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Several Acacia species are aggressive invaders outside their native range, often occupying extensive areas. Traditional management approaches have proven to be ineffective and economically unfeasible, especially when dealing with large infestations. Here, we explain a different approach to complement traditional management by using the waste from Acacia management activities. This approach can provide stakeholders with tools to potentially reduce management costs and encourage proactive management actions. It also prioritizes potential applications of Acacia waste biomass for agriculture and forestry as a way of sequestering the carbon released during control actions. We advocate the use of compost/vermicompost, green manure and charcoal produced from Acacia waste, as several studies have shown their effectiveness in improving soil fertility and supporting crop growth. The use of waste and derivatives as bioherbicides or biostimulants is pending validation under field conditions. Although invasive Acacia spp. are banned from commercialization and cultivation, the use of their waste remains permissible. In this respect, we recommend the collection of Acacia waste during the vegetative stage and its subsequent use after being dried or when dead, to prevent further propagation. Moreover, it is crucial to establish a legal framework to mitigate potential risks associated with the handling and disposal of Acacia waste. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor (L.) Moench) is one of the globally important cereal crops well adapted to Sub-Saharan Africa (SSA) agro-ecology. However, the productivity of sorghum is hindered by both abiotic and biotic factors including drought, Striga, insect pests, poor soil fertility, and diseases. Among the constraints, Striga (genus), also called witch weed, is the most important production problem in the area. Although there have been various control methods practiced for years, none of these have been practically effective in eradicating Striga, neither are they easily accessible for small holder farmers, while some are also not environmentally friendly. Therefore, this study was designed with the objective of identifying potential Striga suppressing rhizobacteria associated with sorghum. Treatment of S. hermonthica seeds with isolates E19G12, E29G2b and E19G10 resulted in the lowest S. hermonthica seed germination of 0%, 1%, and 2.7% respectively, which were significantly lower than any of the treatments. Mean germination percentage ranged from 9 to 59.7 and 0 to 27 in the absence and presence of host plants, respectively. The results showed a statistically significant germination inhibition (p < 0.001). Finally, the most effective isolates were shortlisted, E19G6a, E19G9, E19G6b, E19G10, E19B, E19G12, E29G2a, and E29G7 were morphologically and biochemically identified to belong to the genera of Pseudomonas, Klebssiella, Bacillus and Entrobacter. The results of the study demonstrated the existence of promising soil-borne bacteria that could be exploited as bioherbicides to control Striga infestation on sorghum provided that broader samples from various parts of the country are explored.

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]

Abstract Plants that produce allelopathic compounds against weeds have emerged as a potential solution for the development of ecologically correct bioherbicides. Talinum triangulare is noteworthy in this regard, as its phytochemical composition encompasses flavonoids, alkaloids and other metabolites that can be used to develop inhibitory weed growth solutions. Lactuca sativa (lettuce) has been widely applied as a bioindicator species for bioherbicides and several chemicals, animal waste, water and soil quality, and atmospheric contamination, among others. In this context, this study aimed to assess the potential allelopathic effect of aqueous T. triangulare extracts on the development of L. sativa seedlings. A completely randomized design employing a 2x4 factorial scheme (shoot and root extracts) x the concentration of each extract (0, 2.5, 5, 7.5%) was applied, comprising four replications. Lactuca sativa seeds were sown on germitest papers soaked with the extracts in a germination chamber at 20°C. Physiological seed evaluations comprising the germination test, where normal and abnormal seedlings are counted on the seventh day after sowing, first normal seedling counts on the fourth day after sowing, and seedling and root length measurements. At the end of the germination test, L. sativa seedlings were separated for morphoanatomical characterizations and chlorophyll a fluorescence analyses. The T. triangulare extracts significantly influenced L. sativa root growth, with shoot extract exposure leading to more abnormal plants and lower root lengths at increasing concentrations and compared to the root extract. Root extract exposure led to evident cellular changes and lower non-photochemical quenching and unregulated dissipation quantum yields at a 5% exposure dose compared to shoot extract exposure. These findings suggest that both aqueous T. triangulare root and shoot extracts from 5% exposure doses exhibit high potential as bioherbicides, acting directly on plant structure, anatomy, quality, size and physiology.

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.

