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In recent years, interest in natural products with herbicidal activity as new tools for integrated weed management has increased. The European Union is demanding a reduction in the number of herbicides used, forbidding use of the most toxic ones, despite the problem of weed resistance increasing. Pelargonic acid (PA) is the only natural herbicide available in Spain. In this work, two field assays were performed with the natural compounds carvacrol (CAR), citral (CIT), eugenol (EUG), thymol (THY), p-cymene (P-CYM), (PA), and the combination of PA with CIT—all except P-CYM formulated by Seipasa—to test their herbicidal efficacy in real conditions. They were compared with commercial PA, glyphosate (GLY) and oxyfluorfen (OXY). In both experiments, GLY achieved the best weed control. Considering the natural herbicides, PA formulated by Seipasa and PA plus CIT were the most effective. From both experiments, some conclusions can be extracted for better herbicidal performance of natural products: (1) use products on sensitive weed species, (2) treat weeds at earlier phenological stages, (3) find the active doses in field conditions, (4) cover weeds well when treating, (5) ensure adequate formulation of products, and (6) develop a strategy for correct application. [ABSTRACT FROM AUTHOR]

Leaf spot disease caused by Alternaria perpunctulata (E.G. Simmons) poses a significant threat to Alternanthera philoxeroides (Mart.) Griseb, commonly known as alligator weed and Ceylon Spinach, contributes to persistent weed proliferation in Indian paddy fields. This study focuses on the molecular identification and phylogenetic analysis of the Alternaria perpunctulata strain GVKNSV7, which is responsible for leaf spot disease on A. philoxeroides. Diseased plant leaves were collected from Kakumanu Mandal, Guntur, and local vegetable markets of Visakhapatnam, Andhra Pradesh, India, in December 2021, revealing symptomatic samples with pink to reddish spots on A. philoxeroides leaves. Employing a comprehensive approach that included morphological assessment, pathogenicity testing, and ITS region sequencing, the isolated fungus was conclusively identified as A. perpunctulata with a high sequence similarity of 98.54%. Molecular comparison with sequences in the NCBI database further validated this identification. The resulting genetic sequence, formally catalogued as "Alternaria perpunctulata GVKNSV7," with the GenBank accession number OQ073752, has been successfully submitted to the NCBI database. This study emphasized the utility of ITS sequencing and molecular analyses for accurately identifying and documenting emerging pathogens. Such documentation provides essential insights for developing future bioherbicides and effective weed management strategies. Furthermore, it highlights the potential use of A. philoxeroides as a leafy vegetable, contributing to food security and agricultural sustainability. Overall, this research contributes to understanding Alternaria perpunctulata and its implications for crop health and management practices. [ABSTRACT FROM AUTHOR]

Barley straw has been used around the world for decades as a simple, cost-effective and harmless phytoplankton growth inhibition method. Although the effect of this method on algal blooms is quite well depicted, it has not yet been tested what effect it has on submerged vascular plants and if it could be used to control the spread of alien macrophytes. In this study two highly invasive plant species: Cabomba caroliniana and Elodea nuttallii were exposed to different concentration of the barley straw extract (BSE) in laboratory conditions for a duration of four weeks. In the course of the investigations, responses of 8 traits associated with growth, biomass and chlorophyll concentration of specimens to three dosages (Low, Medium, High) of BSE corresponding to concentrations: 0.03, 0.30 and 1.50 ml l−1 were analysed. The result showed that although dry mass and total length of the plants did not differ significantly between the test groups, increase in tillering and internodes number was observed for certain concentrations of the extract. This shows that if BSE has any effect on submerged macrophytes it is a positive one and thus the method is not suitable for invasive submerged aquatic plant control. Furthermore, it is recommended that before using barley straw for algae bloom control one should make sure that there are no alien aquatic submerged plants in the area that could benefit from such a treatment. [ABSTRACT FROM AUTHOR]

The continued use of synthetic herbicides to control weeds leads to environmental pollution and health issues. Consequently, chemical formulations have been increasingly banned. However, sustainable solutions are lacking in the market. Alternatively, valorisation of phytotoxic waste to reduce the herbicides use promotes sustainability, meeting circular economy. We aimed at assessing the herbicidal potential of aqueous extracts of waste from the management of invasive plants (Acacia dealbata bark, Oxalis pes-caprae biomass) and agri-food (spent coffee grounds) on common urban weeds (Achillea ageratum, Conyza canadensis and Dittrichia viscosa) in Portugal. In vitro (paper and soil) and pot assays (soil) were conducted to test the pre-emergence (germination and seedlings) and post-emergence (well-stablished plants) effect of waste extracts on these weeds. Extracts reduced pre-emergence performance of weeds, but marginally affected post-emergence parameters. Germination was inhibited up to 83% by O. pes-caprae in A. ageratum, up to 88% and 87% by A. dealbata and O. pes-caprae in C. canadensis, and up to 70% by concentration in D. viscosa. A. dealbata and O. pes-caprae extracts also drastically reduced radicle length (30% and 55% in A. ageratum, 77% and 81% in C. canadensis, 90% and 92% in D. viscosa, respectively). However, soil neutralized the inhibitory pre-emergence effect. The main findings highlight that the use of A. dealbata and O. pes-caprae extracts as bioherbicides may require an additional synthetic herbicides application, as extracts alone cannot fully control urban weeds in areas without soil. Combining bioherbicides and commercial formulations still reduces the application of toxic chemicals, promoting sustainability. [ABSTRACT FROM AUTHOR]

This article offers a critical analysis of the evolution of encapsulation methods for herbicides and natural products, with a main focus on organic formulations. It extols the possibilities presented by these micro- and nanomaterials, such as their slow release, stability, bioavailability, water solubility, and stability for classical and natural herbicides from their origins to the present. [ABSTRACT FROM AUTHOR]

Radicinin is a phytotoxic dihydropyranopyran-4,5-dione isolated from the culture filtrates of Cochliobolus australiensis, a phytopathogenic fungus of the invasive weed buffelgrass (Cenchrus ciliaris). Radicinin proved to have interesting potential as a natural herbicide. Being interested in elucidating the mechanism of action and considering radicinin is produced in small quantities by C. australiensis, we opted to use (±)-3-deoxyradicinin, a synthetic analogue of radicinin that is available in larger quantities and shows radicinin-like phytotoxic activities. To obtain information about subcellular targets and mechanism(s) of action of the toxin, the study was carried out by using tomato (Solanum lycopersicum L.), which, apart from its economic relevance, has become a model plant species for physiological and molecular studies. Results of biochemical assays showed that (±)-3-deoxyradicinin administration to leaves induced chlorosis, ion leakage, hydrogen peroxide production, and membrane lipid peroxidation. Remarkably, the compound determined the uncontrolled opening of stomata, which, in turn, resulted in plant wilting. Confocal microscopy analysis of protoplasts treated with (±)-3-deoxyradicinin ascertained that the toxin targeted chloroplasts, eliciting an overproduction of reactive singlet oxygen species. This oxidative stress status was related by qRT-PCR experiments to the activation of transcription of genes of a chloroplast-specific pathway of programmed cell death. [ABSTRACT FROM AUTHOR]

Prosopis juliflora (Sw.) DC. Is highly recognized for its invasive character and its detrimental effects on different plant species across the world. In this study, a field survey was performed to assess the impact of P. juliflora on the surrounding native plants, followed by the effect of different concentrations of its aqueous leaf extract on seed germination and seedling growth of selected Qatari flora. Our field observations indicated a high prevalence of new recruitments of P. juliflora than other native-associated plants in the study site. Germination percentage and/or seed radicle length of the test species: Acacia tortilis (Forssk.) Hayne, Prosopis cineraria (L.) Druce, Sueda aegyptica (Hasselq.) Aellen, Halopeplis perfoliata (Forssk.) Bunge ex Schweinf. & Asch, and P. juliflora were significantly (p ≤ 0.05) reduced by the extracts at different concentration levels. Moreover, the germination rate of A. tortilis was not affected; however, the seed germination of P. cineraria was significantly affected at concentrations of 6 and 8 mg mL−1. The seed radicle lengths at 2 mg mL−1 were significantly reduced for both plant species. The seed germination and radicle length of S. aegyptica and H. perfoliata were significantly decreased at 2 mg mL−1 of extract of P. juliflora. Furthermore, the height and biomass of the seedlings of Aeluropus lagopoides (L.) Trin. ex Thwaites, Caroxylon imbricatum (Forssk.), and Tetraena qatarensis (Hadidi) Beier & Thulin were significantly reduced by the aqueous extracts at 6 and 8 mg mL−1. The aqueous extract reduced the seed germination and seedling growth at 6 and 8 mg mL−1, indicating an autotoxic effect. Such allelopathic behavior of P. juliflora designates the potential investigation of using its allelochemicals as naturally based herbicides in agrosystems. [ABSTRACT FROM AUTHOR]

