Synthetic Fungicides Research Articles

Atividade antifúngica e mecanismo de ação de monoterpenos contra Botrytis cinerea

ABSTRACT Botrytis cinerea is considered one of the most important post-harvest pathogens being the causative agent of gray rot. To reduce the use of synthetic fungicides, it is important to explore alternative products with antifungal properties. Among these alternative products are essential oils, which present monoterpenes as major compounds. The objective of this study was to evaluate the effects of eight monoterpenes (1,8-cineole, carvacrol, citral, citronellal, citronellol, geraniol, linalool, and thymol) on the control of B. cinerea. The mycelial growth of B. cinerea was assessed after treating it with the monoterpenes at a concentration of 1,000 mg/L. Subsequently, the minimal inhibitory concentrations (IC90) of the monoterpenes that showed the greatest antifungal potential were determined. Carvacrol and thymol were tested on B. cinerea cell membrane integrity, intracellular accumulation of reactive oxygen species (ROS), and mitochondrial membrane potential of the conidia. Among the tested monoterpenes carvacrol, citral, citronellal, citronellol, geraniol, and thymol demonstrated complete inhibition of mycelial growth at a concentration of 1,000 mg/L. Carvacrol and thymol exhibited the lowest IC90 values against B. cinerea, with an IC90 of 125 mg/L. Furthermore, carvacrol and thymol induced conidial death in a dose-dependent manner, resulting in the disruption of cell membrane integrity, increased intracellular ROS levels, and decreased mitochondrial membrane potential. These findings highlight the potential of carvacrol and thymol as alternative means of controlling B. cinerea.

Evaluating the efficiency of essential oils as fumigants in controlling Penicillium digitatum in citrus fruits

Citrus fruits are highly valued for their flavor, nutritional content, and versatility, but their perishable nature makes them susceptible to postharvest losses due to fungal infections. Conventional synthetic fungicides, while effective, raise concerns about food safety and environmental impact. Essential oils have emerged as promising alternatives due to their natural antifungal properties. This study investigates the antifungal activity of four plant essential oils as antifungal fumigants against Penicillium digitatum, the primary cause of green mould disease in citrus fruits. In vitro fumigant assays, Satureja montana essential oil exhibits the highest inhibition percentage against P. digitatum. In vivo experiments confirmed the efficacy of S. montana oil in reducing fungal growth on mandarins. Further analysis of different parameters revealed potential alterations in fruit quality attributes based on ripening, acidity, and firmness. Therefore, essential oils could be a potential alternative and eco-friendly approach for postharvest disease management in citrus fruits, contributing to efforts towards food safety, environmental sustainability, and public health.

Coordination of elicitors and ascorbate-glutathione cycle: A vital nexus for mitigating post-harvest injury and losses of cultivated fruits

Fruit losses and waste are predominantly caused by postharvest diseases, with their management traditionally reliant on pesticides. The extensive utilisation of synthetic fungicides can cause harmful impacts on both human health and the environment, necessitating a reduction in their use. Recent advancements have led to the development of novel, benign strategies using natural or biologically derived compounds. These compounds, known as 'elicitors,' have the strength to instigate the plant's defence mechanism, enhancing the fruit’s resilience counter to future stress and reducing postharvest spoilage. In recent years, the impact of the plant defence system concerning elicitor compounds has been measurable through physiological parameters or the enzymatic activity of molecular markers. Antioxidant activity, a crucial parameter to determine fruit quality and tolerance to biotic and abiotic stresses, significantly functions in stress response and maintaining postharvest quality. Elicitors can prompt endurance in fruits instead of diverse environmental stresses by promoting the biosynthesis of antioxidant components and enhancing antioxidant capability through the ascorbate-glutathione (AsA-GSH) cycle. Recent findings have exhibited that applying chemical elicitors can enhance antioxidant activity by augmenting the content of AsA and GSH and by regulating the redox stability, thereby maintaining quality in harvested fruits. This review summarises recent findings demonstrating how elicitor sprays enrich antioxidant activity in harvested fruits by accelerating the synthesis of antioxidants and defence components. This provides insight into fruit defence mechanisms induced under various elicitors and their prospects in postharvest biology.