Biological control of undesirable weeds associated with crop cultivation is a sustainable approach that can reduce chemical herbicide dependence. The current study aimed to assess the bio-herbicidal potential of the donor species Ononis vaginalis Vahl. on germination efficiency as well as various growth and physiological parameters of the recipient species Rumex dentatus L., a major broad bean pest (Vicia faba L.). To assess the greatest inhibitory allelopathic effect on the recipient species in mixed (Rumex dentatus L. and Vicia faba L.) and pure cultures (each one separately), two experiments were conducted under laboratory conditions. A Petri dish experiment using O. vaginalis shoot aqueous extract (5%, 10%, 20%, and 40%) and a pot experiment using O. vaginalis shoot crude powder (1%, 2%, 5%, and 10%) were conducted to investigate its biological activity on some growth and physiological parameters of both crop and weed species. O. vaginalis underwent a general phytochemical screening that revealed a high production of allelochemicals, which are secondary metabolites and may have a function like that of natural herbicides. The result showed that the germination of V. faba seeds in both pure and mixed cultures was not significantly affected by low levels of O. vaginalis shoot aqueous extract treatments in pure and mixed cultures, in contrast, those recorded for R. dentatus gradually dropped as levels of O. vaginalis increased in both cultures. Results recorded a significant increase in total phenolics of V. faba shoots and roots under different treatments, except at the high concentrations of crude powder at the donor species level (5 and10%). A reduction in the total phenolic and flavonoid fractions was observed in R. dentatus roots under varying concentration treatments. Conversely, under high concentration treatments, flavonoids decreased in the roots of the mixed culture of R. dentatus but increased in the shoots. In conclusion, allelopathy can be used to suppress weeds in field crops. The study confirmed the use of O. vaginalis into current weed control techniques. O. vaginalis could be explored further for weed suppression in the field.

Weeds decrease yield in crops through competition for water, nutrients, and light. Due to the circumstances mentioned above and the challenge of the emergence of herbicide-resistant weeds, developing sustainable alternatives becomes imperative. Plant extracts formulated into nano- and micro-encapsulates (NPs) emerge as a viable option for weed management. The objectives of this study were to identify phytochemical compounds within the ethanolic extracts of Carya illinoinensis, Ruta graveolens, and Solanum rostratum; determine their pre-emergence herbicidal activity on the indicator plants Sorghum bicolor and Phaseolus vulgaris; produce and characterize NPs with plant extracts; and assess their phytotoxicity under greenhouse conditions. The extracts were provided by Greencorp Biorganiks de México. Phytochemicals were identified through colorimetric assays and HPLC-MS, while pre-emergence tests were conducted in vitro, assessing concentrations of 12.5, 25, and 50% for each extract. NPs were synthesized using the ionotropic pre-gelation method, with size, zeta potential, and encapsulation efficiency (EE) being characterized. Finally, post-emergence tests were carried out in a greenhouse with seedlings. Compounds belonging to the hydroxycinnamic acid, flavonol, methoxyflavonol, hydroxybenzoic acid, methoxyflavone, tyrosol, stilbene, and lignan families were identified in all extracts. The pre-emergence herbicidal activity was observed for all extracts, with germination percentages ranging from 0 to 41% in both indicator plants. NPs exhibited sizes between 290 and 345 nm, zeta potentials ranging from −30 to −35 mV, and EE up to 94%. Finally, enhanced herbicidal activity was observed with plant extract NPs, with the species S. bicolor being more susceptible. NPs containing plant extracts are a viable option for bioherbicide production; however, continued research is necessary to refine formulations and enhance efficacy. [ABSTRACT FROM AUTHOR]

Several Acacia species are aggressive invaders outside their native range, often occupying extensive areas. Traditional management approaches have proven to be ineffective and economically unfeasible, especially when dealing with large infestations. Here, we explain a different approach to complement traditional management by using the waste from Acacia management activities. This approach can provide stakeholders with tools to potentially reduce management costs and encourage proactive management actions. It also prioritizes potential applications of Acacia waste biomass for agriculture and forestry as a way of sequestering the carbon released during control actions. We advocate the use of compost/vermicompost, green manure and charcoal produced from Acacia waste, as several studies have shown their effectiveness in improving soil fertility and supporting crop growth. The use of waste and derivatives as bioherbicides or biostimulants is pending validation under field conditions. Although invasive Acacia spp. are banned from commercialization and cultivation, the use of their waste remains permissible. In this respect, we recommend the collection of Acacia waste during the vegetative stage and its subsequent use after being dried or when dead, to prevent further propagation. Moreover, it is crucial to establish a legal framework to mitigate potential risks associated with the handling and disposal of Acacia waste.