Essential oils produced by plants, and their components, could be sources of new natural herbicidal compounds. Thirteen oils extracted from six wild Lamiaceae species (namely Clinopodium suaveolens (Sm.) Kuntze, Satureja montana L. subsp. montana, Thymbra capitata (L.) Cav., Salvia fruticosa Mill. subsp. thomasii (Lacaita) Brullo, Guglielmo, Pavone & Terrasi, Satureja cuneifolia Ten., and Thymus spinulosus Ten.) from South Italy were tested in vitro for the phytotoxic activity to cress and branched broomrape seeds, tomato radicles, and lambsquarters leaf disks. Moreover, the possible correlation between oil composition and biological activity was evaluated. One of the oils from T. capitata inhibited cress germination by 96.4% at the lowest tested concentration (100 ppm) and reduced both chlorophyll and carotenoid content in lambsquarters leaf disks by around 50%. Some oils, particularly those from T. spinulosus, inhibited tomato radicle elongation by 85% at 1000 ppm. Many oils inhibited broomrape seed germination up to 100% when tested in solution at 1000 ppm or released as vapors. Among the oil components, α-terpinene, p-cymene, β-cis-ocimene, cis-sabinene hydrate, carvacrol methyl ether, and thymol were mostly correlated to the inhibition of cress seeds germination and tomato radicle elongation. The presence of thymol and p-cymene was also correlated to the inhibition of broomrape seed germination. Some of the tested essential oils or their components could have potential as pre-emergence herbicides and could be useful in the development of new weed control strategies. [ABSTRACT FROM AUTHOR]

Pelargonic acid is a non-selective post-emergence contact bio-herbicide which is registered both for cropping and non-cropping uses in several countries. Dose–response curves on the efficacy of pelargonic acid against common weeds in Mediterranean areas are not available. Dose–response curves of pelargonic acid efficacy against summer and winter annual weeds were evaluated in two field experiments (winter exp. in 2019 and summer exp. in 2020) in central Italy. Pelargonic acid was applied at five doses (1.4, 2.7, 5.4, 10.9 and 21.8 kg a.i. ha−1). Data on weed density, weed dry weight, and weed ground cover were used to calculate the efficacy of pelargonic acid against winter and summer weeds. Data were subjected to a non-linear regression analysis using the logistic dose–response model. Dose of pelargonic acid required to obtain 50%, 70%, 90% and 95% weed control against each weed species (ED50, ED70, ED90 and ED95) were estimated. ED values allowed us to classify winter and summer weeds with respect to their susceptibility to pelargonic acid (ED50 values in kg ha−1 are reported in parenthesis): Kickxia spuria (2.6) (more susceptible) > Heliotropium europaeum (3.0) > Echinochloa crus-galli (3.4) > Solanum nigrum (3.6) > Stachys annua (5.3) > Papaver rhoeas (6.5) > Veronica hederifolia (10.3) > Amaranthus retroflexus (11.4) > Matricaria chamomilla (11.6) > Portulaca oleracea (18.7) > Lolium multiflorum (>21.8) (less susceptible). These findings will allow for the optimization of weed control by pelargonic acid and its use in weed management strategies, both in organic and sustainable cropping systems, under different environmental conditions. [ABSTRACT FROM AUTHOR]

Weed pathogenic fungi play an important role in biological control of weeds. Weeds grow a lot among cultivated plants, the role of weed pathogenic fungi to cultivated plants is not yet known. This research aimed to determine the effect of weed pathogenic fungi on bok choy. The research was carried out in Tambaksogra Village, Sumbang District, Banyumas Regency at an altitude of 100 m above sea level. Randomized block design was used with treatments of weed pathogenic fungi (Fusarium sp., Curvularia sp., Chaetomium sp., Fusarium sp. + Curvularia sp., Fusarium sp. + Chaetomium sp., Curvularia sp. + Chaetomium sp., and Fusarium sp. + Curvularia sp. + Chaetomium sp.) repeated four times. The observed variables included symptoms, incubation period, disease intensity, disease incidence, infection rate, AUDPC, number of leaves, plant height, and plant fresh and dry weight. Results showed that Weed pathogenic fungi of Curvularia sp. and Chaetomium sp. alone or in combination did not affect bok choy indicated by disease intensity of 0 %, and did not affect plant height, number of leaves, and plant fresh weight. The weed pathogenic fungi can be used as a bioherbicide in bok choy. To control weeds in bok choy plantations, both weed pathogenic fungi are recommended to be used. The further application of weed pathogenic fungi needs to be continued to other cultivated plants besides bokchoy. [ABSTRACT FROM AUTHOR]

Meeting the nutritional needs of a dynamically developing global society is a major challenge. Despite the modernisation of agriculture, huge losses in the quality and quantity of crops occur each year, mainly due to weed species, which are the most important biotic limitation to agricultural production. Globally, approximately 1800 weed species cause a 31.5% reduction in plant production, which translates to USD 32 billion per year in economic losses. However, when the same herbicides are frequently applied, plants develop segetal immune mechanisms. There are currently around 380 herbicide-resistant weed biotypes worldwide. Due to the negative influence of herbicides on ecosystems and the legal regulations that limit the use of chemical crop protection products, it is necessary to develop a new method of weed control. Bioherbicides, based on living organisms or their secondary metabolites, seem to be an ideal solution. The biocontrol market is worth around EUR 550 million in Europe and EUR 1.6 billion worldwide, with an estimated 15% growth expected by 2025. Despite numerous studies that have demonstrated the effectiveness of microbial bioherbicides, only 25 mould-based bioherbicides are currently available to growers. Due to the high specificity and selectivity of biological crop protection products, as well as their low production costs and non-toxicity to the environment and human health, they would appear to be a safe alternative to chemical pesticides. [ABSTRACT FROM AUTHOR]

Bioherbicides are naturally originated products posing alternatives to synthetic herbicides for weed control. The objective of this study was to evaluate the efficacy of pelargonic acid and microencapsulated caraway essential oil on barnyardgrass (Echinochloa crus-galli (L.) P.Beauv.) and johnsongrass (Sorghum halepense (L.) Pers.). Two separate pot experiments were conducted at the Agricultural University of Athens (spring 2021), arranged in a completely randomized design (CRD) with six weed control treatments replicated four times. Treatments included the applications of: microencapsulated caraway essential oil at 50 g L−1 (CAR), CAR plus a commercial adjuvant (CAR + adj), i.e., alcohol ethoxylate at 1.8 g L−1, pelargonic acid at 36.3 g L−1 (PA), PA plus a commercial adjuvant (PA + adj), i.e., alcohol ethoxylate at 1.8 g L−1, and a tank mixture of pelargonic acid at 64 g L−1 plus microencapsulated caraway essential oil at 50 g L−1 (PA + CAR). An untreated control (CON) was also included. The results of the current research confirmed the knock-down effect of pelargonic acid against both barnyardgrass and johnsongrass and demonstrated the low efficacy of caraway microcapsules. The addition of a commercial adjuvant improved the efficacy of caraway essential oil but did not appear to affect the performance of pelargonic acid. No synergistic effects were observed between pelargonic acid and microencapsulated caraway essential oil. Further research is needed to optimize the use of these and other natural herbicides for weed control in agriculture and as components of sustainable integrated weed management (IWM) systems. [ABSTRACT FROM AUTHOR]

