Plant-Based Bioherbicides: Review of Eco-Friendly Strategies for Weed Control in Organic Bean and Corn Farming

Abstract

Weeds are among the primary factors limiting corn and bean productivity, accounting for up to 30% of yield losses. Although chemical herbicides remain the predominant weed control strategy, their toxicity poses significant risks to human health and the environment. In response, organic agriculture has gained prominence as a more sustainable production system, with an increasing interest in alternative weed management approaches. Plants that produce allelopathic compounds capable of inhibiting the growth of unwanted species have emerged as promising sources of natural bioherbicides. While recent reviews have primarily focused on bioherbicides derived from microorganisms, a notable gap remains regarding the production and application of bioherbicides based on plant extracts. This review addresses this gap by summarizing current knowledge on the use of plant extracts for weed control in corn and bean cultivation. It discusses extraction methods, key plant species and active compounds, target weed species, herbicidal effects, modes of action, and patented technologies. Promising plants include Cuscuta campestris, Cymbopogon citratus, Mentha spp., Eucalyptus spp., and Pinus spp., which are rich in bioactive compounds such as phenolics (i.e., flavonoids), quinones, aldehydes and ketones, lactones, terpenoids (i.e., 8-cineole), and steroids. Plant extract-based bioherbicides show promising potential as sustainable and effective alternatives for weed management in organic agriculture, contributing to reducing the synthetic chemical herbicides, avoiding more resistances of weeds resistance of control, and promoting more environmentally friendly agricultural practices.

1. Introduction

Corn and beans are primary crops widely used in human nutrition. Corn is also utilized in animal feed, such as for poultry and swine. In Brazil, the production of beans and corn in the 2023/2024 harvest reached 3.25 and 114.14 million tons, respectively, and estimates for the 2024/2025 harvest are 3.17 and 128.30 million tons [1]. Along with extensive crop production, there is widespread use of herbicides. One of the primary challenges in grain cultivation is the presence of weeds that compete with crops, potentially reducing yields. The losses caused by weeds account for approximately 34% of total crop losses, which is higher than those caused by other factors, such as diseases and insects [2]. Therefore, the primary method of control is based on traditional herbicides. However, herbicides pose environmental problems because they can be toxic to humans and animals. Furthermore, their widespread use can lead to the development of resistant plants.

Alternatives for weed control have been sought using bioherbicides, aiming for sustainable agriculture with reduced risks to human health and the environment. One alternative is the use of naturally derived products formulated from plant extracts or microorganisms, designed to control weeds [3,4]. They are natural products that align with the goals of organic farming [5,6].

Among the bioherbicides available in the global market, the majority are formulated from microorganisms, specifically fungi. Bioherbicides based on plant extracts are still relatively unexplored. Although a few bioherbicides based on plant extracts are currently registered in the global market, studies have demonstrated the potential of various plant extracts in inhibiting the germination and development of weeds through allelopathic compounds [4,7].

Recent review articles focus on bioherbicides derived from microorganisms. However, there is a lack of reviews highlighting the production and use of bioherbicides from plant extracts that infest corn and beans. This review aims to present and discuss methods for controlling weeds in corn and bean crops using bioherbicides produced from plant extracts. It also covers the main techniques for obtaining and processing these extracts. The main conclusion and practical applications are presented, highlighting that various plants can be sources of metabolites to formulate bioherbicides for controlling common weeds in bean and corn crops, offering an alternative for organic agriculture.

2. Methodology of Review Preparation

This study presents bioinputs as an alternative to decreasing the extensive use of agrochemicals. Bioherbicides are highlighted, demonstrating their potential and the need for further research. To gather this information, a search for articles using plant extracts for weed control was conducted in the databases ScienceDirect, SpringerLink, and Google Scholar, using the following keywords: “bioinputs”, “bioherbicides”, “plant extracts”, “weeds”, “organic bean”, “organic corn”, and “organic farming”. Articles from 2013 to 2025 were selected. From 2013 to 2020 and 2021 to 2023, articles with more than 10 and 5 citations, respectively, were chosen. All articles published in 2024 and 2025 were included for review (Figure 1). Similarly, patent searches were performed using the keywords “plant extracts,” “bioherbicide,” “weeds,” “organic bean,” “organic corn,” and “organic farming” on the Espacenet (https://worldwide.espacenet.com/) (accessed on 29 April 2025), WIPO (https://www.wipo.int/portal/en/index.html) (accessed on 29 April 2025), and INPI (https://www.gov.br/inpi/pt-br/servicos/patentes) (accessed on 16 May 2025) platforms.

From this information, the most relevant data were considered based on the study’s objective. As the study aimed to present bioherbicides as an alternative for use in organic bean and corn crops, information was selected on the main weeds that infest these crops, bioinputs that can be used to control pests in these crops, plants with bioherbicidal potential that have been tested on weeds that infest both crops, as well as the compounds responsible for causing phytotoxicity in weeds. Tables and figures were designed to present the most relevant information on the topic in a compiled and easy-to-understand manner. The figures were created using images obtained by the author as well as images from open-source platforms. The tables were prepared in Microsoft Word using data obtained from research conducted on platforms such as ScienceDirect, SpringerLink, and Google Scholar.

3. Main Weeds That Infest Corn and Beans

Weeds, also known as undergrowth, undesired plants, or unwanted herbs, are plants that grow spontaneously and are considered undesirable in a specific location due to traits such as high seed production, easy seed spread, resistance to frost and drought, and adaptability to different environments. These plants are often found in vacant lots, roadside verges, fields, and agricultural areas [8,9]. The presence of weeds in agricultural production areas is a major problem because they compete with crops for water, light, and nutrients, which leads to decreased crop yields [10].

Some weeds are commonly found in specific crops, while others may be common in more than one crop. Based on multiple references [11,12,13,14,15,16,17,18,19,20,21,22,23],

Table 1. Main weeds found in corn and bean crops.

Weed	Common Name	Family	Life Cycle	Morphological Group
Bidens pilosa	Blackjack	Asteraceae	Annual	Broadleaf
Digitaria spp.	Crabgrass	Poaceae	Annual	Grasses
Eleusine indica	Crowsfoot grass	Poaceae	Annual	Grasses
Amaranthus viridis	Caruru	Amaranthaceae	Annual	Broadleaf
Digitaria insularis	Sourgrass	Poaceae	Perennial	Grasses
Ipomoea purpurea	Morning-glory	Convolvulaceae	Annual	Broadleaf
Conyza bonariensis	Buva	Asteraceae	Annual	Broadleaf
Euphoria hirta	Saint Lucia grass	Commelinaceae	Annual	Broadleaf
Cenchrus echinatus	Crabgrass	Poaceae	Annual	Grasses
Cyperus rotundus	Tiririca	Cyperaceae	Perennial	Sedges
Amaranthus dubius	Thorn caruru	Amaranthaceae	Annual	Broadleaf
Parthenium hysterophos	Ragweed parthenium	Asteraceae	Annual	Broadleaf
Urochloa plantaginea	Alexandergrass	Poaceae	Annual	Grasses
Acanthospermum hispidum	Bristly starbur	Asteraceae	Annual	Broadleaf
Galinsoga parviflora	White Beggar	Asteraceae	Annual	Broadleaf
Urochloa decumbens	Brachiaria grass	Poaceae	Perennial	Grasses
Echinochloa colona	Jungle rice	Poaceae	Annual	Grasses
Ageratum conyzoides	St John’s wort	Asteraceae	Annual	Broadleaf
Senna obtusifolia	Forest-pasture	Fabaceae	Annual	Broadleaf
Portulaca oleracea	Purslane	Portulacaceae	Annual	Broadleaf
Sorghum halepense	Marsh grass	Poaceae	Perennial	Grasses
Alternanthea tenella	Joyweed	Amaranthaceae	Perennial	Broadleaf
Commelina benghalensis	Asiatic dayflower	Commelinaceae	Perennial	Broadleaf
Ambrosia artemisiifolia	Common ragweed	Asteraceae	Annual	Broadleaf
Spermacoce latifolia Aubl	Broadleaf Buttonweed	Rubiaceae	Annual	Broadleaf
Spermacoce verticillata	False buttonweed	Rubiaceae	Perennial	Broadleaf
Tridax procumbens	Coatbuttons	Asteraceae	Annual	Broadleaf
Cynodon dactylon	Coast-cross	Poaceae	Perennial	Grasses

