives for pest management following plans to deregister many chemical pesticides within the next 10 years. The literature is abundant with studies on screening for microorganisms with attributes of biopesticidal activity, however, very few of the authors have considered formulating the microorganisms with commercial applications in mind. A concerted plan in formulation development for biopesticides and bioinoculants by multi-disciplinary teams is required to optimize biopesticide yield, efficacy, storage stability and delivery for this technology to evolve and meet today''s agricultural demands. [Copyright &y& Elsevier]

Abstract: Several plants in the genus Amaranthus are weeds in cropping systems throughout the world, and some biotypes have developed resistance to a number of herbicide families. In an effort to develop alternative, biologically based weed management tactics, studies were initiated to quantify the selective ability of two fungal organisms to several Amaranthus species. Response of weed seedlings to Microsphaeropsis amaranthi (3×106 conidia.ml−1), Phomopsis amaranthicola (1×107 conidia.ml−1), and a mixture of the two organisms (1.5×106+4×106 conidia.ml−1, M. amaranthi and P. amaranthicola, respectively) were tested under controlled and field conditions at Urbana, IL in 2004. Weeds included Amaranthus rudis; A. palmeri; A. powellii; A. retroflexus; A. spinosus; A. hybridus; A. albus; and A. blitoides. Seeds of each species were sown in the greenhouse, and conidial suspensions were applied at the 2- to 4-leaf stage, and then pots were placed either in a dew chamber (24h) and back in the greenhouse, or in the inter-row of a soybean field. Treatment with fungal organisms infected most weeds, reducing growth and survival, although responses in the greenhouse were less than those observed in the field. Percent seedling mortality for A. albus and A. blitoides were between 80 and 100%, 14 to 15 DAT for the mixture or M. amaranthi alone, in greenhouse and field trials. In the greenhouse, the mixture of two organisms and M. amaranthi alone significantly reduced A. albus and A. blitoides height. Fungal treatments reduced biomass of A. powellii, A. albus and A. blitoides. In field experiments, all eight weed species treated with M. amaranthi or the mixture of both organisms had severe disease ratings 15 DAT, and mortality ranged from 74% to 100%. In addition, these treatments reduced biomass of A. rudis, A. retroflexus, A. spinosus, A. hybridus, and A. albus. Height of A. rudis, A. hybridus, and A. albus was reduced by all fungal treatments. This research indicates seedlings of several Amaranthus species are susceptible to conidial suspensions of P. amaranthicola and M. amaranthi in both controlled and field environments. [Copyright &y& Elsevier]

Diagnostic molecular markers, generated from random amplified polymorphic DNA (RAPD) and used in polymerase chain reaction (PCR), were developed to selectively recognize and detect the presence of a single strain of the biocontrol fungus Colletotrichum coccodes (183088) on the target weed species Abutilon theophrasti and from soil samples. Several isolates of C. coccodes, 15 species of Colletotrichum, a variety of heterogeneous organisms and various plant species were first screened by RAPD-PCR, and a strain specific marker was identified for C. coccodes (183088). No significant sequence similarity was found between this marker and any other sequences in the databases. The marker was converted into a sequence-characterised amplified region (SCAR), and specific primer sets (N5F/N5R, N5Fi/N5Ri) were designed for use in PCR detection assays. The primer sets N5F/N5R and N5Fi/N5Ri each amplified a single product of 617 and 380 bp, respectively, with DNA isolated from strain 183088. The specificity of the primers was confirmed by the absence of amplified products with DNA from other C. coccodes isolates, other species representing 15 phylogenetic groups of the genus Colletotrichum and 11 other organisms. The SCAR primers (N5F/N5R) were successfully used to detect strain 183088 from infected velvetleaf plants but not from seeded greenhouse soil substrate or from soil samples originating from deliberate-released field experiments. The sensitivity of the assay was substantially increased 1000-fold when nested primers (N5Fi/N5Ri) were used in a second PCR run. N5Fi/N5Ri selectively detected strain 183088 from seeded greenhouse soils as well as from deliberate-released field soil samples without any cross-amplification with other soil microorganisms. This rapid PCR assay allows an accurate detection of C. coccodes strain 183088 among a background of soil microorganisms and will be useful for monitoring the biocontrol when released into natural field soils. [Copyright &y& Elsevier]