The objective of this study was to determine the effects of Murraya koenigii (curry leaf) aqueous extract on the seed germination and growth of two crops and their associated weeds (Anagallis arvensis, Poa annua, Lepidium didymum, and Vicia sativa). Wheat (Triticum aestivum) and Chickpea (Cicer arietinum) seeds were soaked in solutions containing 2, 4, 6, 8, and 10% concentrations of aqueous extracts of M. koenigii leaves, while distilled water was used as a control. Higher concentrations of the extract significantly increased the percentage of germination inhibition and decreased the radicle length and plumule length of both crops compared to the control. It was interesting to find that the pot-based experiment had no influence on the shoot length, plant dry mass, chlorophyll, carotenoid, proline, or protein content, stomatal conductance, or photosynthetic and transpiration rate in either crop. Similarly, in comparison to the control, the activity of antioxidant enzymes (peroxidase (PER), superoxide dismutase (SOD), and catalase (CAT)) had no significant influence. Soil physiochemical parameters and weed shoot growth were also investigated. In a Petri plate experiment, 6, 8, and 10% concentrations inhibited germination of both crops. In comparison, in the pot experiment, the growth of both crops was significant at lower concentrations, and 1% aqueous extract of M. koenigii was reported to be lethal to weeds without affecting the soil physiochemical properties. Based on the results of this study, it can be inferred that the reduced germination rate of the tested species after treatment with the extract could be attributed to damage caused by the extracts to the membrane system of the seed. This study concluded that an aqueous leaf extract of M. koenigii can inhibit the growth of weeds without affecting the germination, growth, photosynthetic, and biochemical properties of C. arietinum and T. aestivum or the physiochemical properties of soil; thus, it may be a potential candidate for the development of new bioherbicides. [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]

Biological control refers to the use of living beneficial organisms as well as the products of their metabolism in pest control. Weed plants are indispensable companions of cultivated plants, in which they cause substantial damage. Organic food production, human health care and environmental preservation impose a need for the production and application of bioherbicides, particularly in organic systems of plant production. Plant pathogens have significant potential as biological agents in weed control. The aim of the present study was to indicate the most important properties of the weed biological control system, with particular emphasis on the use of fungi-based bioherbicides. According to the organism they suppress, biopesticides are classified into bioinsecticides, biofungicides, bioherbicides, etc. Weed control using plant pathogens can be performed in three ways, by classical, conservation and augmentative biological control. Bioherbicides were initially introduced to the market in 1980, and the majority of them were fungi-based bioherbicides. The most common fungi included in bioherbicides belong to the genera Alternaria, Colletotrichum, Cercospora, Fusarium, Phomopsis, Phytophthora, Phoma, Puccinia, etc. The studies, development and final commercialisation of fungi as biological control agents face many obstacles, ranging from basic biological facts to social and economic factors. There are also challenges in the production, formulation process, environmental friendliness, duration of herbicidal action, and expensive and time-consuming registration procedures. Considering the success in weed suppression with fungi-based bioherbicides, the global market is still dominated by chemical companies manufacturing synthetic herbicides, while there are no such products on the Serbian market yet.

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]

Weeds such as parasite plants are one of the most serious pests that farmers are forced to combat since the development of agriculture using different methods including mechanic and agronomy strategies. These pests have generated significant losses of agrarian and herding production, constituting a serious impediment for agricultural activities in reforestation practices and in important infrastructures. All these serious problems have induced the expansive and massive use of synthetic herbicides, which represents one of the main cause of environmental pollution, as well as serious risks for human and animal health. An alternative environmental friendly control method could be the use of bioherbicides based on suitably bioformulated natural products, of which the main ones are fungal phytotoxins. This review covers the literature from 1980 to the present (2022) and concerns fungal phytotoxins with potential herbicidal activity in order to obtain their efficacy as bioherbicides for practical application in agriculture. Furthermore, some bioherbicides based on microbial toxic metabolites are commercially available, and their application in field, mode of action and future perspectives are also discussed. [ABSTRACT FROM AUTHOR]

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.

Soil plays a primary role in the activity of plant allelochemicals in natural and agricultural systems. In this work, we compared the phytotoxicity of three natural hydroxycoumarins (umbelliferone, esculetin, and scopoletin) to different model plant species (Lactuca sativa, Eruca sativa, and Hordeum vulgare) in Petri dishes, and then selected the most phytotoxic compound (umbelliferone) to assess how its adsorption and dissipation in two distinct soils affected the expression of its phytotoxic activity. The root growth inhibitory effect of umbelliferone was significantly greater than that of esculetin and scopoletin, and the dicot species (L. sativa and E. sativa) were more sensitive to the hydroxycoumarins than the monocot species (H. vulgare). For all three plant species tested, the phytotoxicity of umbelliferone decreased in the following order: soilless (Petri dishes) > soil 1 > soil 2. In soil 2 (alkaline), umbelliferone displayed negligible adsorption (Kf < 0.01) and rapid biodegradation (t1/2 = 0.2–0.8 days), and its phytotoxicity was barely expressed. In soil 1 (acid), umbelliferone displayed enhanced adsorption (Kf = 2.94), slower biodegradation (t1/2 = 1.5–2.1 days), and its phytotoxicity was better expressed than in soil 2. When the microbial activity of soil 2 was suppressed by autoclaving, the phytotoxicity of umbelliferone, in the presence of soil, became similar to that observed under soilless conditions. The results illustrate how soil processes can reduce the allelopathic activity of hydroxycoumarins in natural and agricultural ecosystems, and suggest scenarios where the bioactivity of hydroxycoumarins may be better expressed. [ABSTRACT FROM AUTHOR]