presents the main weeds found in both corn and bean crops, or one of these crops, and Figure 2 shows some photos of these weeds. The majority of weeds belong to the Poaceae family.

Corn experiences an estimated 40% reduction in productivity due to weed presence in the crop, which is a larger loss compared to crops like rice (37%), cotton (36%), soybean (37%), and wheat (23%) [24]. Weeds cause a decrease in dry matter and both the number and weight of grains [25]. The period between four and seven weeks after corn sowing is when the crop is most affected by weeds [16].

India is a country with a diet predominantly based on three main crops (corn, wheat, and rice), in which the primary weeds found in summer in corn cultivation are Cyperus rotundus and Echinochloa colona. In winter, Brachiaria spp., Panicum coloratum, and Amaranthus viridis are seen [26]. In Pakistan, a study was conducted to assess the weeds in a corn production area, revealing the presence of 28 weed species belonging to 27 genera and 15 families. The highest number of species found belonged to the Poaceae and Amaranthaceae families [20].

In Brazil, an experiment conducted on corn culture revealed 24 weed species belonging to 10 different families. Among the weeds, the majority belonged to the Poaceae, Asteraceae, and Fabaceae families [19]. Khellin and visnagin furanochromones were reported as potential new bioherbicides with phytotoxic activities on Lemna pausicostata [27]. Extract of Ammi visnaga (L.) inhibited the growth and germination of weeds at 0.5 and 1 mM, like Lolium multiflorum, Echinocloa crus-galli, Digitaria sanguinalis, Setaria italica, Panicum sp., Ipomea sp., and Abutilon theophrasti [28].

The most common species of bean, Phaseolus vulgaris L., exhibits limited canopy growth, which makes it challenging to compete with weeds, leading to issues in this crop. This limitation can result in yield losses of up to 80% [21]. In a study conducted in Brazil, the presence of 16 weed species was identified in bean cultivation, distributed across 10 families. The family with the highest number of species was Asteraceae, among which Emilia fosbergii Nicolson, Acanthospermum hispidum DC., Tridax procumbens L., and Bidens pilosa L. were prominent. In the sequence, the Poaceae family included species such as Cenchrus echinatus L., Eleusine indica (L.) Gaertn, and Urochloa decumbens (Stapf) [29].

4. Organic Farming

Organic farming is defined as the cultivation of food in a sustainable manner, harmless to the environment and human health. To achieve this, a natural production technique refrains from using agrochemicals and respects the soil, water, and animals [5,30]. It is based on the pillars of: (i) health, prioritizing food quality; (ii) environment, aiming to produce without harming available natural resources; and (iii) sustainability, aiming to adopt ecologically sound practices to ensure a better world for future generations (Figure 3).

Organic farming has become an increasingly coveted sector for rural producers. It focuses on sustainable agriculture, delivering quality products free from any agrochemicals to the human population. This trend is emerging because people are increasingly seeking organic products that do not harm the environment or human health. To meet these demands, organic farming is gaining prominence. The use of bioinputs in agriculture is an alternative for controlling diseases, insects, nematodes, and weeds, thus providing plant nutrition. These inputs are of natural origin and can replace chemical products, emerging as a solution to various problems in this sector.

Compared to conventional foods, which use chemical pesticides and fertilizers during cultivation, organic foods contain lower levels or no substances harmful to humans, such as nitrates, heavy metals, or residues from chemical products and synthetic fertilizers. Analyses of the nutritional content and the health issues caused by conventionally grown and organic foods have shown that organic products differ from conventional products in terms of pesticide residues, sensory quality, and nutrients [31].

For this reason, the use of biological products in organic farming to help control pests, diseases, and weeds without harming the food is important. A study developed by O’Sullivan et al. [32] evaluated the use of bioherbicides produced from manuka oil for weed control in bell pepper, sweet popcorn, and tomato crops. As a result, weed control with manuka oil, mixed in a tank with Green Match EX, Weed Zap, or Weed Pharm, showed satisfactory results ranging from 90 to 95% control, resulting in a 20 to 25% improvement in overall weed control. Another study also shows that organic farming has a higher biodiversity of plants, insects, and birds compared to conventional farms. Spraying of traditional chemical products pollutes the habitat, thus causing less biodiversity [33].

4.1. Bioinputs

Bioinputs are alternatives to chemical products. They are produced from natural sources such as plants or microorganisms. They offer an alternative for the sustainable control of diseases, insects, nematodes, and weeds, being less toxic to the environment and living organisms. Unlike traditional chemical products that are registered per crop, bioinputs are registered based on the target. Hence, they can be classified as bioherbicides, biofungicides, bioinsecticides, bionematicides, biostimulants, and biofertilizers (Figure 4). The number of bioherbicides registered in certain countries is also shown in Figure 4.

In 2020, the Bioinputs Program of the Ministry of Agriculture, Livestock, and Supply (MAPA/Brazil) developed an app (https://play.google.com/store/apps/details?id=br.embrapa.bioinsumos (accessed on 11 June 2025)), aiming to facilitate the search for available bioinputs in the market. The app provides information on targets such as pests and diseases, available products to control them, companies that sell the products, the active ingredients, and the toxicological classification of the products. Among the products available for consultation in the app, solutions for pests and diseases affecting various crops, including rice, soybean, wheat, cotton, sugarcane, coffee, fruit trees, corn, and beans, are available. The app does not provide information about products for weed control because no registered bioherbicides are available in Brazil. However, at a global level, bioherbicides are available on the market, with the most promising ones formulated from fungi. Bioherbicides based on bacteria, viruses, and plant extracts are also available worldwide, although in smaller quantities. For instance, these bioherbicides are used to control Poa attebuata, Poa annua, Juglans nigra, Nassella trichotoma, Malva pusilla, Parkinsonia aculeata, Cyperus esculentus, and Prunus serotina [17], among others.

Table 2. Bioinputs for use in Brazil for pest and disease control, and bioherbicides available on the world market that can be used on bean and corn crops.