Effectiveness of GRAS substances for managing leaf diseases in brinjal (<em>Solanum melongena</em> L)

Leaf diseases in brinjal (Solanum melongena L.) are common and drastically lower its yield. As synthetic fungicides are hazardous to the environment and human health, non-fungicidal approaches to foliar disease control are being adopted progressively. The current investigation assessed the effectiveness of Generally Recognized as Safe (GRAS) substances in the management of leaf diseases in brinjal. The efficacy of the selected GRAS substances, including 400 μM of salicylic acid, 0.1% of sodium bicarbonate, and botanical extracts such as 200 ppm of garlic clove extract, 200 ppm of neem extract and 200 ppm of eucalyptus extract, were assessed. Six treatments and four replicates were employed in a completely randomized design for this present study. The natural occurrence of leaf diseases was taken into account in the experiment. Disease incidence (%), disease severity (%), number of leaves per plant, plant height (cm) and number of branches per plant were recorded seven weeks after transplanting. Analysis of variance was used to assess the significance of treatment effects. The findings confirmed that the exogenous spraying of salicylic acid and garlic clove extract significantly (P<0.05) decreased the disease severity and incidence, with statistically equivalent efficiency for both substances. Moreover, number of branches per brinjal plant (3.3), plant height (51.4 cm) and number of leaves per brinjal plant (31.5) were significantly (P<0.05) enhanced by salicylic acid compared to control. Hence, spraying garlic clove extract and salicylic acid may therefore be an environmentally potential means of managing brinjal leaf diseases during the vegetative growth stage.

Revolutionizing Potato Farming: Dynamic Innovations Reshaping Late Blight Control in Pakistan

Potato (Solanum tuberosum L.) is one of the most extensively cultivated crops around the world, and Pakistan’s weather favor production and cultivation. Despite the ease of cultivating potatoes and the nominal labor supplies, Pakistan’s output of potatoes has not yet achieved a promising level when compared to nearby nations like India and Bangladesh. The crop's low production in Pakistan is caused by several biotic and abiotic stresses that instigated several pathogenic diseases such as early blight, bacterial wilt, viral infections, nematode infestations and late blight. Late blight disease is one of the most dreaded diseases of potatoes globally. It is caused by the fungus Phytophthora infestans which is highly adaptive to fungicides. Several fungicides have been in use against this disease for a long time, however, it has developed a high degree of resistant strains to these fungicides due to their unselective use over time and ultimately may cause colossal losses to the crop. In response, scientists have developed different potato varieties like Setanta, Nicola, Cara and Acoustic that are highly resistant to late blight. Similarly, cultural methods are also employed to combat late blight disease. This article provides an overview of the implications of late blight disease in potato cultivation and explores various strategies to reduce yield losses brought on by this disease via the application of synthetic fungicides.

Epidemiology and control of strawberry powdery mildew: a review

Strawberry powdery mildew, caused by Podosphaera aphanis, is an economically important disease for strawberry production. Typical symptoms are white mycelium on all aerial parts of affected plants, with young host tissues being the most susceptible. The pathogen overwinters on infected leaves, either as mycelium or chasmothecia, although the quantitative role of chasmothecia in epidemics are not fully understood. In spring, under favourable conditions, the fungus sporulates, disseminating conidia and causing polycyclic infections. The disease is mainly controlled using synthetic fungicides, but there is increasing interest in sustainable alternatives, including microbial biocontrol agents (e.g., Ampelomyces quisqualis, Bacillus spp., Trichoderma spp.) and substances of plant or animal origin (e.g., Equisetum arvense, orange oil, chitosan, whey). Physical methods, (e.g. UV-C, ozone) are also promising alternatives to fungicides. All of these strategies should be combined with appropriate agronomic practices (e.g., overhead irrigation, canopy management) to create unfavourable environments for the pathogen. However, agronomic practices have never been assessed for P. aphanis. Disease forecasting models and DSSs, though available, are underutilized due to their complexity and lack of validation across locations. This review presents the current state of knowledge on P. aphanis the available methods for control of strawberry powdery mildew, and highlights knowledge gaps relating to this host/pathogen relationship.