This is the first study to evaluate the phytotoxic activity of three phenolic compounds present in the essential oil of the labdanum of Cistus ladanifer, an allelopathic species of the Mediterranean ecosystem. Propiophenone, 4′-methylacetophenone, and 2′,4′-dimethylacetophenone slightly inhibit total germination and radicle growth of Lactuca sativa, and they strongly delay germination and reduce hypocotyl size. On the other hand, the inhibition effect of these compounds on Allium cepa was stronger on total germination than on germination rate, and radicle length compared to hypocotyl size. The position and number of methyl groups will affect the efficacy of the derivative. 2′,4′-dimethylacetophenone was the most phytotoxic compound. The activity of the compounds depended on their concentration and presented hormetic effects. In L. sativa, on paper, propiophenone presented greater inhibition of hypocotyl size at greater concentrations, with IC50 = 0.1 mM, whereas 4′-methylacetophenone obtained IC50 = 0.4 mM for germination rate. When the mixture of the three compounds was applied, in L. sativa, on paper, the inhibition effect on total germination and the germination rate was significantly greater compared to the effect of the compounds when they were applied separately; moreover, the mixture inhibited radicle growth, whereas propiophenone and 4′-methylacetophenone did not exert such effect when applied separately. The activity of the pure compounds and that of the mixture also changed based on the substrate used. When the trial was conducted in soil, the separate compounds delayed the germination of the A. cepa to a greater extent compared to the trial on paper, although they stimulated seedling growth. In soil, L. sativa against 4′-methylacetophenone also showed the opposite effect at low concentrations (0.1 mM), with stimulation of germination rate, whereas propiophenone and 4′-methylacetophenone presented a slightly increased effect. [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]

This study explores how hydroalcoholic extracts of Campomanesia lineatifolia R. and P. seeds affect the germination and viability of seeds from two weeds, Rumex crispus and Amaranthus hybridus. The phenolic compounds were initially characterized using ultra-high-performance liquid chromatography. In seeds sown in Petri dishes, four concentrations of hydroalcoholic extracts (0%, 3%, 6%, and 9% w/v) were used for single and continuous applications. The mean germination speed, mean germination time, germination percentage, and seed viability were evaluated. Epigallocatechin gallate, quercetin-3-glucoside, epicatechin gallate, ursolic acid, epigallocatechin, and trans-cinnamic acid were the main compounds discovered in that order. Notably, while the germination percentages of both species were reduced with a single application (38.5% for R. crispus and 52% for A. hybridus), they were reduced by 76.2% and 58.34% with a continuous application, respectively. A delay in germination was also observed, which produced changes in germination speed throughout the experiment. With a 9% application, the number of nonviable seeds of R. crispus increased by 40.53%, whereas in A. hybridus, viability decreased by at least 70.8%. Overall, the phenolic compounds in C. lineatifolia extract are thought to inhibit the germination process of the evaluated species. [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]

Concerns about food safety issues have put considerable pressure on pesticide producers in Europe and worldwide to reduce the levels of pesticide residues in food. The aim of this work is to assess the use of traditional pesticides and their effects, to present perspectives in this field and to identify regulatory needs for their use and implementation. The work is based on a systematic review in which the research problem was defined, primary sources were selected and critically appraised, data were collected, analysed and evaluated, and conclusions were formulated. The state of the pesticide market and the current legal requirements for risk assessment in relation to exposure to chemical substances were reviewed. Food safety issues are presented through the prism of pesticide residues in food. Their widespread use and considerable persistence have made them ubiquitous in the natural environment and their residues pose a threat to the environment and to human and animal health. It has been shown that the most important factor influencing the search for new tools to control diseases and pests of crops is the progressive development of resistance of these populations to currently used pesticides. Various alternatives to the phasing out of synthetic pesticides in the form of natural products are therefore being developed to support the development of the natural products market. Natural phytotoxins can be used as herbicides, but it is more effective to use bioherbicides as templates for synthetic herbicides. They can also be used to discover new modes of action and molecular targets for future herbicides. [ABSTRACT FROM AUTHOR]

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Over the past few years, both producers and consumers have become increasingly interested in organic farming because conventional agriculture relies so heavily on the use of synthetic pesticides, thus causing environmental pollution. Weeds, as inevitable "companions" of cultivated plants, represent a major, everlasting issue in plant production. As organic plant production is legally regulated, the control of undesirable plants such as weeds is further complicated. Using the relevant literature, the purpose of this study is to survey the existing weed control methods in organic crop production. In order to be certified, organic plants have to be grown in the farming system without the application of synthetic herbicides and other chemicals that are commonly used in conventional production. This means that crop growers have to apply non-chemical, alternative methods of weed suppression, i.e. weed control based on the combination of cropping practices, mechanical control, and the use of bioherbicides. There is a large number of plant extracts with bioherbicidal activity, the effect of which is mostly attributed to the biological phenomenon of allelopathy, rendering such weed control sustainable, inexpensive, and environmentally friendly. Although bioherbicides are successfully used in organic farming worldwide, there are no registered bioherbicides in Serbia to date (according to the data of the Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia). Both organic producers and experts should raise awareness of the importance of successful weed control to the health of cultivated plants, soil, beneficial organisms, and the entire ecosystem, which requires further research attention.