Bioinput Name *	Effect	Active Ingredient	Main Target
Excellence Mig-66	Bioinsecticide	Beauveria bassiana	Corn leafhopper
Bovenat	Bioinsecticide	Beauveria bassiana	Corn leafhopper
Isatrix	Bioinsecticide	Paecilomyces fumosoroseus	Corn leafhopper
Octane	Bioinsecticide	Isaria fumosorosea	Corn leafhopper
Canabovebio	Bioinsecticide	Beauveria bassiana, isolado IBCB 66	Corn leafhopper
Bv-Bio WP	Bioinsecticide	Beauveria bassiana, isolado IBCB 66	Corn leafhopper
Bravo	Bioinsecticide	Beauveria bassiana, isolado IBCB 66	Corn leafhopper
BTP 078-20	Bioinsecticide	Beauveria bassiana, isolado IBCB 66	Euschistus heros
Tricobio SC	Biofungicide	Trichoderma harzianum	White rot
Lepthure	Bioinsecticide	Bacillus thuringiensis	Pod caterpillar
BTP 010-19A	Biofungicide	Bacillus pumilus + Bacillus subtilis + Bacillus velezensis	White rot
Crisobase-E	Bioinsecticide	Chrysoperla externa	Green cereal aphid
Vestix	Bioinsecticide	Beauveria bassiana	White fly
Bio-imune	Biofungicide	Bacillus subtilis	Anthracnose
Bio-imune	Biofungicide	Bacillus subtilis	Rust
Camperico	Bioherbicide	Xanthomonas campestris	Poa annua
Lubao	Bioherbicide	Colletotrichum gloeosporioides	Echinochloa crus-galli
Stumpout	Bioherbicide	Cylindrobasidium laeve	Poa annua
Phoma	Bioherbicide	Phoma macrostoma	Taraxacum officinale
Sarritor	Bioherbicide	Sclerotinia minor	Araxacum officeinale
NatureCur	Bioherbicide	Juglans nigra	Portulaca oleraceae Echinochloa crus-galli Portulaca oleraceae Conyza bonariensis Ipomoea purpurea
Bioweed	Bioherbicide	Pine oil	Nassella trichotoma
Avenger Organic	Bioherbicide	d-Limonene and castor oil	Grass and broadleaf weeds
Bialaphos	Bioherbicide	Streptomyces hygroscopicus	Broad-spectrum
GreenMatch	Bioherbicide	Lemon grass oil	Broadleaf and grassy weeds
Lockdown/Collego	Bioherbicide	Flumioxazin and Colletotrichum gloeosporioides	Residual control of various broadleaf weeds
Opportune	Bioherbicide	Streptomyces strain RL-110 T	Broadleaf and sedges
Weed Slayer	Bioherbicide	Eugenol, clove oil, molasses	Grassy weeds
Stump out	Bioherbicide	Sodium bicarbonate and Cylindrobasidium leave	Poa species

* Source of data: Brazilian App Bioinputs (https://play.google.com/store/apps/details?id=br.embrapa.bioinsumos (accessed on 11 June 2025)) and Roberts et al. [17].

shows some of these products currently available for use.

Bioherbicides

Bioherbicides can present a solution to the issue of weeds resistant to herbicides, but they can degrade easily and need repeated application. Encapsulation technologies can be a good strategy to formulate bioherbicides to have long-term action on the weeds. When compared to other bioinputs, such as biofungicides and bioinsecticides, the number of registered bioherbicides worldwide is low, accounting for less than 10% of registered bioinputs available on the market for commercialization [35]. This scenario exists because weeds pose the highest control challenge from all pests affecting crops, making the development of this type of product laborious.

Considering the production and commercialization of bioherbicides, Brazil currently lacks any registered bioherbicides. However, due to its extensive biodiversity, Brazil holds significant potential for this, and studies indicate that bioherbicides will soon be available in the market. For example, Phoma dimorpha has been effective against Senna obtusifolia [18]. Alternaria alternata metabolites can be efficient in reducing seed germination [36]. Essential oil from Aniba canelilla is a natural resource from the Amazon region and has demonstrated herbicidal effects due to the presence of 1-nitro-2-phenylethane in the plant [37]. Extracts from the leaves of Quillaja lancifolia showed bioherbicidal potential against the weed Echinochloa crus-galli [38]. Aqueous extract of Baccharis trimera presented significant inhibitory potential on the weeds Cyperus ferax and Oryza sativa L. (red rice) in the pre-germination and post-germination phases. Extracts obtained by pressurized liquid extraction at the initial extraction times (1 to 10 min) were the most efficient in inhibiting germination [4]. Among the countries with registered bioherbicides, Canada and the United States are highlighted [35]. The majority of registered bioherbicides in these countries are based on fungi and bacteria. Products based on plant extracts are uncommon and need further exploration.

5. Obtaining Plant Extracts

5.1. Main Plants

Bioherbicides can be produced from plant extracts or essential oils because some plants contain secondary metabolites that can negatively affect the germination and growth of other plants. Additionally, certain plant species can cause abnormalities in weeds, disrupt photosynthesis, and affect the mitotic index, leading to reduced growth of aerial parts and the root system [39]. Bioactive compounds from Ricinus communis and Baccharis trimera, like gallic acid, caffeic acid, ferulic acid, rutin, quercitrin, and kaempferol, have been shown to contribute to allelopathic effects in certain plant species such as red rice (Oryza sativa L.) and Cyperus ferax [4,40]. Various parts of plants, including leaves, fruits, roots, stems, and flowers, can contain these compounds and be used to prepare extracts with bioherbicidal potential.

The most studied plants regarding their herbicidal potential belong to the Lamiaceae family (47%), followed by the Asteraceae family (8%). Among the species of the Lamiaceae family that exhibit this potential are rosemary (Rosmarinus officinalis L.), boldo (Coleus barbatus), oregano (Origanum vulgare L.), basil (Ocimum basilicum L.), lavender (Lavandula spp.), peppermint (Mentha spicata L. subsp. Spicata), common sage (Salvia officinalis L.), mint (Mentha spp.), common calamint (Satureja calamintha), thyme (Thymus capitatus L.), marjoram (Origanum majorana), and true lavender (Lavandula angustifolia) [2,39,41]. A summary of plants that exhibit metabolites with bioherbicidal potential is presented in

Table 3. Plants with bioherbicidal potential against weeds in corn and bean crops.

Plant	Botanical Part	Weed	Effects	Ref.
Eucalyptus camaldulensis	Leaves	Bidens pilosa	Germination inhibition	[42]
Dipteryx lacunifera Ducke, Ricinus communis L., Piper tuberculatum, and Jatropha gossypiifolia L.	Leaves	Bidens bipinnata L.	Germination inhibition and reduction in seedling growth	[11]
Eucalyptus citriodora, Lavandula angustifolia, and Pinus sylvestris	Leaves	Portulaca oleracea flowers and needles	Germination inhibition and reduction in seedling growth	[43]
Eucalyptus citriodora and Cymbopogon nardus	-	Digitaria horizontalis and Cenchrus echinatus	Reduction in dry mass accumulation and reduction in chlorophyll content	[13]
Artemisia vulgaris L.	-	Amaranthus retroflexus	Inhibition of seed germination, seedling emergence, and plant growth of redroot pigweed	[14]
Cuscuta campestris	Stalk	Amaranthus retroflexus	Germination inhibition and reduction in seedling growth	[44]
Eucalyptus camaldulensis	-	Digitaria insularis	Germination inhibition	[42]
Calliandra haematocephala	Leaves and inflorescences	Echinochloa crus-galli	Germination inhibition	[45]
Eucalyptus grandis	Leaves	Cyperus rotundus	Germination inhibition	[12]
Carlina acaulis	Roots	Bidens pilosa L.	Leaf necrosis and interference with photosynthesis	[15]
Ocimum basilicum L.	Leaves and flowers	Amaranthus spp. and Portulaca oleraceae	Germination and growth inhibition, and a reduction in dry weight and length of roots	[46]
Sinapis alba L.	Seeds	Amaranthus powellii and Setaria viridis	Germination inhibition, necroses, and reduction in plant height	[47]
Cynara cardunculus L. var. altilis DC	Leaves	Amaranthus retroflexus L., Portulaca oleracea L., and Stellaria media	Inhibition of germination	[48]
Cymbopogon citratus	Leaves	Echinochloa crus-galli	Inhibition of seed germination and seedling growth, reduction in chlorophyll, interference with seed amylase activity, and leaf wilting	[23]

.