The utilization of the invasive weed, Parthenium hysterophorus L. for producing value-added products is novel research for sustaining our environment. Therefore, the current study aims to document the phytotoxic compounds contained in the leaf of parthenium and to examine the phytotoxic effects of all those phytochemicals on the seed sprouting and growth of Crabgrass Digitaria sanguinalis (L.) Scop. and Goosegrass Eleusine indica (L.) Gaertn. The phytotoxic substances of the methanol extract of the P. hysterophorus leaf were analyzed by LC-ESI-QTOF-MS=MS. From the LC-MS study, many compounds, such as terpenoids, flavonoids, amino acids, pseudo guaianolides, and carbohydrate and phenolic acids, were identified. Among them, seven potential phytotoxic compounds (i.e., caffeic acid, vanillic acid, ferulic acid, chlorogenic acid, quinic acid, anisic acid, and parthenin) were documented, those are responsible for plant growth inhibition. The concentration needed to reach 50% growth inhibition in respect to germination (ECg50), root length (ECr50), and shoot length (ECs50) was estimated and the severity of phytotoxicity of the biochemicals was determined by the pooled values (rank value) of three inhibition parameters. The highest growth inhibition was demarcated by caffeic acid, which was confirmed and indicated by cluster analysis and principal component analysis (PCA). In the case of D. sanguinalis, the germination was reduced by 60.02%, root length was reduced by 76.49%, and shoot length was reduced by 71.14% when the chemical was applied at 800 μM concentration, but in the case of E. indica, 100% reduction of seed germination, root length, and shoot length reduction occurred at the same concentration. The lowest rank value was observed from caffeic acids in both E. indica (rank value 684.7) and D. sanguinalis (909.5) caused by parthenin. It means that caffeic acid showed the highest phytotoxicity. As a result, there is a significant chance that the parthenium weed will be used to create bioherbicides in the future. [ABSTRACT FROM AUTHOR]

The continued and extensive use of synthetic herbicides to control weeds to maximize crop yield is no longer sustainable, as it results in negative impacts on the environment and human health. Innovative sustainable and resilient food production systems should preserve resources and environmental health by incorporating alternative natural herbicides, recycling waste, and favoring a circular economy. The present work assesses the value of different organic waste (Urtica dioica residues, Vicia faba pods, spent coffee grounds, and corn cobs) as bioherbicides and fertilizers in different seasons through pot and field two-year sequential experiments. Pot assays revealed that V. faba pods, spent coffee grounds, and corn cob waste showed the best inhibitory effect, which were subsequently evaluated in the Spring–Summer and Autumn crops. In the field, spent coffee grounds reduced the biomass of total naturally-emerged weeds and stimulated crop growth under scarce rainfall and warm days. However, its effect varied under different environmental conditions. Spent coffee grounds can partially control weeds in the field, which valorizes them as a bioherbicide and boosts sustainable agriculture. [ABSTRACT FROM AUTHOR]

A large number of studies of Cistus ladanifer highlight this Mediterranean shrub as a source of the phenolic compounds responsible for the allelopathic potential of this species. There are few phenolic compounds present in C. ladanifer that have not yet been studied. The objective of this work was to evaluate the activity of estragole and 2-isopropylphenol on filter paper and soil on monocotyledons (Allium cepa) and dicotyledons (Lactuca sativa). The results showed that when the test was carried out on paper, the germination and the growth of the L. sativa was strongly inhibited by 2 isopropylphenol and estragole. 2 isopropylphenol showed an IC50 on the germination of 0.7 mM and 0.1 mM on the germination rate, 0.4 mM on the size of radicle and 0.3 mM on the size of hypocotyl. Estragole showed an IC50 on the germination rate of 1.5 mM and 1.1 mM on the size of hypocotyl. The effects of these pure compounds on A. cepa were lower, and when the assays were performed on the soil, they were dissipated. The mixture of these compounds on A. cepa had 0.6 mM IC50 for the length hypocotyl on paper and 1.1 mM for the length of the radicle on soil. The mixture on L. sativa also inhibited the length of the radicle with an IC50 of 0.6 mM. On the other hand, it was also observed that estragole stimulated the growth of the A. cepa radicle length on soil, showing a hormetic effect with an EC50 of 0.1 mM. In conclusion, it can be said that for a species to be allelopathic in nature, it is essential to verify the effect of its possible allelochemicals on the target species, on the soil in which they will exert their action and at the concentrations found in their usual environment, in addition to taking into account the interaction with other compounds present in the medium. [ABSTRACT FROM AUTHOR]

Herbicide application has long been considered the most efficient weed control method in agricultural production worldwide. However, long-term use of agrochemicals has numerous negative effects on crops and the environment. Bearing in mind these negative impacts, the EU strategy for withdrawing many herbicides from use, and modern market demands for the production of healthy and safe food, there is a need for developing new effective, sustainable, and ecological weed control measures. To bring a fresh perspective on this topic, this paper aims to describe the most important non-chemical weed control strategies, including ecological integrated weed management (EIWM), limiting weed seed bank, site-specific weed management, mechanical weeding, mulching, crop competitiveness, intercropping, subsidiary crops, green manure, and bioherbicides. [ABSTRACT FROM AUTHOR]

Conyza bonariensis (L.) Cronquist is a widespread noxious weed with high fecundity, associated with no-till systems such as vineyards and other perennial crops in Mediterranean climates. Seeds germinate in staggered flushes, which leads to a great variation in the growth stage between individuals in the same field, and chemical control becomes challenging. Besides, Conyza species have evolved resistance to herbicides worldwide, particularly to glyphosate. Even though tillage is expected to provide weed-free fields, it negatively affects vineyards, causing erosion, loss of soil structure and a reduction in organic matter or vine growth (shallow roots can be affected), among other effects. Fuel consumption of this management is also very high because recurrent interventions of in-row tiller are required. In this context, bioherbicides, defined as environmentally friendly natural substances intended to reduce weed populations, are a potential tool for integrated weed management (IWM). In this work, the herbicidal effect of the following six products is tested on a glyphosate-resistant C. bonariensis population present in commercial vineyards: T1, mixture of acetic acid 20% and the fertilizer N32; T2, mixture of potassium metabisulfite and pelargonic acid 31%; T3, pelargonic acid 68%; T4, humic-fulvic acid 80%; T5, hydroxy phosphate complex; and T6, potassium metabisulfite. The results showed high field efficacy for T1 and T4 (>80% biomass reduction). For the rest of the products, high efficacy was obtained only in dose–response greenhouse experiments. The present work demonstrates the potential of certain bioherbicide compounds to manage herbicide-resistant weed species, such as C. bonariensis. Therefore, bioherbicides could be successfully incorporated into vineyards for IWM. [ABSTRACT FROM AUTHOR]

Weeds cause higher reductions in crop yield than any other pest or disease; yet they remain underestimated in tropical agriculture. Controlling composite culture of weeds in the crop field is difficult. Continuous use of synthetic herbicides may have an adverse impact on human health and the agro-ecosystem. Natural products such as essential oils, plant extracts, allelochemicals, agricultural by-products and some microorganisms are being studied in this area since they are environmentally friendly and have low toxicity. Being ecologically stable, they may provide an alternative to synthetic herbicides. In this article, we document the research done across the world to establish medicinal and aromatic plants as source of bioherbicides for sustainable agricultural production. [ABSTRACT FROM AUTHOR]