Weeds decrease yield in crops through competition for water, nutrients, and light. Due to the circumstances mentioned above and the challenge of the emergence of herbicide-resistant weeds, developing sustainable alternatives becomes imperative. Plant extracts formulated into nano- and micro-encapsulates (NPs) emerge as a viable option for weed management. The objectives of this study were to identify phytochemical compounds within the ethanolic extracts of Carya illinoinensis, Ruta graveolens, and Solanum rostratum; determine their pre-emergence herbicidal activity on the indicator plants Sorghum bicolor and Phaseolus vulgaris; produce and characterize NPs with plant extracts; and assess their phytotoxicity under greenhouse conditions. The extracts were provided by Greencorp Biorganiks de México. Phytochemicals were identified through colorimetric assays and HPLC-MS, while pre-emergence tests were conducted in vitro, assessing concentrations of 12.5, 25, and 50% for each extract. NPs were synthesized using the ionotropic pre-gelation method, with size, zeta potential, and encapsulation efficiency (EE) being characterized. Finally, post-emergence tests were carried out in a greenhouse with seedlings. Compounds belonging to the hydroxycinnamic acid, flavonol, methoxyflavonol, hydroxybenzoic acid, methoxyflavone, tyrosol, stilbene, and lignan families were identified in all extracts. The pre-emergence herbicidal activity was observed for all extracts, with germination percentages ranging from 0 to 41% in both indicator plants. NPs exhibited sizes between 290 and 345 nm, zeta potentials ranging from −30 to −35 mV, and EE up to 94%. Finally, enhanced herbicidal activity was observed with plant extract NPs, with the species S. bicolor being more susceptible. NPs containing plant extracts are a viable option for bioherbicide production; however, continued research is necessary to refine formulations and enhance efficacy.

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]

This current investigation was undertaken both in laboratory and glasshouse for documentation and quantification of phytochemicals from different parts of the parthenium (Parthenium hysterophorus L.) plant through LC-MS and HPLC to study their effect on two crops namely, Bambara groundnut (Vigna subterranean L.) and maize (Zea mays L.), and six different types of weed e.g., Digitaria sanguinalis, Eleusine indica, Ageratum conyzoides, Cyperus iria, Euphorbia hirta, and Cyperus difformis. The parthenium methanolic leaf extracts at 25, 50, 75, and 100 g L−1 were sprayed in the test crops and weeds to assess their physiological and biochemical reactions after 6, 24, 48, and 72 h of spraying these compounds (HAS). The LC-MS analysis confirmed seven types of phytochemicals (caffeic acid, ferulic acid, vanillic acid, parthenin, chlorogenic acid, quinic acid, and p-anisic acid) in the parthenium leaf extract that were responsible for the inhibition of tested crops and weeds. From the HPLC analysis, higher amounts in leaf methanol extracts (40,752.52 ppm) than those of the stem (2664.09 ppm) and flower extracts (30,454.33 ppm) were recorded. Parthenium leaf extract at 100 g L−1 had observed higher phytotoxicity on all weed species except C. difformis. However, all crops were found safe under this dose of extraction. Although both crops were also affected to some extent, they could recover from the stress after a few days. The photosynthetic rate, transpiration rate, stomatal conductance, carotenoid and chlorophyll content were decreased due to the application of parthenium leaf extract. However, when parthenium leaf extract was applied at 100 g L−1 for 72 h, the malondialdehyde (MDA) and proline content were increased in all weeds. Enzymatic antioxidant activity (e.g., superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) contents) were also elevated as a result of the sprayed parthenium leaf extract. The negative impact of physiological and biochemical responses as a consequence of the parthenium leaf extract led the weed species to be stressed and finally killed. The current findings show the feasibility of developing bioherbicide from the methanolic extract of parthenium leaf for controlling weeds, which will be cost-effective, sustainable, and environment friendly for crop production during the future changing climate. [ABSTRACT FROM AUTHOR]