[Display omitted] • Eruca sativa defatted seed meal (DSM) was effective in both experiments on both weeds seeds. • Eruca sativa DSM caused an unexpected auto-toxic phenomenon on Eruca sativa seeds. • Sylibum marianum and Cynara cardunculus showed divergent behaviours to treatments. Exploiting typical allelopathic molecules released from the glucosinolate-myrosinase system could represent a sustainable strategy for weed management in the near future. The present study investigates the potential bioherbicidal efficacy of Eruca sativa cv. Nemat defatted seed meals (EDSM) in two independent experiments: the first one explored air release of volatile compounds (biofumigation), and the second one focused on the effectiveness of soluble compounds (soaking). Each experiment was carried out using two weed species – Silybum marianum (L.) Gaertn. (milk thistle) and Malva sylvestris L. (mallow) – and two crops frequently cultivated in the Mediterranean basin – Cynara cardunculus L. (cardoon) and Eruca sativa cv. Nemat (rocket) – as targets. The results suggested a new high-value application of EDSM with both methods on both weeds. Mallow was mainly injured by soaking, while milk thistle was mainly affected by biofumigation. An auto-toxic effect of EDSM was also noted on rocket seeds. [ABSTRACT FROM AUTHOR]

The intensive use of synthetic herbicides over the past 50 years has led to a number of deleterous impacts on the terrestrial and aquatic environment and is a serious challenge to the ability to sustain agricultural production into the future. In order to remedy this problem, the use of biocontrols is rapidly accelerating and initiating the transition of the agricultural system into an agroecological system. Microalgae (in its wider sense, eukaryote and cyanobacteria) from marine and freshwater habitats are known to produce a diverse range of toxic or otherwise bioactive allelochemical metabolites for growth, communication and defense. Between the search for innovative active molecules and the development of new production processes at the dawn of biotechnology, microalgae have an immense potential in their contribution to biocontrol products. Microalgal organisms can be grown in mass cultures enabelling their manipulation for optimal production of bioactive substances, giving them a significant advantage over terrestrial plants in exploring their effectiveness. In this review we will present the structural diversity of allelochemical compounds and their role for microalgae, the competitive advantages that these compounds provide to microalgae compared to competing species, as well as their potential as biological control agents and bioherbicides. • Focuses on marine allelopathy • Highlights allelochemical compounds in marine allelopathy phenomena • Focuses on the potential of microalgae as biocontrol products • Focuses on the potential of microalgae as a natural bio-herbicide in in vivo and in vitro models • Spotlights the commercial potential of microalgae in the search for alternative bio-herbicidal products [ABSTRACT FROM AUTHOR]

Alternative sources for weed control are necessary to reduce the use of synthetic herbicides. Bioherbicides obtained from agro-industrial waste have the potential to integrate sustainable management of existing agricultural systems. Because of the need for new compounds with potential herbicide, this study's objective was to evaluate the bioherbicidal effect and the enzymatic activity of the extracts produced using agro-industrial waste as a substrate. A submerged fermentation was carried out with orange peel and shrimp shell; Trichoderma koningiopsis and Rhizopus stolonifer were used separately to produce enzymatic extracts. Through submerged fermentation with these agro-industrial residues, extracts were obtained, which were characterized concerning the activities of pectinase, cellulase, amylase, laccase, and peroxidase. The extracts were also evaluated for their bioherbicidal potential for weed control, and this is the first study conducted with these residues for this purpose. No significant difference was observed in the enzymatic activities of the extracts produced by the different microorganisms used. Accentuated leaf damage was observed in C. sativus seven days after applying both extracts, ranging from 66.67 to 77.08% for extracts of T. koningiopsis and R. stolonifer , respectively. Therefore, the extracts appear to be promising alternatives in weed control just seven days after application, demonstrating a rapid effect with low environmental risk. [Display omitted] • Orange peel and shrimp shell as a substrate to produce bioherbicide. • Fungus isolated from strawberry has the potential to produce bioproducts. • Extracts by T. koningiopsis and R. stolonifer stolonifera had a higher phytotoxic effect. • Biocontrol effects were observed after 7 days of treatment with fungal extracts. [ABSTRACT FROM AUTHOR]