Eucalyptus is one of the most studied plants for the bioherbicidal potential against weeds commonly found in bean and corn crops. Eucalyptus species such as Eucalyptus citriodora, Eucalyptus grandis, Eucalyptus globulus, and Eucalyptus camaldulensis have been studied for their phytotoxic effects on weed species. This outcome is attributed to the compounds present in the species, such as α-pinene, 1,8-cineole, and citronellol [2,41], which not only possess bioherbicidal potential but also bioinsecticidal effects on various species.

5.2. Main Methods for Obtaining Plant Extracts

Some steps are necessary to achieve the final preparation of extracts (Figure 5). The first step involves collecting the desired material, avoiding parts affected by insects or diseases. The season can influence the production and accumulation of secondary metabolites responsible for causing allelopathy in weeds. After collection, the plant material preparation includes cleaning to remove undesired materials such as soil and sand and selecting the material by eliminating undesired parts of the plant.

Subsequently, the plant material is dried, usually in a greenhouse. Care must be taken with high temperatures to prevent compound degradation. Therefore, the drying temperature should not exceed 50 °C for leaves, while it can be slightly above 50 °C for thicker materials. If the goal is to use fresh material, this step is skipped, and the process moves on to the next stage. Before extraction, the plant material is ground to reduce particle size, which can be performed using various types of mills or simpler tools such as scissors and blenders. Once ground, the material is ready for extraction, which can be performed using several methods. For extracting plant compounds, techniques range from simple to complex, involving several variables. Common methods include infusion [3,49], maceration [50], Soxhlet [51], percolation [49,52], hydrodistillation [43], digestion, and decoction [49]. More advanced and novel techniques include Pressurized Liquid Extraction (PLE) [4], Ultrasound-Assisted Extraction (UAE) [3], Supercritical Fluid Extraction (SFE) [53], Microwave-Assisted Extraction (MAE) [54], Turbolysis [55], and Microwave Hydrodiffusion and Gravity (MHG) [56].

• Infusion: This is one of the simplest methods used, similar to making tea. It involves placing the heated solvent, usually distilled water, but other solvents such as ethanol can also be used, in contact with the plant material for several minutes to allow infusion. The advantage lies in rapid extraction. In the environmental aspect, the use of GRAS (Generally Recognized As Safe) solvents is a benefit. The main variables are temperature and extraction time. The infusion method is used to obtain volatile and water-soluble compounds.
• Maceration: The plant material, usually fresh or dried, is crushed or ground with a solvent, usually ethanol or hydroethanolic mixtures, and left for a long time. In the environmental aspect, the use of GRAS solvents is an advantage. A long extraction time is a disadvantage. The main variables are temperature and extraction time. Maceration is recommended for extracting plant materials rich in extracts of interest and without a defined cellular structure, including thermolabile compounds.
• Soxhlet: It is a continuous method, where plant material is placed on a filter paper and inserted into the apparatus. Then, a distillation flask is filled with solvent. A siphon aspirates the solvent, such as n-hexane, from the filter paper and returns it to the distillation flask, transporting and extracting the substances of interest. This process is repeated until complete extraction is achieved. It is used in the extraction of non-volatile compounds. It needs a long extraction time and often relies on hazardous organic solvents like n-hexane. The advantage of Soxhlet lies in enabling efficient solvent recycling within the system, thereby reducing overall solvent waste compared to open percolation setups, though its total solvent volume may still be significant. The variables involved in this process are the biomass-to-solvent ratio and extraction time.
• Percolation: This is a continuous method where the solvent at room temperature (approximately 25 °C) passes through the dried and ground plant material. The method is used for extracting compounds soluble in liquid solvents. The main advantage is a rapid extraction time, while the high solvent consumption is a disadvantage. The efficiency depends on factors such as the particle size of the plant material, the shape and dimensions of the percolator, and the solvent flow rate. The absence of heating represents a positive environmental aspect, as it eliminates the need for fossil fuel consumption.
• Hydrodistillation: This method is used for extracting essential oils. It involves the contact of plant material with water, which, upon boiling, carries volatile compounds. Upon condensation, a heterogeneous mixture is formed, consisting of the essential oil and hydrosol (a by-product of the essential oil). The separation of these compounds is performed to obtain the essential oil. The Clevenger-type distillation apparatus is commonly used for this type of extraction. The main variable is the extraction time. The use of water is a benefit in the environmental aspect.
• PLE: This method involves subjecting the solvent to moderate temperatures (50–90 °C) and moderate to high pressures (2–20 MPa) to extract desired metabolites from the plant material. The method is considered a green technology as it uses water or organic solvents such as ethanol. The main variables are temperature, pressure, solvent/biomass ratio (g/g), and extraction time. This type of method is not recommended for extracting heat-sensitive compounds, as they may be degraded due to the temperature used in the process.
• UAE: This method involves the propagation of low-frequency mechanical waves where the plant material, mixed with the solvent, comes into contact with an ultrasonic probe. This probe ruptures the plant cell wall, enhancing contact with the solvent and facilitating the extraction of desired compounds. It is suitable for extracting heat-sensitive compounds. Low solvent consumption and extraction time are advantages, aligning with the principles of green chemistry and sustainable processing. The main variables include power (Watts) or energy density (Joules per cubic centimeter), pulse cycle (dimensionless), extraction time (minutes), and, in some cases, frequency (Hertz).
• SFE: In this method, the solvent is raised to temperatures and pressures above its critical point, which can be either liquids or gases. CO₂ is the most commonly used solvent in this type of extraction because it is low-cost, non-toxic, and non-flammable. It is used in the extraction of polar or slightly polar compounds. SFE with supercritical CO₂ is widely considered a green and safe method due to the non-toxic and non-flammable nature of the solvent. The main variables are temperature, pressure, solvent/biomass ratio (g/g), addition of polarity modifiers, and extraction time.
• MAE: The extraction occurs through uniform microwave heating. Extraction is carried out quickly and effectively due to the high pressure and temperature of the system. Compounds that are soluble in polar and non-polar solvents used in extraction can be recovered by this method. It offers advantages such as short extraction time and the possibility of extracting multiple samples simultaneously. The main variables are microwave power, irradiation time, extraction time, frequency, and solvent/biomass ratio (g/g).
• Turbolysis: The method involves extraction with agitation, reducing the size of the particles of the plant material used due to the high shear force applied in the process, leading to the rapid dissolution of the substances of interest. The method is indicated for obtaining water-soluble compounds. It offers advantages such as speed, efficiency, and simplicity of extraction, while its disadvantages include heat generation, filtration difficulties, and limitations in using materials of high hardness. The main variables are extraction time, temperature, and speed.
• MHG: This method is based on the combination of microwaves with hydrodiffusion, typically used for the extraction of essential oils and phenolic compounds. In the environmental aspect, the process occurs at atmospheric pressure and does not require the use of solvents. It offers advantages such as rapid extraction, making it a clean technology, and providing a high extraction yield. The main variables are power, frequency, and extraction time.