Weeds represent one of the most challenging biotic factors for the agricultural sector, responsible for causing significant losses in important agricultural crops. Traditional herbicides have managed to keep weeds at bay, but overuse has resulted in negative environmental and toxicological impacts, including the increase of herbicide-resistant species. Within this context, the use of biologically derived (bio-)herbicides represents a promising solution because they are able to provide the desired phytotoxic effects while causing less toxic environmental damage. In recent years, bioactive secondary metabolites, in particular those bio-synthesized by endophytic fungi, have been shown to be promising sources of novel compounds that can be exploited in agriculture, including their use in weed control. Endophytic fungi have the ability to produce volatile and nonvolatile compounds with broad phytotoxic activity. In addition, as a result of the beneficial relationships they establish with their host plants, they are part of the colonization mechanism and can provide protection for their hosts. As such, endophytic fungi can be exploited as bioherbicides and as research tools. In this review, we cover 100 nonvolatile secondary metabolites with phytotoxic activity and more than 20 volatile organic compounds in a mixture, produced by 28 isolates of endophytic fungi from 21 host plant families, collected in 8 countries. This information can form the basis for the application of endophytic fungal compounds in weed control. Key points: • Endophytic fungi produce a wide variety of secondary metabolites with unique and complex structures. • Fungal endophytes produce volatile and nonvolatile compounds with promising phytotoxic activity. • Endophytic fungi are a promising source of useful bioherbicides. [ABSTRACT FROM AUTHOR]

The sorption of the allelochemical scopoletin (7-hydroxy-6-methoxycoumarin) was studied in eight agricultural soils and different model sorbents. We also determined its degradation in selected soils and related sorption and degradation results to the expression of scopoletin phytotoxicity in soil towards two model plant species, Eruca vesicaria and Hordeum vulgaris. Scopoletin was sorbed to a greater extent in acid soils than in alkaline soils. Correlations with soil properties indicated that the soil pH and fine (silt/clay) fraction played a primary role in the sorption of scopoletin by soils. Weak interactions controlled its sorption in acid soils, whereas stronger interactions, probably with mineral clay constituents, became more relevant in alkaline clay soils. Dissipation of scopoletin in the soils was microbial-mediated and occurred more slowly in acid than alkaline soils. As a result, the phytotoxic activity of scopoletin was expressed in acid but not in alkaline soil. The results point to the influence that soil properties are expected to exert on the expression of the phytotoxicity of scopoletin in natural and agricultural ecosystems. [ABSTRACT FROM AUTHOR]

• The phenological stage has a greater impact on C. ladanifer EOs than plant age. • The C. ladan EOs were rich in terpene-oxygenated compounds. • The EO exhibited a strong dose-dependent phytotoxic effect. • Phytotoxic activity varied according to the ontogenic factors studied. In recent years, research has focused on the development of next-generation herbicides based on allelochemicals, with a particular emphasis on plant essential oils, such as Cistus ladanifer L. (rockrose) essential oil. This study has evaluated how plant ontogenic factors influence the yield, chemical composition, and phytotoxic activity of C. ladanifer essential oil. The essential oils were extracted by hydrodistillation and analysed by gas chromatography coupled with mass spectrometry (GC–MS). The results revealed that the content of essential oil varied significantly, with higher yields observed during the fruit maturation stage compared to the flowering stage. C. ladanifer essential oils were characterized by their richness in terpene-oxygenated compounds. The most significant finding was that C. ladanifer essential oil displayed potent dose-dependent phytotoxic activity on Raphanus sativus (radish) seedlings, indicating their potential use as a natural bioherbicide in agriculture. Notably, essential oil samples from the fruit maturation stage, which contained higher levels of monoterpenes and sesquiterpenes (both hydrocarbons and oxygenated forms), exhibited greater phytotoxic activity on seed germination and early growth compared to the samples from the flowering stage, which were richer in diterpenes and the group labelled ''others''. Multivariate analyses (PCA and Heatmaps combined with cluster analysis) revealed concordance between modifications in secondary metabolism biosynthetic pathways and their enzymes implicated as responses to diverse plant-specific ecological functions. Finally, by exploring sustainable natural products like plant essential oils, this research contributes to the development of next-generation herbicides that promote crop protection while reducing environmental impact. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mismatches between resident microbial communities and introduced weed biocontrol pathogens may lead to agent establishment failure. • Plant pathobiomes play an important role in the survival and success of plant pathogens. • Adapting approaches used in animal and crop pathology will improve our understanding of weed pathobiomes. • Weed biocontrol research should begin to incorporate standardized microbial community data collection during new pathogen releases. The role of microbial communities in the establishment of plant pathogens introduced to new environments as weed biocontrol agents is relatively unexplored. Substantial evidence from crop protection research shows how bulk microbial communities influence the establishment, survival, and success of pathogens. Just as mismatches between biocontrol agents, host genotypes, and climate can lead to establishment failure, we propose that mismatches between microbial biocontrol agents and resident microbiomes may be a cause of apparent weed biocontrol failures. From this perspective, we discuss recent progress in research on plant-associated microbial communities whose interactions influence disease development, or "pathobiomes," and consider the implications for biocontrol agent evaluation and release. Open questions about how weed pathobiomes develop and influence agent success rates provide ample opportunity for researchers to adapt new methods and analytical frameworks that will enhance biocontrol programs. We conclude by prioritizing the development of standard methods to include microbiomes as a component of release studies. Developing a pathobiome-aware agent selection and release process will improve agent establishment rates and biocontrol outcomes. [ABSTRACT FROM AUTHOR]

Plant pathogens have played an important role in weed biological control since the 1970s. So far, 36 fungal pathogens have been authorized for introduction across 18 countries for the classical biological control of weeds. Their safety record has been excellent, but questions continue to be asked about the risk that they could transfer to other plants. Quantitative data documenting their impact on the weed populations are still limited. Of the 15 bioherbicides based on living microorganisms that have ever been registered, only two were commercially available at the time of this review. The development and commercialization of bioherbicides in affluent countries are still plagued by technological hurdles and limited market potential. Not-for-profit small-scale production and distribution systems for bioherbicides in low-income countries may have potential as an inexpensive approach to controlling pervasive weeds. The types of research underpinning biological control approaches and challenges encountered are highlighted using specific examples. [ABSTRACT FROM AUTHOR]

Cassia alata (Caesalpiniaceae), an ornamental shrub, has many biological properties such as antifungal and antibacterial activities. Several bioactive and phytotoxic compounds have already been isolated from C. alata. Phytotoxic substances from plants have drawn attention as an alternative biological approach to control weeds. Thus, we conducted this research to explore other phytotoxic compounds in C. alata leaves. Aqueous methanol extracts of C. alata leaves strongly inhibited the seedling growth of broccoli, cabbage, cress, radish and rapeseed, in which the level of inhibition correlated with concentration. Two active compounds were isolated through chromatographies and identified using spectral data as (S)‐4‐(3‐hydroxybutyl)phenol [(+)‐rhododendrol] and (E)‐4‐((1R,4R)‐4‐hydroxy‐2,6,6‐trimethylcyclohex‐2‐en‐1‐yl)but‐3‐en‐2‐one [3‐hydroxy‐α‐ionone]. These two active compounds inhibited the growth of cress seedlings in a concentration‐dependent manner. The required concentrations for 50% growth inhibition (I50 value) of cress seedlings were 192.0–296.1 μM for (+)‐rhododendrol and 132.4–195.3 μM for 3‐hydroxy‐α‐ionone. These results indicate that the two phytotoxic compounds play a part in the phytotoxic activity of C. alata leaves. [ABSTRACT FROM AUTHOR]

Summary: The use of bioherbicides containing fungal active ingredients or natural fungal molecules is one of the possible solutions to reduce the use of chemical products. This paper focuses on studies of bioherbicides, including both living fungi and natural fungal molecules, published in the last 45 years, and their associated weed targets; current problems in the development of bioherbicides are also discussed. Bibliometric methods based on the Web of Science database were used to analyse relevant articles published between 1973 and 2018. Overall analysis suggested that interest in bioherbicides extends over the preceding thirty years, when many potential microorganisms and natural fungal molecules were proposed. Furthermore, analysis of about 229 articles indicated an encouraging exploitable potential, although there is a real gap between the number of experimental studies and the small number of products currently on the market. A dozen fungal‐based bioherbicides are on the market in the United States and Canada, while countries, such as China and South Africa, have one, and none is available in Europe. The active ingredients in these bioherbicides are living fungi, but no fungal molecule‐based product is thus far on the market. Reasons for this gap include production hurdles, formulation process, ecological fitness, duration of herbicidal effects, and costly and time‐consuming registration procedures. However, it is clear that analysis of fungus–plant interactions provides a promising source of bioherbicides that may be applied to appropriate cropping systems for environment‐friendly, sustainable weed control. [ABSTRACT FROM AUTHOR]