Weeds are a serious threat to crop production as they interfere with the crop growth and development and result in significant crop losses. Weeds actually cause yield loss higher than any other pest in crop production. As a result, synthetic herbicides have been widely used for weed management. Heavy usage of synthetic herbicides, however, has resulted in public concerns over the impact of herbicides on human health and the environment. Due to various environmental and health issues associated with synthetic herbicides, researchers have been exploring alternative environmentally friendly means of controlling weed. Among them, incorporating allelopathy as a tool in an integrated weed management plan could meaningfully bring down herbicide application. Allelopathy is a biological phenomenon of chemical interaction between plants, and this phenomenon has great potential to be used as an effective and environmentally friendly tool for weed management in field crops. In field crops, allelopathy can be applied through intercropping, crop rotation, cover crops, mulching and allelopathic water extracts to manage weeds. Accumulating evidence indicates that some plant species possess potent allelochemicals that have great potential to be the ecofriendly natural herbicides. This review is intended to provide an overview of several allelopathic species that release some form of the potent allelochemical with the potential of being used in conventional or organic agriculture. Further, the review also highlights potential ways allelopathy could be utilized in conventional or organic agriculture and identify future research needs and prospects. It is anticipated that the phenomenon of allelopathy will be further explored as a weed management tool, and it can be a part of a sustainable, ecological, and integrated weed management system. [ABSTRACT FROM AUTHOR]

Within integrated pest management programs, biological control of unwanted plants has remarkable capacity to provide viable, effective, and economic control of weeds. When using bio-herbicides, crop production and quality improve with virtually no damage to the ecosystem. Bioherbicides are target-specific, destroy only selected weeds that have been sprayed for and do not cause harm to non-target plants. Bio-herbicides can be quickly incorporated into weed control programs, which can reduce chemical herbicide dependence. We are also raising the chance of environmental pollution by pesticides. There are only a few bio-herbicides available on commercial bases although work began earlier in the 1940s. Sources of commercialized bioherbicides include Phytophthora palmivora (Devine), Collectotrichum gleosporiodes (Collego), Colletotrichum gloeosporioides (Binomial) and Streptomyces viridochromogenes (Bialaphos and Glufosinate). Virulence for pathogens and their environmental requirement are major constraints for bioherbicide development. Specific bio-herbicides should be useful in finding position in irrigated fields, wildlife while thriving weeds with pests or resistant weed control. [ABSTRACT FROM AUTHOR]

Cuscuta campestris is a parasitic weed species with noxious effects in broadleaf crops worldwide. The control of Cuscuta in the majority of crops affected is limited or non-existing. We tested, for the first time, the effect of eighteen metabolites in in vitro-grown Cuscuta seedlings. We found that 2-benzoxazolinone, hydrocinnamic acid and pisatin caused the strongest inhibition of seedling growth. In addition to seedling growth, pisatin caused necrosis of the Cuscuta seedling, occurring mostly at the seedling shoot. Scopoletin and sesamol treatments caused toxicity, observed as a black staining, only at the Cuscuta root apices, while caffeic acid, ferulic acid and vanillic acid caused toxicity, observed as brown staining, in the root apices. The structure–activity relationships in four structural derivatives of 2-benzoxazolinone, and five structural derivatives of hydrocinnamic acid, were also studied. The identification of new herbicidal modes of action against Cuscuta is the first step in creating new alternatives to sustainable chemical control of parasitic weeds. [ABSTRACT FROM AUTHOR]

Allelopathic effects of different plant allelochemicals have become the focus of studies that aim to determine new pesticidal compounds. Plant extracts with different chemical compositions can be obtained using different methods of extraction, whereas studies dealing with allelopathic properties use biotests to obtain fast and precise results. Such studies were undertaken after noticing the allelopathic effects of industrial hemp (Cannabis sativa L.) on the surrounding crops. Trials that involve the application of hemp extracts obtained by different methods resulted in determining the hemp allelopathic effects on Stellaria media (L.)Scop., Beta vulgaris ssp. vulgaris var. vulgaris, Lupinus albus L., corn (Zea mays L.), Cyperus rotundus L., Matricaria recutita L., Lepidium sativum L., lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), rye (Secale cereal M. Bieb.), Ambrosia artemisiifolia L., Chenopodium album L., and Sorghum halepense L..

Within integrated pest management programs, biological control of unwanted plants has remarkable capacity to provide viable, effective, and economic control of weeds. When using bio-herbicides, crop production and quality improve with virtually no damage to the ecosystem. Bioherbicides are target-specific, destroy only selected weeds that have been sprayed for and do not cause harm to non-target plants. Bio-herbicides can be quickly incorporated into weed control programs, which can reduce chemical herbicide dependence. We are also raising the chance of environmental pollution by pesticides. There are only a few bio-herbicides available on commercial bases although work began earlier in the 1940s. Sources of commercialized bioherbicides include Phytophthora palmivora (Devine), Collectotrichum gleosporiodes (Collego), Colletotrichum gloeosporioides (Binomial) and Streptomyces viridochromogenes (Bialaphos and Glufosinate). Virulence for pathogens and their environmental requirement are major constraints for bioherbicide development. Specific bio-herbicides should be useful in finding position in irrigated fields, wildlife while thriving weeds with pests or resistant weed control.