Effect of antifungal botanical extracts on seed-borne fungi prevalence and germination of Terminalia ivorensis seeds in Ghana

The use of synthetic fungicides for the management of seed-borne pathogens are detrimental to human health and the environment. In view of this research was conducted to assess the effect of antifungal botanical extracts (garlic, neem and Senna alata) on seed-borne fungi prevalence and seed germination of Terminalia ivorensis seeds. Two major seed-borne fungi of two genera namely Aspergillus niger and Colletotrichum sp. were isolated from the seeds. There was a hundred percent incidence of seed-borne fungi infection of Terminalia ivorensis seeds. Aspergillus niger was predominant with an incidence of 91.7% while Colletotrichum sp. had an incidence of 8.3%. There were significant differences between treatments with respect to total seed-borne fungi prevalence. Seeds treated with Senna alata aqueous extract showed the highest 100.0% prevalence of total seed-borne fungi followed by seeds treated with neem (75.0%) whilst seeds treated with aqueous garlic extract recorded the least (8.3%) total seed-borne fungi prevalence. The highest (100.0%) prevalence of Aspergillus niger was recorded by seeds treated with Senna alata whilst the least (8.3%) recorded in seeds treated with garlic. Colletotrichum sp. was only prevalent on seed treated with Mancozeb 80% WP at 8.3%. Significant variations were observed between treatments regarding germination percentages of Terminalia ivorensis seeds. Seeds treated with garlic extract recorded the highest (50.0%) germination percentage whilst the lowest (21.7%) recorded by Senna alata. Treating forest tree seeds with garlic extract before sowing could inhibit the growth of fungal pathogens and therefore improve germination.

ASSESSMENT OF PLANTS’ LEAF EXTRACTS FOR ANTIFUNGAL ACTIVITY AGAINST THE FUNGUS COLLETOTRICHUM ACUTATUM IN CHILI (CAPSICUM ANNUUM L.)

In horticultural crops, including chili, the wide use of synthetic fungicides has manifested to control anthracnose disease; however, these chemicals have some side effects to deal with. In reducing the dependency on synthetic fungicides, other alternatives and means need searching to prevent pathogenic fungi. Therefore, the presented study sought to examine plant extracts with the potential to inhibit the growth of pathogenic fungi Colletotrichum acutatum, the causal organism of anthracnose disease in chili. This study collected 20 potential plant species for the investigation. The leaf extraction used the maceration method in methanol and n-hexane. The contents of chemical compounds sustained the GC-MS analysis. All the leaf extracts tested for their bioactivity underwent the colony method and diffusion well. The results revealed that out of 20 types of plants, six plant species were capable of inhibiting the growth of C. acutatum fungi, including Piper nigrum, Piper ornatum, Piper retrofractum, Ficus septica, Samanea saman, and Tithonia diversifolia. The leaf extract of F. septica has the highest inhibition rate (81.11%) for the growth of C. acutatum compared with other plant leaf extracts. The GC-MS analysis of the F. septica leaf extract showed the presence of 15 types of metabolite constituents, with nine having antimicrobial activities.

Efficiency of Some Abiotic and Biotic Agents on Vicia faba L. Rust and Chocolate Spot Diseases

A variety of soil- and air-borne pathogens can attack faba bean plants, leading to rust and chocolate spot diseases that seriously affect plant yield. This study aims to evaluate the efficacy of certain essential oils as abiotic agents and biotic agents as safe alternatives to fungicides for both diseases. Double foliar applications of these essential oils and biotic agents significantly reduced the development of faba bean rust and chocolate spot incidence. The highest reduction in faba bean rust (92.7%) was achieved after spraying with jojoba oil, followed by 88.9% and 85.3% for grape and bitter orange oils, respectively. Furthermore, biotic inducers such as Bacillus subtilis, Trichoderma harzianum, and Saccharomyces cerevisiae reduced chocolate spot incidence by 100.0%, followed by a 72.3% reduction with bitter orange, thyme, black seed, and jojoba oils. The second foliar treatment with B. subtilis, T. harzianum, black seed oil, jojoba oil, and chitosan increased faba bean protein contents more than the first treatment. Individual foliar sprays with chitosan and grape oils enhanced catalase (CAT) specific activity, with the highest levels achieved after the first and second foliar applications, respectively. S. cerevisiae and lemongrass oil induced the highest peroxidase (POD) specific activity after both spray applications. Black seed oil induced the highest chitinase (CHIA) specific activity after the first foliar application, while lemongrass oil achieved the highest level after the second spray. The second foliar application of moringa oil, black seed oil, jojoba oil, chitosan, B. subtilis, and S. cerevisiae stimulated the formation of new protein bands in treated faba bean plants, which were not found after the first application. Therefore, the abiotic and biotic agents used in this study could be considered good and safe alternatives for resistance against these foliar diseases, reducing the harmful effects of synthetic fungicides.