The evaluation of the inhibition effect exerted by the essential oils of basil (Ocimum basilicum), sage (Salvia officinalis), thyme (Thymus vulgaris), lemon balm (Melissa officinalis) and goldenrod (Solidago virgaurea) on seeds germination and early seedling growth of velvetleaf (Abutilon theophrasti Medik.) weed was examined in a laboratory bioassay. The essential oils were obtained by hydrodistillation and characterized chemically by gas chromatography coupled with both mass spectrometry and flame ionization detector. The working solutions of essential oil emulsified with Tween 20 and dissolved in distilled water were prepared at three concentration levels (0.01%, 0.1% and 1%, vol/vol). The results obtained showed that increase of essential oil concentration leads to decrease of seed germination, shoot and radical length of velvetleaf. The obtained data revealed a highly significant effect (P < 0.05) between control and 1% and 0.1% oil concentrations in all treatments. The essential oils of basil, thyme and lemon balm exhibited more powerful bio-herbicidal effect compared to sage and goldenrod essential oils on the germination and early seedling growth of velvetleaf weed. [ABSTRACT FROM AUTHOR]

The exacerbated application of chemical control in agriculture brings several damages to the environment and man, as the herbicides are one of these routinely used tools. In this sense, the following study was carried out with the objective of evaluating by means of factorial planning 23 which factors should be considered to obtain better experimental results of the germinative inhibitory activity. Therefore the allelopathic action of the aqueous extracts of Stryphnodendron adstringens and Anemopaegma arvense, obtained at two temperatures (250C and 1000C) and two types of receptors (Lactuca sativa seeds and Lycopersicum esculentum seeds). The tests were performed in duplicate with the 50% and 100% (v/v) concentrations of each extract. Therefore, the temperature of the extracting solvent, characteristic of the receiver seed and concentration of the aqueous extract of the medicinal plant, are the factors observed in this experimental design The results of the factorial planning showed that the seed factor was predominantly influencing the activity of S. astringens and A. arvense as inhibitors of germination of L. sativa and L. esculentum, respectively, therefore reinforcing that the plant-plant interaction follows an ecophysiological specificity. [ABSTRACT FROM AUTHOR]

Although seed meal from yellow mustard ( Sinapis alba L.) is a potential tool for controlling weeds as a consequence of produced phytotoxic products, use is limited by batch-to-batch variability and logistical constraints. Our objective was to develop an efficacious bioherbicide by extracting and identifying the active ingredients in S. alba seed meal that demonstrate phytotoxicity to greenhouse-grown Powell amaranth ( Amaranthus powellii ) and green foxtail ( Setaria viridis ). Companion bioassays with separate potential active ingredient solutions containing ionic thiocyanate (SCN − ), 4-(hydroxymethyl)phenol (4-OH), or 2-(4-hydroxyphenyl)acetonitrile (Nitrile) at concentrations approximating those in the extract were performed. When applied pre- (PRE) or postemergence (POST), SCN − and extracts were the most active solutions on both weed species. The highest rate tested of SCN − of 2.8 kg ha −1 controlled Powell amaranth 98% and green foxtail 84% compared to the highest rate of extract (2.8 kg SCN − ha −1 ) that controlled Powell amaranth 97% and green foxtail 82%. POST application of the extract was less effective as compared to SCN − solutions, with SCN − showing 97% control of Powell amaranth and 71% control of green foxtail as compared to the extract displaying only 46% control of Powell amaranth and 23% control of green foxtail. Little or no herbicidal activity was observed on both weed species following PRE or POST application of 4-OH or Nitrile. Development of a bioherbicide based on extracting and concentrating SCN − from S. alba seed meal is feasible, especially if scale up activities focus on eliminating the need for alcoholic extractants and yield higher active ingredient products. [ABSTRACT FROM AUTHOR]

Weeds constitute major losses to crops which necessitates the use of control practices. In conventional management systems, weeds are typically controlled using manual, mechanical, and chemical methods. Manual weeding is considered as most efficient control but its use has reduced due to shortage of labor for crop production on large scale and growing cost of labor. Mechanical weeding is suitable only for a limited number of crops and sowing methods. Additionally, requirements for multiple operations and adverse environmental impacts have limited use of mechanical weeding. Reliance on herbicides has increased over time due to convenience in application and quick response. Continuous use of herbicides has disturbed weed ecology, biodiversity, environment, and human health. They have caused herbicide resistance in weeds, shift in weed flora, and yield reduction of sensitive crops. Herbicide drift, persistence in soil, contamination of waterbodies, and accumulation of residues in plants have exposed all life forms to their hazardous effects. They are held responsible for many health disorders in human beings. So many challenges have been posed by chemical herbicides that the cost of weed control and limitations of other control methods now necessitate development of alternative techniques for at least integration into existing weed management practices. These alternative techniques may be based on biological approaches, i.e., inoculative biological control, inundative biological control, and allelopathy. A detailed review of limitations of currently used control methods and the feasibility of development of alternative techniques especially opportunities offered by rhizobacteria for weed management are discussed in this chapter. [ABSTRACT FROM AUTHOR]

Formulation of effective and environmental friendly bioherbicides depends on the type of fermentation medium used for the production of phytotoxic metabolites. The effect of biomass, colony forming unit and the phytotoxic metabolite produced from the biphasic fermentation was carried out, while the phytotoxic metabolite was tested in vivo and in-vitro on Echinochola crus-galli and dicotyledonous Chromolaena odorata. The mutant strain of Lasiodiplodia pseudotheobromae C1136 (Lp90) produced the highest amount of conidia and the largest necrotic area on the two tested weeds when compared to its wild strain in the different biphasic media combinations. The study revealed that the biphasic system containing PDB + rice produced the highest bioherbicidal activities. Therefore, the phytotoxic metabolites from strain C1136 are suggested for large scale production of bioherbicides for the management of weeds in conventional farming to improve yield and enhance food security. [ABSTRACT FROM AUTHOR]

The use of phytopathogenic fungi in biological control of weeds may represent a promising alternative to the use of chemicals and may lead to the sustainability of agro-ecosystems. In the current study, strain C1136 was developed into various formulations and their activities were compared with a chemical herbicides using glyphosate in a screen house, applying standard procedure. All the bioherbicide treatments gave significantly higher yield component on the following parameters: tasselling, number of cobs, day of silking, number of ears, number of grain/cob, weight of 100 grains, number of cob, weight of cob, and length of cob from maize when compared to the chemical-treated herbicides and weedy cheek. Moreover, the bioherbicidal formulation coded BH4 (32 g of semolina + 6 g kaolin + 20 mL of glycerol + mutant strain of Lasiodiplodia pseudotheobromae + glucose+ sucrose + fructose + dextrose + lactose sugar + peptone) showed the highest activities when compared to other formulations. Conclusively, this study revealed that Lasiodiplodia pseudotheobromae C1136 strain has bioherbicidal activity and could therefore be exploited for large scale production of bioherbicides for weed control in conventional farming, to improve yield and enhance food security. [ABSTRACT FROM AUTHOR]

The herbicidal potential of aqueous extracts prepared from leaves and seeds ofCanavalia ensiformiswas tested by applying them postemergence to the crop weedsIpomoea grandifoliaandCommelina benghalensis. Considering the possible objective of using this bioherbicide on soybean fields, the extracts were also tested for deleterious effects on both transgenic and conventional soybean (Glycine max). In addition, the concentrations of four phenolic compounds and alkaloids with allelopathic properties in these extracts were estimated by high-performance liquid chromatography. The seed extract at concentrations of 25 g L−1and 50 g L−1was the most efficient postemergent bioherbicide. By applying these extracts, the development of the weed seed was progressively hindered until no recovery was observed. The application of 3.5 mL of crude extract on a plant that takes 30 days after germination of the seed to develop is sufficient for full control of the species within 5 days. Since bothIpomoea grandifoliaandCommelina benghalensisare broadleaf dicotyledons, it is possible that other species with these characteristics can also be controlled or suffer the same effects under the action of the seed extract, if the same volume and mode of application are used. The selectivity of the treatments with 25 g L−1and 50 g L−1was assessed on transgenic and conventional cultivars. The treatments did not visibly affect the soybean cultivars, which developed normally during the observation period that continued up to 15 days after the death of the weeds. [ABSTRACT FROM AUTHOR]