Weeds are a serious threat to crop production as they interfere with the crop growth and development and result in significant crop losses. Weeds actually cause yield loss higher than any other pest in crop production. As a result, synthetic herbicides have been widely used for weed management. Heavy usage of synthetic herbicides, however, has resulted in public concerns over the impact of herbicides on human health and the environment. Due to various environmental and health issues associated with synthetic herbicides, researchers have been exploring alternative environmentally friendly means of controlling weed. Among them, incorporating allelopathy as a tool in an integrated weed management plan could meaningfully bring down herbicide application. Allelopathy is a biological phenomenon of chemical interaction between plants, and this phenomenon has great potential to be used as an effective and environmentally friendly tool for weed management in field crops. In field crops, allelopathy can be applied through intercropping, crop rotation, cover crops, mulching and allelopathic water extracts to manage weeds. Accumulating evidence indicates that some plant species possess potent allelochemicals that have great potential to be the ecofriendly natural herbicides. This review is intended to provide an overview of several allelopathic species that release some form of the potent allelochemical with the potential of being used in conventional or organic agriculture. Further, the review also highlights potential ways allelopathy could be utilized in conventional or organic agriculture and identify future research needs and prospects. It is anticipated that the phenomenon of allelopathy will be further explored as a weed management tool, and it can be a part of a sustainable, ecological, and integrated weed management system.

The objective of this study was to determine the effects of Murraya koenigii (curry leaf) aqueous extract on the seed germination and growth of two crops and their associated weeds (Anagallis arvensis, Poa annua, Lepidium didymum, and Vicia sativa). Wheat (Triticum aestivum) and Chickpea (Cicer arietinum) seeds were soaked in solutions containing 2, 4, 6, 8, and 10% concentrations of aqueous extracts of M. koenigii leaves, while distilled water was used as a control. Higher concentrations of the extract significantly increased the percentage of germination inhibition and decreased the radicle length and plumule length of both crops compared to the control. It was interesting to find that the pot-based experiment had no influence on the shoot length, plant dry mass, chlorophyll, carotenoid, proline, or protein content, stomatal conductance, or photosynthetic and transpiration rate in either crop. Similarly, in comparison to the control, the activity of antioxidant enzymes (peroxidase (PER), superoxide dismutase (SOD), and catalase (CAT)) had no significant influence. Soil physiochemical parameters and weed shoot growth were also investigated. In a Petri plate experiment, 6, 8, and 10% concentrations inhibited germination of both crops. In comparison, in the pot experiment, the growth of both crops was significant at lower concentrations, and 1% aqueous extract of M. koenigii was reported to be lethal to weeds without affecting the soil physiochemical properties. Based on the results of this study, it can be inferred that the reduced germination rate of the tested species after treatment with the extract could be attributed to damage caused by the extracts to the membrane system of the seed. This study concluded that an aqueous leaf extract of M. koenigii can inhibit the growth of weeds without affecting the germination, growth, photosynthetic, and biochemical properties of C. arietinum and T. aestivum or the physiochemical properties of soil; thus, it may be a potential candidate for the development of new bioherbicides.

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.

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]

Cuscuta species are obligate parasitic plants that infect the stems of a wide range of hosts including many crop and weed species causing severe agricultural problems. Using in vitro experiments to screen organic extracts prepared from fifteen autotrophic weed species found in agricultural fields infested with Cuscuta campestris, we have identified for the first time a strong phytotoxic activity in Conyza bonariensis extract against C. campestris. Additional pot experiments revealed that seven day-old Cuscuta seedlings had reduced capacity to coil and properly attach on Conyza plants, leading to reduced parasitic weed infection. Via activity-guided fractionation of Conyza extracts, we isolated and identified the acetylenic furanone (4Z)-lachnophyllum lactone as the major active component, with a concentration required to achieve reduction of 50% Cuscuta seedling growth (IC50) of 24.8 µg/mL. The discovery of (4Z)-lachnophyllum lactone bioactivity could aid the development of efficient and sustainable management strategies for C. campestris, whose control is limited or non-existent. [ABSTRACT FROM AUTHOR]