6. Bioactive Compounds Against Weeds in Organic Bean and Corn Farming

Some plants produce compounds called allelopathic substances, which are released into the environment. These compounds can interfere with the germination and growth of other plant species, such as weeds. In some instances, they are selectively harmful, impacting only weeds without damaging crops. Compounds such as steroids, tannins, ketones, aldehydes, quinones, phenolics, flavonoids, terpenoids, and lactones have this potential against weeds. Plants containing these compounds can be used to extract compounds for producing bioherbicides [39].

Several plants have been studied for their potential for allelopathy against weeds. Calliandra haematocephala Hassk has shown allelopathy against weeds such as Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona L., Eclipta prostrata L., and Rottboellia cochinchinensis (Lou.) W.D. Clayton. Allelopathy is caused by compounds such as alkaloids, steroids, flavonoids, sesquiterpenes, terpenes, saponins, lactones, and coumarins, which have been identified in the extracts of the inflorescences and leaves of the species [45].

The essential oil of Carlina acaulis has exhibited allelopathy against the weed Bidens pilosa L. The allelopathy was caused by compounds such as isohexenic acid, fumaric acid, allose, D-(−)-ribose, quinic acid, shikimic acid, tagatose, D-(+)-mannose, D-(−)-fructose, and glucose [15]. Species of Eucalyptus are also studied for their bioherbicidal potential, which is attributed to the presence of phenolic and volatile compounds. In Eucalyptus spp., compounds such as 1,8-cineole, limonene, α- and β-pinene have been identified [57].

Essential oils from Eucalyptus citriodora, Lavandula angustifolia, and Pinus sylvestris were tested for their bioherbicidal potential against the weeds Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli. Compounds such as linalool and 1,8-cineole were identified in Lavandula angustifolia, citronellal in Eucalyptus citriodora, and α-pinene in Pinus sylvestris, which are responsible for affecting the germination and growth of weeds [43]. Therefore, these outcomes suggest that essential oils rich in bioactive compounds hold promising potential as natural tools for weed management in bean and corn farming.

The compounds with bioherbicidal potential found in plants can affect weeds in different ways, which are referred to as mechanisms of action. These mechanisms can be classified as direct, when they directly affect the target, or indirect, when they are released into the soil and, through the degradation of compounds, hinder development or alter the microenvironment of the target, affecting its growth [35]. Thus, understanding the direct and indirect mechanisms of action of plant-derived compounds is necessary to optimize their application as sustainable bioherbicides.

The various mechanisms of action include interference with the activities of certain enzymes and endogenous hormonal synthesis, interference with plant respiration, interference with the plant–water relationship, interference with the integrity and permeability of the cell membrane, inhibition of protein synthesis and nucleic acid metabolism, interference with cellular morphology and multiplication, interference with soil microbial activity, and inhibition of protein synthesis and nucleic acid metabolism [7]. The effect of certain plant extracts on weeds has been investigated (

Table 4. Some compounds found in different plants and their mechanisms of action.

Compound	Plants	Mechanisms of Action	Ref.
Carvacrol	Thymus algeriensis and Origanum vulgare	They disrupt the cell membrane and influence metabolic pathways, photosynthesis, cellular respiration, and mitosis	[41]
α-Terpinene	Origanum onites and Origanum vulgare
Thymol	Thymus algeriensis
Eugenol	Syzygium aromaticum and Eugenia caryophyllus	It causes damage to cell membranes and inhibits photosynthesis
Geranial	Ocimum basilicum	It interferes with germination and growth
Monoterpenes and sesquiterpenes	Artemisia scoparia Waldst et Kit	They inhibit growth, cellular respiration, and the occurrence of chlorosis and necrosis	[39]
Rocaglaol	Aglaia odorata Lour.	It inhibits the growth of weeds
Drimane sesquiterpenes	Drimys brasiliensis Miers	They inhibit seed germination, seedling growth, and cell division of the metaxylem in roots
α-Pinene and 1,8-cineole	Eucalyptus tereticornis	They inhibit the growth and vigor of seedlings, respiration, and pigment synthesis
Carvone	Genera of the Lamiaceae family	It inhibits germination, and radicle and pedicle lengths	[58]
Flavonoids and terpenoids	Artemisia vulgaris L.	They inhibit seed germination, seedling emergence, and plant growth of redroot pigweed	[14]

).

7. Plant Extracts for Weed Control in Organic Bean and Corn Farming

Currently, research on discovering plants with bioherbicide potential is increasing due to the wide variety of plant species containing phytochemicals that can be used for this purpose and the global need for sustainable agriculture. There is also growing interest in natural products for weed control that are environmentally friendly. These phytochemicals found in plants, such as phenolics, ketones, aldehydes, quinones, and terpenoids, interfere with the germination and development of weeds. Some of these phytochemicals can target weeds specifically without harming the crop. They act by inhibiting seed germination and plant growth, as well as by disrupting photosynthesis, cellular respiration, and mitosis. Phenolic compounds may reduce weed seed germination by decreasing amylase activity. Fatty acids can cause disorganization of cell membranes, leading to a loss of cellular function. Phytochemicals in plants can also alter weed protein metabolism through abnormal regulation, which can suppress chlorophyll synthesis and negatively impact photosynthesis [39].

Phenolic compounds and terpenoids are the most commonly reported compounds for their bioherbicidal activity. Terpenoid compounds include monoterpenes, diterpenes, and sesquiterpenes. Monoterpenes are the most frequently reported for their bioherbicidal activity, being widely found in essential oils, where they inhibit weed germination and growth [2]. Examples of monoterpenes include citronellal, citronellol, carvacrol, γ-terpinene, and thymol. Citronellal causes a phytotoxic effect on seed germination and weed development, citronellol induces oxidative stress in weeds, and carvacrol, γ-terpinene, and thymol can break cell membranes and interfere with photosynthesis, cellular respiration, and mitosis [40]. Phenolic compounds include flavonoids and tannins, which are generally components found in aqueous plant extracts. Eugenol is an example of a phenolic compound that causes damage to the cell membrane and prevents photosynthesis in plants [2].

In this regard, a search was conducted on the Science Direct platform from 2013 to 2023 using the keywords “plant extracts”, “bioherbicide”, and “weeds” to find articles related to using plant extracts for weed control and to track the number of these studies over time. An increase in research on plant extracts with bioherbicidal potential is evident. After filtering out studies involving microorganisms, book chapters, and review articles, 242 articles were included. Comparing the number of articles found on Science Direct in 2013 and 2023, only 5 articles were identified in 2013, whereas in 2023, this number rose to 30. The list of the most-cited articles is presented in

Table 5. Compilation of data about plant extracts for weed control on the Science Direct platform from 2013 to 2025; articles with more than 10 citations were selected for those published from 2013 to 2020; articles with more than 10 citations were chosen for those published from 2021 to 2023; all articles were selected from 2024 to 2025 (search conducted in June 2025).