Effectiveness of Four Synthetic Fungicides in the Control of Post-Harvest Gray Mold of Strawberry and Analyses of Residues on Fruit

Fungicides are usually applied on strawberries to manage gray mold, induced by the fungal pathogen Botrytis cinerea. In this study, four reduced-risk fungicides (formulations of pyrimethanil, PYR, 175 mL/hL; boscalid, BOS, 80 g/hL; combination fludioxonil, FLU, +cyprodinil, CYP, 110 g/hL) were applied before harvest for the management of post-harvest diseases of strawberries. The resulting fungicide residues on the strawberry fruit were also quantified. Strawberry fruits were harvested at 0, 4, 8, and 12 days following treatment (dft) and kept at 20 ± 1 °C for 4 days or cold-stored for 7 days at 0.5 ± 1 °C, followed by a 4-day shelf life at 20 ± 1 °C. All fungicides significantly reduced gray mold, according to the McKinney Index. At 0 dft and 4 days of shelf life, the FLU + CYP completely prevented post-harvest strawberry gray mold, while PYR and BOS reduced the disease by 88% and 42%, respectively, in comparison to the untreated control. For the duration of experiment, fungicide residues were always below the maximum residue levels, and FLU was the most degraded, thanks to the enzymatic pool of the strawberries. Monitoring fungicide residues in strawberries is essential to provide the consumer information on the safety of this widely consumed fruit. The present study points out the safety of strawberry fruits for consumers, even if the treatment strategy implies the use of fungicide mixtures before the consumption, with fungicide levels always being below the MRL.

Biological Control of Chili Anthracnose Disease using Talaromyces flavus Bodhi001

Background: Anthracnose disease of chili caused by Colletotrichum spp is one of the most destructive diseases affecting chili fruits in Thailand and significantly reduces fruit quality and chili production. Currently, this disease is managed primarily with synthetic fungicides that may affect public health and the environment adversely. Consequently, there is a need for biological management options. In vitro and in vivo evaluations of the antagonistic activity of Talaromyces flavus Bodhi001, Talaromyces trachyspermus Bodhi002, Talaromyces flavus Bodhi003 and Neosartorya fischeri Bodhi004 against Colletotrichum capsici, the causal agent of chili anthracnose disease, were conducted in the present study. Methods: The activity of antagonistic fungi against C. capsici was determined using PDA plate by dual culture method. The spore suspensions of C. capsici and antagonistic fungi were prepared in sterile water and adjusted using a hemocytometer to achieve a final concentration of about 106 spores mL-1. Result: The most effective antagonistic strains were T. flavus Bodhi001 and N. fischeri Bodhi004, which inhibited the mycelial growth of C. capsici by 68.99% and 70.76%, respectively. Interestingly, the antagonistic T. flavus Bodhi001 strain was the most effective at reducing the severity of chili anthracnose in vivo by up to 80%. The biological control activity of T. flavus Bodhi001 was to produce antibiosis against C. capsici; therefore, testing can be recommended to confirm its field trial stability. The results indicate that the application of the antagonistic fungi T. flavus Bodhi001 may be quite effective in biological control of chili anthracnose.

Polyphenols-Rich Extract of Calotropis procera Alone and in Combination with Trichoderma Culture Filtrate for Biocontrol of Cantaloupe Wilt and Root Rot Fungi.