A recent greenhouse study revealed a significant reduction of germination and growth of redroot pigweed ( Amaranthus retroflexus) and common purslane ( Portulaca oleracea) by rye mulch, whereas velvetleaf ( Abutilon theophrasti) and common lambsquarters ( Chenopodium album) were not suppressed. Since BOA detoxification by metabolic alteration may influence the relation between the benzoxazinoid content of the soil mulch and weed suppression, we tested the dynamics in BOA detoxification in different plant organs of three and 10-day-old seedlings of four warm season weeds incubated with five BOA concentrations (4, 20, 40, 80, and 200 μmol g fresh weight). In addition, germination and length of 3-day-old seedlings were measured after exposure to 0, 0.3, 1.5, 3, 6, and 15 μmol BOA. Finally, we tested the influence of the MDR translocator inhibitors verapamil, nifedipine, and the GST inhibitor ethycrynic acid on BOA accumulation and detoxification activity. Due to BOA-detoxification, all weeds were able to grow in environments with low BOA contents. At higher contents, Abutilon theophrasti and Chenopodium album had a better chance to survive because of highly active mechanisms that avoided the uptake of BOA ( A. theophrasti) and of efficient detoxification activities in youngest seedlings ( C. album). The interpretation of all of the data gave the following sequence of increasing sensitivity: A. theophrasti <<< C. album << P. oleracea ≤ A. retroflexus. The results were in agreement with recent findings of the suppression of these weeds by rye mulches and their benzoxazinoid contents. Our studies demonstrate for the first time that the detoxification of BOA influences the survival of certain weeds in environments enriched with this allelochemical. Therefore, detoxification processes affect the potential for weed suppression by soil allelochemicals in sustainable weed management. [ABSTRACT FROM AUTHOR]

Bioherbicides are phytopathogenic microorganisms or microbial phytotoxins useful for biological weed control. Therefore, bioherbicides has been recognized as a significant biological control strategy. They offer many advantages-high degree of specificity of target weed; no effect on non-target and beneficial plants or man; absence of residue build-up in the environment; effectiveness for managing herbicide-resistant (HR) weed populations. Furthermore, it has been demonstrated that combinations of some bioherbicides and synthetic herbicides can be synergistic. Besides many advantages of bioherbicides, certain factors have been reported to limit the development of bioherbicides into commercial products. These include environmental, biological and technical-commercial limitations. [ABSTRACT FROM AUTHOR]

Abstract: Measurements of chlorophyll a fluorescence, nutrient and trace elements, total protein content and malonyldialdehyde in leaves of Arabidopsis thaliana between 1 and 192h after treatment with 0, 1 or 3mM 2-3H-benzoxazolinone (BOA), together with imaging of chlorophyll a fluorescence and of the distributions of hydrogen peroxide and superoxide anion, suggested that the primary phytotoxic action of BOA is the induction of premature senescence, and that oxidative stress is a secondary effect that sets in a day or two later. [Copyright &y& Elsevier]

Abstract: Phoma exigua var. exigua, a fungal pathogen isolated from Cirsium arvense and Sonchus arvensis, proposed as a biocontrol agent of this noxious perennial weeds, produces in liquid and solid cultures different phytotoxic metabolites with potential herbicidal activity. The phytotoxic cytochalasins B, F, Z2, and Z3 and deoxaphomin were previously identified together with p-hydroxybenzaldehyde. Using spectroscopic methods, four new cytochalasins, termed phomachalasins A–D, were isolated and characterized as three new closely related 26-oxa[16] and one new [15]cytochalasans. They belong to a new subgroup of cytochalasans bearing a 1,2,3,4,6,7-hexasubstituted bicycle[3.2.0]heptene joined to the macrocyclic ring. None of the four new metabolites showed phytotoxic or antimicrobial activity. The lack of both phytotoxic and antimicrobial activities showed by all phomachalasins A–D was probably due to the strong modification of both functionalities and conformational freedom of the macrocyclic ring caused by its junction with the bulky and quite rigid new bicycle, namely bicycle[3.2.0]heptene. [Copyright &y& Elsevier]

Green foxtail (Setaria viridis), one of the most common and troublesome weeds worldwide, is becoming very difficult to manage because of the lack of registered herbicides and the appearance of herbicide-resistant populations. Among the new and possible environment-friendly strategies, the use of biological control methods seems to have potential. Drechslera gigantea, Exserohilum rostratum and Exserohilum longirostratum have previously proved to be promising bioherbicide agents against several grass weeds in field trials. While previous studies have established the susceptibility of S. viridis under greenhouse conditions, so far no attempt has been made to establish the effectiveness and feasibility of these fungi as bioherbicides for green foxtail. When spore suspensions were applied as foliar sprays to green foxtail seedlings in a greenhouse, all three fungi caused severe damage by 1 day after application, and seedlings in most cases died within 1 week. The fungi were compatible with several agro-chemicals and host specific when tested against major vegetable crop species grown in the Mediterranean. The demonstrated technological feasibility of producing large amounts of quickly germinable conidia (i.e., asexual spores) on inexpensive solid media increases the potential of these fungi to be used as bioherbicides. [ABSTRACT FROM AUTHOR]

New plant-based products can be produced from seed harvested from Brassica species used for phytomanaging selenium (Se) in the west side of central California. Se-enriched seed meals produced from canola (Brassica napus) and mustard (Sinapis alba) plants were tested as potential bioherbicides and green fertilizers in strawberry production under controlled and field conditions for two seasons. Treatments consisted of adding each meal (containing 2.2 mg Se/kg dry mass) to the soil at rates equivalent to 0, 2, and 6 t/acre, respectively, 7 days before planting, in growth chamber studies, the highest rates of either meal lowered berry yields by a high of 30% compared with no application (control). Among the nutrient accumulation, berry Se, calcium (Ca), manganese (Mn), and zinc consistently increased with most Brassica meal treatments and most significantly with the mustard meal. In the field studies, mustard treatments lowered the emergence of summer-germinating and resident winter annual weeds more than canola and control treatments. Strawberry fruit yields increased with all Brassica treatments, except a 42% fruit yield reduction was observed at a 6 t/acre rate of mustard meal. Increases in fruit Se concentrations and increases in Ca, phosphorus, and Mn were often observed for all Brassica treatments. Amending soils with Brassica seed meals may have more practical viability in organic agriculture as a potential bioherbicide and green fertilizer. [ABSTRACT FROM AUTHOR]

Abstract: Purple nutsedge and yellow nutsedge are serious weeds in Florida and in many parts of the world. Dactylaria higginsii is a promising bioherbicide candidate for these weeds. This fungus does not sporulate in liquid culture. Thus, for mass production of D. higginsii, 19 solid substrates were tested, including dried, cut culms or foliage of 14 different plants prepared as hays, sugarcane bagasse, a commercial peat-based microbe carrier (BioAPT), and two recycled papers (kraft paper and newspaper). These substrates were tested alone or amended either with 0.01% indole butyric acid (IBA), which enhances growth and/or sporulation of D. higginsii, potato dextrose broth (PDB) for nutrient amendment, or PDB+IBA. Yield of D. higginsii conidia produced on these substrates was measured 4 and 12weeks after inoculation. Conidia were tested for virulence on purple and yellow nutsedges in the greenhouse. Hays without amendments or amended with PDB yielded more conidia which were also more virulent than those produced on hays amended with IBA. Conidial yields were highest when the fungus was grown on purple nutsedge hay without amendments for 4weeks but conidia produced on this medium had low virulence. Conidia produced on sorghum×sudangrass and cogongrass hays were slightly larger and thicker walled than those produced on other substrates. Conidia produced on sorghum×sudangrass were the most virulent on nutsedge seedlings. Purple nutsedge was more susceptible to D. higginsii than yellow nutsedge. Cogongrass and sorghum×sudangrass hay substrates offer a suitable and easy medium for large-scale production of D. higginsii. [ABSTRACT FROM AUTHOR]