• Nano-encapsulation of essential oil increased its herbicidal activity. • 18 formulations of savory essential oil nano-encapsulation were evaluated. • Formulation with slower release rate showed higher phytotoxic ability. • Possible mechanism of action of the applied formulations was investigated. • Nano-encapsulated essential oil has potential for use as natural herbicide. Excessive uses of chemical pesticides have resulted in the occurrence of a wide array of problems consequently using plant natural products is gaining more attention. In this study, different concentrations of savory (Satureja hortensis L.) essential oil (control, 5, 10 and 15 ml/L) were nano-encapsulated using Arabic gum (AG), Persian gum/gelatin (PGG), Persian gum (PG) as wall materials. The nanocapsules had their herbicidal activity against tomato (Lycopersicon esculentum Mill.) and amaranth (Amaranthus retroflexus L.) evaluated by measuring 18 physiological and biochemical parameters. The average size of the nanocapsules varied between 81 and 208 nm, while polydispersity index showed variation between 0.210 and 0.536. The encapsulation efficiency of nanoparticles varied between 72.1–92.8 %. Nano-encapsulated herbicides (NCHs) stability was investigated for 42 days and a mathematical model was followed during oil release. Nano-encapsulated herbicides showed considerable herbicidal activity against amaranth while they had a mild effect on tomato. Moreover, herbicidal activity results exhibited the improvement of encapsulated savory essential oil (EO) efficiencies as compared to non-nano EO emulsion (without polymer). The greatest and fastest injury to amaranth caused by encapsulated EO using cross-linked Persian gum at 15 ml/L which asserted 100 % weed control after 48 h. The aforementioned data suggest the encapsulation of essential oils by biopolymers and with the help of cross-linkers can be used as a valuable tool for the production of organic, natural herbicides. [ABSTRACT FROM AUTHOR]

Abstract Regular application of weedicides has led to multiple toxic effects on human health, environment, and food safety which also facilitated an emergence of weed resistance. Development of bioherbicides using microorganisms has attained considerable attention nowadays for weed management in agricultural fields. In the present study, a rhizospheric bacteria, H6, showing a weedicide efficacy was discovered from the rhizosphere of Momordica charantia. By classical methods and 16S ribosomal DNA phylogenesis, H6 was identified as Pseudomonas aeruginosa. The weedicidal prospective of the secondary metabolites bred by H6 was investigated. Broth, supernatant culture and crude extract of H6 showed high inhibition activity in Pennisetum purpureum , Oryza sativa, Pisum sativa , and Amaranthus spinosum. In general, germination inhibitions of selected weeds were shown by metabolites of the strain H-6. Metabolite identified from strain H6 shows the presence of antifungal and herbicidal compounds. The herbicidal metabolites produced by Pseudomonas aeruginosa H6, was determined by GC- MS analysis. The results revealed that quinoline derivatives which are highly toxic to the target weeds were the distinctive metabolite found within Pseudomonas aeruginosa H6, making it a potential bioherbicide against weed growth. Hence, the results of the present investigation suggest that Pseudomonas aeruginosa H6 can be a suitable alternative to agrochemicals for weed management. [ABSTRACT FROM AUTHOR]