Plant monoterpenes have received attention for their ecological functions and as potential surrogates for synthetic herbicides, but very little is known about the processes that govern their behavior in the soil environment, and even less about the possible enantioselectivity in the functions and environmental behavior of chiral monoterpenes. We characterized the adsorption and dissipation of the two enantiomers of the chiral monoterpene pulegone in different soils, and their phytotoxicity to different plant species through Petri dish and soil bioassays. R- and S-pulegone displayed a low-to-moderate non-enantioselective adsorption on the soils that involved weak interaction mechanisms. Soil incubation experiments indicated that, once in the soil, R- and S-pulegone are expected to suffer rapid volatilization and scarcely enantioselective, biodegradation losses. In Petri dishes, the phytotoxicity of pulegone and its enantioselectivity to Lactuca sativa, Hordeum vulgare, and Eruca sativa was species-dependent. Lactuca sativa was the most sensitive species and showed higher susceptibility to S- than to R-pulegone. Biodegradation and volatilization losses greatly reduced the phytotoxic activity of S-pulegone applied to soil, but the addition of a highly-adsorptive organoclay stabilized the monoterpene and increased its phytotoxic effect. Stabilization by adsorption may represent an important mechanism by which the bioactivity of plant monoterpenes in soils can be increased. [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]

With allelopathic composts, potential merits for preventing initial weed infestations have been observed in crop transplantation. However, previous studies have rarely investigated whether high temperatures, generated during composting, decrease allelopathic ability. This study evaluated the thermal allelopathic effect of two coniferous plants (Pinus densiflora and P. koraiensis) on Brassica napus germination and seedling growth using their characterized allelochemical destinations. The 90 °C dry treatment of P. densiflora extract exhibited stronger inhibitory effect on germination than its 30 °C dry treatment. In a range from 0.25 to 1 mg mL−1, the germination rate was decreased to 38.1 and 64.3% of control with P. densiflora extract dried at 90 and 30 °C, respectively. However, P. koraiensis showed potent inhibition of the germination process with no statistical difference in inhibitory effects regardless of the dry temperature. Regarding B. napus seedling root growth, the allelopathic effects of aqueous extracts of both conifers were not reduced with the 90 °C treatment, but it was lost in seedling shoot growth. GC-MS/MS confirmed that high temperature treatment drastically decreased volatile contents to 53.2% in P. densiflora, resulting in reduced allelopathic abilities. However, a relatively lower decrease to 83.1% in volatiles of P. koraiensis accounts for less loss of the root-specific inhibitory effect on B. napus seedlings even after 90 °C treatment. Foliar tissues of both conifers with species-specific thermal resistance have potentially valuable functions regarding allelopathic use in horticultural compost processing ingredients, demonstrating their weed control ability during the early cultivation season where crops are transplanted in the facilitated area. [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]

This is the first study to evaluate the phytotoxic activity of three phenolic compounds present in the essential oil of the labdanum of Cistus ladanifer, an allelopathic species of the Mediterranean ecosystem. Propiophenone, 4′-methylacetophenone, and 2′,4′-dimethylacetophenone slightly inhibit total germination and radicle growth of Lactuca sativa, and they strongly delay germination and reduce hypocotyl size. On the other hand, the inhibition effect of these compounds on Allium cepa was stronger on total germination than on germination rate, and radicle length compared to hypocotyl size. The position and number of methyl groups will affect the efficacy of the derivative. 2′,4′-dimethylacetophenone was the most phytotoxic compound. The activity of the compounds depended on their concentration and presented hormetic effects. In L. sativa, on paper, propiophenone presented greater inhibition of hypocotyl size at greater concentrations, with IC50 = 0.1 mM, whereas 4′-methylacetophenone obtained IC50 = 0.4 mM for germination rate. When the mixture of the three compounds was applied, in L. sativa, on paper, the inhibition effect on total germination and the germination rate was significantly greater compared to the effect of the compounds when they were applied separately; moreover, the mixture inhibited radicle growth, whereas propiophenone and 4′-methylacetophenone did not exert such effect when applied separately. The activity of the pure compounds and that of the mixture also changed based on the substrate used. When the trial was conducted in soil, the separate compounds delayed the germination of the A. cepa to a greater extent compared to the trial on paper, although they stimulated seedling growth. In soil, L. sativa against 4′-methylacetophenone also showed the opposite effect at low concentrations (0.1 mM), with stimulation of germination rate, whereas propiophenone and 4′-methylacetophenone presented a slightly increased effect.

Weeds such as parasite plants are one of the most serious pests that farmers are forced to combat since the development of agriculture using different methods including mechanic and agronomy strategies. These pests have generated significant losses of agrarian and herding production, constituting a serious impediment for agricultural activities in reforestation practices and in important infrastructures. All these serious problems have induced the expansive and massive use of synthetic herbicides, which represents one of the main cause of environmental pollution, as well as serious risks for human and animal health. An alternative environmental friendly control method could be the use of bioherbicides based on suitably bioformulated natural products, of which the main ones are fungal phytotoxins. This review covers the literature from 1980 to the present (2022) and concerns fungal phytotoxins with potential herbicidal activity in order to obtain their efficacy as bioherbicides for practical application in agriculture. Furthermore, some bioherbicides based on microbial toxic metabolites are commercially available, and their application in field, mode of action and future perspectives are also discussed.