For many years, researchers have been sceptical as to whether microbial biological control agents, and in particular biopesticides, would be developed for use in areas other than greenhouses and forestry. This perception is slowly changing as the increased development and use of biopesticides in Canada is moving from being a novelty to a reality. This paper examines the role of biopesticides in Canada and the nine stages required to take a microbial biopesticide from discovery through product development, striving for commercialization and adoption by the end user. It highlights examples of Canadian biopesticide innovations that have moved through the innovation chain, illustrating the challenges and rewards along the way. [ABSTRACT FROM AUTHOR]

Abstract: Globally, the use of biopesticides is growing annually while the use of traditional pesticides is on the decline. North America uses the largest percentage of the biopesticide market share at 44%, followed by the EU and Oceania with 20% each, South and Latin American countries with 10%, about 6% in Asia and India. Although biopesticide growth is projected at 10% annually, it is highly variable among the regions constrained by factors such as regulatory hurdles, public and political attitudes, and limitations for market expansion. Microbial biopesticides have been registered in Canada for 35years, but the number of registrations for commercial, restricted-industry and domestic uses has significantly increased over the past 10years. The early Canadian biopesticides registered by pest control category were Bacillus thuringiensis in 1972 as the first bioinsecticide, Agrobacterium radiobacter in 1989 as the first biobacteriocide, Colletotrichum gloeosporioides f.sp. malvae in 1992 as the first bioherbicide, and Streptomyces griseoviridis in 1999 as the first biofungicide. Between 1972 and 2008, the Pest Management Regulatory Agency approved registration of 24 microbially active substances with 83 formulations. The majority of the registrations (55/83) occurred since 2000 and at the beginning of 2008 there were 10 new products (a combination of new active substances, strains, formulations, and uses) under regulatory evaluation. This paper examines the evolution of microbial biopesticides in Canada illustrating how the actions of the government, the people, and the industry have led to changes in legislation, policy, and programming that spurred momentum for new microbial pest control products in recent years and created a model system for future microbial biopesticide discovery, development, and implementation that could be adopted throughout the world. [Copyright &y& Elsevier]

We assessed the effect of three organic amendments and two organo-clays on sorption, persistence, and phytotoxicity of scopoletin, an allelochemical compound with potential as bioherbicide, in a Mediterranean alkaline soil. The aim was to elucidate whether the phytotoxicity of scopoletin could be expressed better in amended than unamended soil. The three organic amendments were fresh solid olive-mill waste (OMW), composted solid olive-mill waste (OMWc), and biochar (BC) prepared from OMWc. The two organo-clays were a commercial organo-montmorillonite (Cloi10) and lab-synthesized oleate-modified hydrotalcite (HT-OLE). The amendments enhanced sorption of scopoletin by the soil consistently with their individual affinities for the allelochemical: Cloi10 ≫ OMW > BC > OMWc > HT-OLE. The soil persistence of scopoletin increased significantly because of the addition of Cloi10, OMW, and BC. This increase was attributed to a combination of sorption, which protected the allelochemical from rapid biodegradation, and microbial activity changes. Although the inhibitory effect produced by the amendments themselves obscured the phytotoxicity of scopoletin to Lactuca sativa L. in soil treated with OMW and Cloi10, applying scopoletin to BC-amended soil led to a marked reduction in root length and aerial biomass of the emerged seedlings even though BC alone did not negatively affect these parameters. This inhibitory effect of scopoletin in BC-amended soil was in contrast to the negligible effect exerted by the allelochemical when applied to unamended soil. The results show that soils treated with suitable amendments, such as BC, might provide a scenario in which the herbicidal properties of 7-hydroxycoumarins could be better expressed. [Display omitted] • Sorption, persistence, and phytotoxicity of scopoletin in amended soil is reported. • Amendments included organic solids (OMW, OMWc, BC) and organo-clays (Cloi10, HT-OLE). • Certain amendments (Cloi10, OMW, BC) enhanced sorption and persistence of scopoletin. • Applying scopoletin to BC-amended soil greatly increased its phytotoxicity. • Amending soils may help potentiate the performance of hydroxycoumarins as bioherbicides. [ABSTRACT FROM AUTHOR]

We assessed the effect of three organic amendments and two organo-clays on sorption, persistence, and phytotoxicity of scopoletin, an allelochemical compound with potential as bioherbicide, in a Mediterranean alkaline soil. The aim was to elucidate whether the phytotoxicity of scopoletin could be expressed better in amended than unamended soil. The three organic amendments were fresh solid olive-mill waste (OMW), composted solid olive-mill waste (OMWc), and biochar (BC) prepared from OMWc. The two organo-clays were a commercial organo-montmorillonite (Cloi10) and lab-synthesized oleate-modified hydrotalcite (HT-OLE). The amendments enhanced sorption of scopoletin by the soil consistently with their individual affinities for the allelochemical: Cloi10 ≫ OMW > BC > OMWc > HT-OLE. The soil persistence of scopoletin increased significantly because of the addition of Cloi10, OMW, and BC. This increase was attributed to a combination of sorption, which protected the allelochemical from rapid biodegradation, and microbial activity changes. Although the inhibitory effect produced by the amendments themselves obscured the phytotoxicity of scopoletin to Lactuca sativa L. in soil treated with OMW and Cloi10, applying scopoletin to BC-amended soil led to a marked reduction in root length and aerial biomass of the emerged seedlings even though BC alone did not negatively affect these parameters. This inhibitory effect of scopoletin in BC-amended soil was in contrast to the negligible effect exerted by the allelochemical when applied to unamended soil. The results show that soils treated with suitable amendments, such as BC, might provide a scenario in which the herbicidal properties of 7-hydroxycoumarins could be better expressed. [Display omitted] • Sorption, persistence, and phytotoxicity of scopoletin in amended soil is reported. • Amendments included organic solids (OMW, OMWc, BC) and organo-clays (Cloi10, HT-OLE). • Certain amendments (Cloi10, OMW, BC) enhanced sorption and persistence of scopoletin. • Applying scopoletin to BC-amended soil greatly increased its phytotoxicity. • Amending soils may help potentiate the performance of hydroxycoumarins as bioherbicides. [ABSTRACT FROM AUTHOR]

To help protect the environment as well as increase agricultural production, the use of synthetic herbicides must be reduced and replaced with plant-based bioherbicides. Elaeocarpus floribundus is a perennial, evergreen, and medium-sized plant grown in different areas of the world. The pharmaceutical properties and various uses of Elaeocarpus floribundus have been reported, but its allelopathic potential has not yet been explored. Thus, we carried out the present study to identify allelopathic compounds from Elaeocarpus floribundus. Aqueous MeOH extracts of Elaeocarpus floribundus significantly suppressed the growth of the tested species (cress and barnyard grass) in a dose- and species-dependent way. The three most active allelopathic substances were isolated via chromatographic steps and characterized as (3R)-3-hydroxy-β-ionone, cis-3-hydroxy-α-ionone, and loliolide. All three substances significantly limited the seedling growth of cress, and the compound (3R)-3-hydroxy-β-ionone had stronger allelopathic effects than cis-3-hydroxy-α-ionone and loliolide. The concentrations of the compounds required for 50% growth inhibition (I50 value) of the cress seedlings were in the range of 0.0001–0.0005 M. The findings of this study indicate that all three phytotoxic substances contribute to the phytotoxicity of Elaeocarpus floribundus. [ABSTRACT FROM AUTHOR]