Citations	Year	Title	Affiliation Country	Plant	Weed	Main Findings	Ref.
87	2014	Chemical composition, antimicrobial, insecticidal, phytotoxic, and antioxidant activities of Mediterranean Pinus brutia and Pinus pinea resin essential oils	Turkey	Pinus pinea and Pinus brutia	Portulaca oleracea L.	The highest dose of the essential oils of P. brutia and P. pinea caused inhibitory effects on the germination of P. oleracea by 13% and 3%, respectively	[59]
79	2013	Secondary metabolites from Chrysanthemum coronarium (Garland) flowerheads: Chemical composition and biological activities	Tunisia and France	Chrysanthemum coronarium	Sinapis arvensise Phalaris canariensis	The essential oil showed good antimicrobial activity against B. aereus and S. aureus; the extract exhibited phytotoxic effects	[60]
69	2020	Formulation and assessment of nano-encapsulated bioherbicides based on biopolymers and essential oil	Iran	Satureja hortensis L.	Amaranthus retroflexus L.	The encapsulation of essential oil with biopolymers and natural crosslinkers was effective and increased its herbicidal activity compared to the non-nanometric essential oil emulsion without polymer	[61]
65	2020	Screening of Tunisian plant extracts for herbicidal activity and formulation of a bioherbicide based on Cynara cardunculus	Tunisia	L. guyonianum, P. harmala, R. chalepensis, R. communis, N. retusa, C. cardunculus, A. herba-alba, M. edule, T. gallica, and D. stramonium	Trifolium incarnatum, Silybum marianum, and Phalaris minor	C. cardunculus was the only plant that showed bioherbicidal potential in both pre- and post-emergence weed control	[62]
57	2020	Leaf extracts of cultivated cardoon as potential bioherbicide	Italy	Cynara cardunculus L. var. altilis DC.	Amaranthus retroflexus L., Portulaca oleracea L., Stellaria media (L.) Vill., and Anagallis arvensis L.	Significant allelopathic effect on the germination of weed seeds, with extracts from dried leaves and ethanol being the most effective	[48]
55	2021	Chemical composition and phytotoxicity of essential oil from invasive plant Ambrosia artemisiifolia L.	China	Ambrosia artemisiifolia	Poa annua, Setaria viridis, Amaranthus retroflexus, and Medicago sativa	The essential oil of A. artemisiifolia inhibited seed germination and seedling development in the weeds, even at low concentrations	[63]
47	2021	Nanoemulsion of Foeniculum vulgare essential oil: A propitious striver against weeds of Triticum aestivum	India	Foeniculum vulgare Mill	Phalaris minor Retz., Avena ludoviciana Durieu, Rumex dentatus L., and Medicago denticulata	F. vulgare showed bioherbicidal potential, being effective even at low doses	[64]
43	2020	Essential oil of Bassia muricata: Chemical characterization, antioxidant activity, and allelopathic effect on the weed Chenopodium murale	Egypt and Saudi Arabia	Bassia muricata	Chenopodium murale	The essential oil of B. muricata significantly reduced the germination and seedling development of the weed Chenopodium murale	[65]
41	2018	Management of the noxious weed; Medicago polymorpha L. via allelopathy of some medicinal plants from Taif region, Saudi Arabia	Saudi Arabia	Achillea santolina L., Pituranthus tortuosus L., and Thymus capitatus L.	Medicago polymorpha L.	The allelopathic potential of the species on Medicago polymorpha L. was confirmed; the species with the highest allelopathic potential were A. monosperma, T. capitatus, and A. santolina	[66]
39	2020	Chemical composition variations, allelopathic, and antioxidant activities of Symphyotrichum squamatum (Spreng.) Nesom essential oils growing in heterogeneous habitats	Egypt	Symphyotrichum squamatum	Bidens pilosa	Significant allelopathic activity against the root and shoot growth of Bidens pilosa; the inhibition was dose-dependent, with the root system of B. pilosa being more inhibited than the shoot system	[67]
38	2017	Phytotoxic effects of essential oils in controlling weed species Digitaria horizontalis and Cenchrus echinatus	Brazil	Eucalyptus citriodora and Cympobogon nardus	Digitaria horizontalis and Cenchrus echinatus	Strong phytotoxic effects on seed germination, plant development, and reduction in chlorophyll and protein content	[13]
37	2018	Bioherbicidal activity of Sinapis alba seed meal extracts	USA	Sinapis alba	Amaranthus powellii and Setaria viridis	The powder from extracts of S. alba containing SCN- as the active ingredient can be reconstituted in water and applied as a spray in the form of a bioherbicide in pre- and post-emergence	[47]
37	2020	Allelopathic potential and phenolic allelochemicals discrepancies in Ficus carica L. cultivars	Tunisia	Ficus carica L. cultivars	Peganum harmala L. and Silybum marianum L.	Leaf extracts were more toxic and significantly influenced seedling elongation compared to branch extracts	[68]
36	2018	Origanum vulgare essential oils inhibit glutamate and aspartate metabolism altering the photorespiratory pathway in Arabidopsis thaliana seedlings	Italy	Origunum vulgare	Arabidopsis thaliana	Interference in glutamine metabolism, excessive accumulation of toxic inorganic nitrogen in the leaves associated with oxidative stress and damage, and decreased efficiency of the photosynthetic apparatus associated with reduced CO2 fixation	[69]
32	2017	Phytotoxic activities of essential oils and hydrosols of Haplophyllum tuberculatum	Tunisia, Belgium, and Italy	Haplophyllum tuberculatum	Raphanus sativus L.	Essential oils from H. tuberculatum have a significant phytotoxic effect on the species	[70]
28	2019	Herbicidal activities of compounds isolated from the medicinal plant Piper sarmentosum	China	Piper sarmentosum	Echinochloa crus-galli, Digitaria sanguinalis, Poa annua L., Eleusine indica (L.), Echinochloa phyllopogon, and Chloris virgata	Sarmentosin could effectively control E. crusgalli, Chloris virgata, Pharbitis nil, A. retroflexus, and Abutilon theophrasti	[71]
27	2020	Interspecific variations in the habitats of Reichardia tingitana (L.) Roth leading to changes in its bioactive constituents and allelopathic activity	Egypt and Saudi Arabia	Reichardia tingitana Roth	Amaranthus lividius and Chenopodium murale	The methanolic extract of R. tingitana exhibited significant allelopathic activity against Chenopodium and Amaranthus, where germination was completely inhibited at concentrations of 75 mg L−1 and 50 mg L−1	[72]
27	2018	Characterization of phytochemical profile and phytotoxic activity of Mimosa pigra L.	Thailand	Mimosa pigra L.	Ruellia tuberosa L.	Root growth of the plants was inhibited in a concentration-independent manner, significantly inhibiting mitosis	[73]
25	2015	Bioherbicidal activity of drimane sesquiterpenes from Drimys brasiliensis Miers roots	Brazil	Drimys brasiliensis Miers	Barbarea verna (Mill.), Echinochloa crus-galli (L.), and Ipomoea grandifolia	The sesquiterpenes identified as polygodial, polygodial acetal, dendocarbina L., and (+)-fuegin presented the highest levels of activity at low concentrations on all target species	[74]
25	2017	Phytoinhibitory activities and extraction optimization of potent invasive plants as eco-friendly weed suppressant against Echinochloa colona (L.)	Malaysia	Ageratum conyzoides (L.), Asystasia gangetica (L.), Clidemia hirta (L.), Dicranopteris linearis, Imperata cylindrica (L.) Melastoma malabathricum (L.), Mikania micrantha, Ottochloa nodosa, and Pennisetum polystachion	Echinochloa colona (L.)	Leaf extracts of M. micrantha, C. hirta, D. lienaris, and A. conyzoides promoted the highest inhibitory activities	[75]
24	2020	Water-soluble phenolic acids and flavonoids involved in the bioherbicidal potential of Ulex europaeus and Cytisus scoparius	Spain	Ulex europaeus and Cytisus scoparius	Amaranthus retroflexus and Digitaria sanguinalis	Eleven and seventeen phenolic compounds were identified in the aqueous extracts of U. europaeus and C. scoparius, respectively	[76]
22	2022	Potential of solid wastes from the walnut industry: Extraction conditions to evaluate the antioxidant and bioherbicidal activities	Chile	Juglans regia	Broadleaf and narrowleaf weeds	High presence of phenolic compounds with antioxidant activity, which can be effectively recovered using ethanol	[77]
21	2022	Allelopathic effects of Juniper essential oils on seed germination and seedling growth of some weed seeds	Bulgaria	Juniperus sabina L. and J. excelsa Bieb.	Melilotus officinalis L., Trigonella besseriana Ser., and Myosotis arvensis (L.) Hill.	The essential oils exhibited inhibitory effects on weed seeds	[78]
20	2013	Suppression effects of Lantana camara L. aqueous extracts on germination efficiency of Phalaris minor Retz. and Sorghum bicolor L. (Moench)	Egypt	Lantana camara L.	Phalaris minor Retz.	The inhibitory effect on the percentage of germination and germination index of seeds from the weed species was proportional to the concentration of the extract	[79]
16	2020	Effect of olive vegetation water and compost extracts on seed germination of four weed species	USA	Olea europaea L.	Amaranthus retroflexus L., Malva parviflora L., Portulaca oleracea L., and Sonchus oleraceus L.	Complete inhibition or delay in the germination of weed seeds during the first week after application	[80]
15	2019	Analysis of Melaleuca cajuputi extract as the potential herbicides for paddy weeds	Malaysia	Melaleuca cajuputi	Echinochloa crus-galli	The extract of Melaleuca cajuputi at a concentration of 0.05 M exhibited necrosis and chlorosis	[81]
12	2023	Effects of organic and inorganic mulching, nettle extract, and manual weeding on weed management under direct-seeded lentil in Meknes region, Morocco	Marocco	Urtica dioica L.	Weed plants of lentil	Germination inhibition of more than 50% of Glebionis coronaria (L.) seeds and more than 80% of Avena stirilis (L.)	[82]
12	2021	Predictive phytotoxic value of water-soluble a lelochemicals in plant extracts for choosing a cover crop or mulch for specific weed control	Spain	Bromus species mixture; Festuca arundinacea Schreb., Hordeum murinum L., H. vulgare L., Vulpia ciliata Dumort., Medicago rugosa Desr., M. sativa L., Trifolium subterraneum L., T. incarnatum L., Phacelia tanacetifolia Benth., Sinapis alba L., and Pinus sylvestris L.	Conyza bonariensis (L.) Cronquist, Aster squamatus (Spreng.) Hieron, and Bassia scoparia (L. A. J.)	Germination of A. squamatus and C. bonariensis was reduced by 80–100% by the extracts applied at 50% concentration and completely blocked at 100% concentration; C. bonariensis root growth showed only some tolerance to the crude extracts of F. arundinacea and P. sylvestris; Bassia scoparia was relatively tolerant to the aqueous plant extracts, except for T. subterraneum crude extract, which reduced total germination by 80%; B. scoparia showed higher general sensitivity of shoot growth than the other two weed species	[83]
9	2023	Complementing cultural weed control with plant allelopathy: Implications for improved weed management in wheat crop	Pakistan	Parthenium hysterophorus L., Sorghum halepense (L.) Pers., Helianthus annuus L., Triticum aestivum L., and Eucalyptus globulus	Phalaris minor Retz., Avena fatua L.; Poa annua L.; Fumaria indica L., Euphorbia helioscopia, and Chenopodium album L.	Weed density reduction, increasing wheat quality and production	[84]
9	2022	Terpenes and phenolics in alcoholic extracts of pine needles exhibit biocontrol of weeds (Melilotus albus and Asphodelus tenuifolius) and insect-pest (Plutella xylostella)	Pakistan	Pinus roxburghii	Melilotus albus and Asphodelus tenuifolius	Inhibition of the germination of weeds	[85]
0	2025	Unveiling the allelopathic potential of common weeds extracts for effective management of Parthenium hysterophorus	Pakistan	Parthenium hysterophorus	S. viridis, Chenopodium album, C. rotundus, E. helioscopia, R. dentatus, C. tinctorius, X. strumarium, E. bonariensis, P. australis, and I. cylindrica	The extracts inhibited the germination, shoot and root lengths, biomass, and pigment contents of weeds; E. bonariensis and I. cylindrica effectively suppressed shoot and root growth; C. album demonstrated the most potent impact on dry biomass, leaf chlorophyll, and leaf carotenoid content	[86]
0	2025	Assessment of the bioherbicidal potential of Thymus sp. pl. essential oils in weed control	Italy and Algeria	Thymus algeriensis Boiss. et Reut. and Thymus ciliatus Desf.	Lolium perenne L. and Amaranthus retroflexus L.	All essential oils were effective against weeds in the pre-emergence stage; Lolium perenne L. showed resistance to the essential oils, while A. retroflexus was highly sensitive	[87]