Abstract: Phyllosticta cirsii, a fungal pathogen isolated from Cirsium arvense and proposed as biocontrol agent of this noxious perennial weed, produces in liquid cultures different phytotoxic metabolites with potential herbicidal activity. Four new oxazatricycloalkenones, named phyllostictines A–D, were isolated and characterized using essentially spectroscopic and chemical methods. Tested by leaf-puncture assay on the fungal host plant phyllostictine A proved to be highly toxic. The phytotoxicity decreases when both the dimension and the conformational freedom of the macrocyclic ring change, as in phyllostictines B and D, and it is totally lost when also the functionalization of the same ring is modified, as in phyllostictine C. Beside its phytotoxic properties, phyllostictine A has no antifungal activity, an interesting antibiotic activity only against Gram+ bacteria, and a noticeable zootoxic activity when tested at high concentrations. The integrity of the oxazatricycloalkenone system appears to be an important feature to preserve these activities. [Copyright &y& Elsevier]

Abstract: The topic of ecological, practical, and political considerations in the selection of weed targets for biological control has been widely discussed during the past two decades, mostly from the perspective of insect herbivores. For conceptual and practical purposes, plant pathogens have been treated in these discussions as if they are a subset of inoculative biocontrol agents, with little said about the inherent differences between pathogens and insects as biocontrol agents or the selection of weed targets for control by the inundative, bioherbicide strategy. Herein, I attempt to address the question of what makes a good biological control target for plant pathogens used as inoculative as well as inundative agents, basing my analysis on examples from the past three decades. Despite the small number of examples available for this analysis, the following generalizations can be made: (1) Weeds with robust capacity for vegetative regeneration are more difficult to control with pathogens than those that lack this trait. (2) A plant’s growth habit is not a reliable guide for target selection; weeds that have been successfully controlled include annual and biennial herbs, perennial shrubs, perennial vines, and trees, while numerous failures have been reported irrespective of the target’s growth habit or reproductive mode. (3) It is more challenging to control species with genetic heterogeneity and capacity for introgression than genetically homogeneous and reproductively conserved species. (4) Matching the target host’s susceptibility with the candidate pathogen’s virulence is of utmost importance for biocontrol success since host–pathogen interactions at the species and subspecies levels are often governed by single-gene differences (e.g., varietal specificity). (5) Practical and political considerations are central to the selection of targets for control with pathogens. (6) Demand from influential stakeholders for control and/or for a nonchemical or economically sustainable control typically drives the initiative as well as the continuance of biocontrol projects to their completion. (7) In the case of inundative, bioherbicide agents, the continuity and ultimate implementation of a project will be dictated by the prospects of economic returns from developing and using a pathogen. (8) The stakeholders’ perceptions of the effectiveness of a biocontrol program can be unpredictable, leading to conflicting views of “success.” In the final analysis, a good weed target for control by a pathogen is one that has strong stakeholder backing and the list of available pathogens for the target suggests a possibility of acceptable control at a cost that is competitive with those of other control options. While this conclusion is also applicable to target selection for insect biocontrol agents, it is more relevant for pathogens because of limited funding and personnel available for development of pathogens and the added cost and technological complexity of implementing bioherbicides compared to classical biocontrols. [Copyright &y& Elsevier]

a-Amino-oxyacetic acid (AOA), 2-deoxy-d-glucose (DDG), mannose, and oxalic acid were tested as possible synergizers to enhance the efficacy of Colletotrichum coccodes , as a biological control agent of Abutilon theophrasti . All the chemicals reduced C. coccodes conidia germination and appressoria formation, but the virulence of C. coccodes was significantly enhanced when C. coccodes was applied to A. theophrasti after mannose and oxalic acid were vacuum-infiltrated through the leaf cuticle. Lipophilic analogues, 1-amino-ethyl-phosphonic acid diisopropyl ester of oxalic acid, oxalic acid diammonium salt, and 4,6-di- O -methyl-d-mannose, did not result in more severe disease on velvetleaf and there was no impact on A. theophrasti growth. These results may be due to strong antifungal effects, possible functional changes due to chemical structural changes, size of the chemical molecule, or lack of inhibitory effect of these chemicals on plant defense mechanisms. It is also possible that the defense mechanisms that these chemicals can influence are not active in A. theophrasti . Comprehensive understanding of the defense mechanisms of A. theophrasti that limit C. coccodes infection and ways to breach these defense strategies should result in improved weed suppression. [ABSTRACT FROM AUTHOR]

Seed infection by the seed-borne pathogen Pyrenophora semeniperda was demonstrated following inundative applications of the fungus to several annual grass weeds and wheat. The optimum time for applying inoculum was found to be around mid-anthesis in wheat. Applications of inoculum during and after anthesis in field experiments resulted in seed infection that manifested as stromatal development which affected germination or reduced seedling vigour. In an initial field experiment, >70% of Bromus diandrus seeds exhibited stromata of P. semeniperda . In a field comparison of inoculum types, conidial suspensions resulted in the greatest level of seed infection of B. diandrus compared with several types of inoculum containing mycelium fragments. Inundation of Avena fatua , Lolium rigidum , Hordeum leporinum , Vulpia bromoides and B. diandrus under field conditions with conidia of P. semeniperda also resulted in either the failure of infected seeds to germinate or a reduction of seedling vigour. It is concluded that the use of P. semeniperda as a seed-borne bioherbicide may be a biologically reasonable tactic, and the many logistical and technological constraints impeding its development are discussed. [ABSTRACT FROM AUTHOR]

Formulation of a bioherbicide ideally should result in a product that has low cost, long shelf-life, ease of application and efficacy. Formulation persists as a constraint to commercial development of many potential bioherbicides often because dew dependence in fungi limits their efficacy under dry-land conditions. This has not been a problem with several commercial bioherbicides because they are used in irrigated systems or applied as wound inoculations. Thus, reduction in dew dependence is a principal aim in the formulation of many potential bioherbicides. In the present paper, formulation research attempting in part to overcome this problem via the development of novel solid and liquid formulations is described. Solid formulations typically must be able to survive in the field and await suitable conditions before becoming activated. Liquid formulations have the potential to produce infections soon after application provided they remain moist on the target plant surface. Several attempts to improve water-holding capacity in liquid formulations have been examined. The use of multiple emulsions of water in oil in water has recently shown promise. [ABSTRACT FROM AUTHOR]

[Display omitted] • Environmental conditions are the dominant factors controlling the spatial distribution of vegetation at large scale • Species co-occurrence can be used to predict allelopathic interaction in Saharan ecosystem with an appropriate scale • The extracts of three Saharan species had significant effects on seeds germination or seedlings growth of target species • Aqueous extracts of the selected species might be alternative bioherbicides in agricultural and environmental management Allelochemicals involved in plant-plant interaction (Allelopathy) are a potential source for alternative agrochemicals to solve the negative effects caused by synthetic herbicides. The present study is focused on the prediction and evaluation of allelopathic plants species in Saharan ecosystem from the Souf region in the southeastern of Algeria. The study was articulated through three steps of investigation: (1) a floristic survey, including a general inventory with notation of abundance and sociability scores for each species to understand the floristic composition of the study area, (2) Species co-occurrence analysis, using a presence/absence of data species in restricted sampling plots, which allowed to identify eight negatively associated species pairs with only one positive association and (3) allelopathic bioassays were performed with the aqueous extracts of the three species negatively associated species. The results showed a significant effect of aqueous extracts of Halocnemum strobilaceum (Pall.) M. Bieb, Retama raetam Forssk. Webb and Limoniastrum guyonianum Boiss on seed germination or seedling growth of target species (Lactuca sativa L. , Daucus carota L., Triticum durum Desf. and Zea mays L.) at concentrations of 10 % and 15 %. H.strobilaceum showed the highest phytotoxic activity with 0% germination rate of all target species at concentration of 15 %, followed by R. raetam and L. guyonianum , and D. carota was the most sensitive target species with total inhibition of germination in most of treatments. Besides, plumule length was most affected then radicle length. It was conducted that some of these extracts may be represent a promising alternative bioherbicides from Saharan plants in agricultural and environmental management. [ABSTRACT FROM AUTHOR]