.

Based on the compiled data from Table 4 and Table 5, natural compounds and botanical extracts show varying but significant levels of effectiveness in weed control. Compounds like carvacrol, eugenol, and sesquiterpenes effectively inhibit key physiological processes, including germination, cellular respiration, and cell division, reinforcing their bioherbicidal potential. Similarly, the studies report that essential oils and extracts from species such as Ambrosia artemisiifolia, Cynara cardunculus, and Foeniculum vulgare produce notable inhibitory effects on seed germination and seedling growth, even at low concentrations or when enhanced through nanotechnological formulations. Some studies indicate partial or dose-dependent effects, as seen with Pinus pinea and Pinus brutia, where germination inhibition was limited. Overall, the evidence suggests that although activity levels may vary, plant-derived secondary metabolites are promising alternatives to synthetic herbicides, especially when supported by formulation strategies that improve their stability and effectiveness.

Formulation

Compounds with herbicidal properties face significant hurdles in practical use because they are often degraded quickly in the environment. This fast degradation limits how long they stay active in the field and reduces their effectiveness [88]. To deal with these issues, researchers are looking for nano- and micro-encapsulation technologies. These advanced methods aim to boost the stability of herbicidal compounds and allow for their controlled release, theoretically extending their weed-fighting power. However, while promising, these encapsulation techniques add complexity and cost to the manufacturing process [89,90,91,92,93].

These encapsulation technologies combine herbicidal compounds with various formulation agents to enhance the stability, effectiveness, and delivery. These agents are categorized into three main groups. Active ingredients directly target weeds, disrupting their growth or metabolic processes. Formulation agents increase performance and stability, including water as a diluent, oils for adhesion and spreading, surfactants to reduce surface tension and improve coverage, and additives like preservatives or stabilizers to extend shelf life. This blend ensures the bioherbicide performs optimally in diverse conditions [34,94].

Beyond the main active ingredients and formulation agents, adjuvants are essential for enhancing application and effectiveness. These additional substances, although they do not directly target weeds, greatly enhance the product’s performance. Important adjuvants include spreader-stickers to promote distribution and adhesion, penetrants to boost absorption into weed tissues, and pH adjusters to improve effectiveness and compatibility. Including adjuvants strategically ensures that the bioherbicide reaches its target efficiently and is absorbed properly [22,95,96].

Throughout the manufacturing process, strict quality control measures are applied to ensure the bioherbicide meets specific standards for effectiveness, safety, and consistency. This includes thorough testing for potency, stability, and purity before the product is packaged and shipped with clear labeling and instructions. The main goal of bioherbicide production is to create environmentally safe and effective weed control solutions that cause minimal harm to non-target plants. As research progresses, bioherbicides present a promising path toward more sustainable and eco-friendly weed management strategies in various settings [34].

8. Patents

With the discovery of plants showing bioherbicidal potential, the success of these species is being validated. The bioherbicidal ability of plants has been demonstrated to be effective in both pre- and post-emergence stages of weeds, causing various harmful effects on plant growth. For example, it reduces germination, germination speed index, and root and shoot lengths, causes visible damage to plants, and changes photosynthesis, among other effects. As a result, there has been increased exploration of patent filings on this topic. The search for existing registered patents was conducted using platforms like INPI, Espacenet, and WIPO with keywords such as “plant extracts,” “bioherbicide,” “weeds,” “organic bean,” “organic corn,” and “organic farm.” The patents are listed in

Table 6. Selected patents for bioherbicides based on extracts.

Title	Year	Country	Summary of the Invention	Ref.
Bioherbicide from Festuca spp.	2013	United States	Identification of plants with herbicidal potential and methods of using m-tyrosine compounds from Festuca spp. for weed control	[97]
Use of an aqueous solution, suspension or mixture of the same, obtained from air parts and/or parts below the Tulbaghia violacea soil and Agapanthus africanus soil to inhibit fungal infection of a harvest change	2013	Brazil	Product based on plant extracts from Agapanthus for use in plant protection	[98]
A natural herbicide containing lemongrass essential oil	2013	United States	The use of compounds in lemongrass oil for controlling broadleaf weeds and grasses	[99]
Allelopathic activity of components and products from the seeds of Euterpe edulis Martius, Arecaceae	2014	Brazil	Identification of the allelopathic properties of seeds from the species Euterpe edulis in environmental and agricultural contexts	[100]
Natural bioherbicides and related materials and methods	2014	United States	Weed control through bioherbicidal compositions based on plant extracts (Russian olive, Austrian pine, tree of heaven, autumn olive, and black walnut extract)	[101]
Natural herbicide containing wood tar oil and production method thereof	2017	China	Production of a natural herbicide containing wood tar oil for weed control	[102]
Use of essential oil from Aloysia triphylla and the process of controlling dicotyledonous plants and/or seeds	2018	Brazil	Bioherbicide developed from the essential oil of Aloysia triphylla for controlling dicotyledonous weeds	[103]
Process of obtaining a natural herbicide for spraying without harmful effects on human, animal, and plant health	2019	Brazil	Natural products for weed control developed from the fermentation in vinegar and alcohol of medicinal plants such as banana leaves, jabuticaba leaves, guava leaves, and lemons	[104]
Biological herbicide for extinguishing Ageratina adenophora	2019	China	Bioherbicide for controlling Ageratina adenophora	[105]
Application of Ambrosia artemisiifolia essential oil as herbicide	2019	China	Application of Ambrosia artemisiifolia essential oil as an herbicide in monocotyledon and dicotyledon weeds	[106]
Herbicide comprising plant extracts	2020	Italy	Herbicide based on plant extracts of Sorghum bicolor, Nospospondia, Artemisia absinthium, Prunus laurocerasus, Atropa belladonna, Arabidopsis, Beta vulgaris, and Stachys tuberifera	[107]
Herbicide compositions and methods to control weeds in organic crop production	2021	Chile	Composition, preparation, and utilization of bioherbicide from extracts of plants from the Myrtaceae family for weed control	[108]
Bioherbicide for regweed control and method of application	2022	Serbia	Bioherbicide containing Litsea citrata essential oil as the active ingredient, which can be used for the control of both monocotyledonous and dicotyledonous weeds	[109]
100% non-toxic natural organic natural bioherbicide to combat undesired vegetation on plants	2022	Brazil	Formulation of a 100% non-toxic natural organic composition, prepared from various components formulated in an aqueous solution, with biodegradable characteristics	[110]
Herbicidal Mentha pantsd, extract compositions and methods of using same	2023	United States	Composition of herbicide based on plant extract of Mentha sp.	[111]
Herbicidal, bioherbicidal or herbicide additive compositions, process for producing the compositions, method for controlling weed pests, and use of salicylic acid and plant extract	2023	Brazil	Salicylic acid and/or its derivatives are used, whether or not associated with cinnamon extracts or their active ingredients (cinnamaldehyde or cinnamic aldehyde), for the production of bioherbicides; a process for producing compositions for weed control in crops such as soybeans, corn, beans, and sugarcane	[112]
Composition of contact desiccant bioherbicide	2025	Brazil	The invention refers to an organic composition produced from the development of a syrup based on organic citrus fruits (Citrus × Limonia) and leaves of the Eucalyptus citriodora through fermentation using the cultivation of fungi known as yeasts of the genus Saccharomyces, subsequently added to the combination of organic inputs, for application as a desiccant in soybean cultivation, in direct combat against weeds	[113]

.

9. Summary of Findings, Concluding Remarks, and Future Outlooks

The exploration of the potential of plant extracts as bioherbicides has increased in recent years, encouraged by the search for natural products that can be used without harming the environment. Many studies highlight the potential of plant extracts such as Cuscuta campestris, Cymbopogon citratus, Calliandra haematocephala, Mentha sp., and various species of Eucalyptus to inhibit weeds found in corn and bean crops. In the data compilation carried out on the ScienceDirect platform concerning studies on plant extracts for weed control between 2013 and 2025, it was observed that the plant families most studied for their allelopathic potential were the Asteraceae, Poaceae, Fabaceae, and Lamiaceae families. Most of the articles found on the platform tested the effect of plant extracts from the Asteraceae family, followed by the Poaceae, the Fabaceae, and the Lamiaceae.

Some compounds found in plants responsible for allelopathy in weeds have been identified, such as tannins, ketones, aldehydes, quinones, phenolics, flavonoids, terpenoids, lactones, and steroids. These compounds cause phytotoxicity, interfering with the germination and development of weeds, altering photosynthesis, disrupting cell membranes, causing chlorosis and necrosis, and affecting mitosis, among other effects. Germination inhibition is the most commonly reported response in studies, with examples showing significant weed germination inhibition of 74% when using Pinus roxburghii extracts, 100% when using Eucalyptus grandis oil, and 80.75% when using Cymbopogon citratus oil.

The studies suggest that many plants could potentially be used to produce bioherbicides for controlling common weed species in these crops, offering an alternative option for other organic agricultural practices. However, it is crucial to conduct multiple repeat studies to further evaluate the potential of plant extracts, particularly under field conditions, which represent the real-world scenario, to confirm the product’s effectiveness. Additionally, identifying the compounds responsible for causing allelopathy in weed plants is important. It is expected that plant extract-based bioherbicides will become more prevalent in the market, given ongoing research and advancements, as well as the broad range of species that can be used and show promise for this purpose.

This review aims to generate interest in using plant extracts as active ingredients in bioherbicides, promoting their increasing application in products formulated to control weeds. This approach offers a sustainable alternative that benefits the environment and the population compared to traditional herbicides. Therefore, various strategies for exploring plant extract-based bioherbicides can be implemented, following some steps like those presented in Figure 6. These strategies are outlined for future research focused on producing bioherbicides from plant extracts, supporting and simplifying their development.