Fungal diseases have always been a major problem for cantaloupe crops; however, synthetic fungicides are hazardous to humans and the environment. Consequently, a feasible alternative to fungicides without side effects could be by using bio agents and naturally occurring plants with antibacterial potential. This study has achieved a novel procedure for managing wilt and root rot diseases by potentially using Trichoderma sp. culture filtrates in consortium with plant extract of Calotropis procera, Rhizoctonia solani, Fusarium oxysporum, and Pythium ultimum, which were isolated from infected cantaloupe roots with identified root rot symptoms. The antagonistic activity of four Trichoderma isolates and analysis of antibiotics and filtrate enzymes of the most active Trichoderma isolate were determined as well as phytochemical analysis of C. procera plant extract using HPLC-UV. The obtained results showed that all Trichoderma isolates considerably lowered the radial growth of P. ultimum, R. solani, and F. oxysporum in varying degrees. The scanning electron micrographs illustrate the mycoparasitic nature of Trichoderma sp. on F. oxysporum. The phytochemical analysis of C. procera indicated that phenolic contents were the major compounds found in extracts, such as vanillin (46.79%), chlorogenic acid (30.24%), gallic acid (8.06%), and daidzein (3.45%) but including only a low amount of the flavonoid compounds rutin, naringenin, and hesperetin. The Pot experiment's findings showed that cantaloupe was best protected against wilting and root rot diseases when it was treated with both Trichoderma sp. culture filtrates (10%) and C. procera extract of (15 mg/mL), both alone and in combination. This study demonstrates that the application of bio agent Trichoderma spp. filtrate with C. procera phenol extract appears useful for controlling wilting and root rot disease in cantaloupe. This innovative approach could be used as an alternative to chemical fungicide for the control of wilting and rot root diseases.

Survey on the natural resistance to decay of five hundred tropical wood species

The natural durability of wood species against rot has again become a matter of interest for the uses of wood as a natural material, while the use of synthetic fungicides is being debated. In the mid-20th century, many experimental studies were performed in Europe and North America, using different standardised protocols. More than five hundred tropical wood species were tested in France between 1955 and 1990, with a total of 9,842 wood samples tested. It would seem useful to allow free access to all the data from these tests in the interests of a more comprehensive study of the natural durability of large wood panels. The great majority (68%) of all these tests used two slightly different protocols with only a change in woodblock test dimensions. Roughly half of the species were tested under one of the two protocols, and the other half under the second. In addition, certain species were tested with both protocols. The dimensions of the test blocks, the fungal strain used, and the wood type (sapwood or heartwood) all give significantly different results, but the mean mass loss due to the 4 main fungal strains is a good predictor of the wood resistance to rot. Overall, mass loss for sapwood with each protocol is 45% higher than for heartwood of the same species. There is a significant positive correlation between the rot resistance of the sapwood and the heartwood, but the decrease in heartwood compared to sapwood is greater in durable wood species than in non-durable ones. Heartwood rot resistance was observed to be highly variable between trees of the same species, except in those classified as “very durable” and “non-durable”. This opens up possibilities for a classification of natural rot resistance for numerous useful types of timber that are often regarded as only moderately resistant because they include a small proportion of species with poor resistance. Each protocol group included over one hundred species for which density and chemical composition data were available. Density, lignin content, and extractive content have a similar and very significant influence on the rot resistance of the wood (R² around 0.25).

A brief note on the incidence and management of Plasmodiophora rassica

Plasmodiophora brassica is a causal agent of brassica clubroot, and synthetic and bio fungicides showed actions against P. brassica. Under controlled-environment conditions, the mechanism of suppression of P. brassica by bio fungicides was antibiosis and mediated host resistance. To promote the delivery of bio fungicides, various formulations like granular and seed treatment were produced, so neither bio fungicides nor chemical fungicides were sufficiently compelling to reduce the population of resting spore P. brassica. Resistant cultivars substantially decreased clubroot intensity and canola yield losses. P. brassica resistance is the most consistent and economically appropriate management approach, but some studies indicate that clubroot resistance may not be robust. To build and deploy a different source of resistance constantly. The bait plants and soil modifications are not commercially practical. Crop data manipulation, soil fumigation, chemical fungicide application, and bio fungicides have much more ability to control P. brassica. The combinations of strategies that can minimize the pressure of disease in infested areas and enhance the resilience and number of the resistant gene versus P. brassica still need to be identified.

Ecological control of mycotic pathogens in tomato crops - alternatives to synthetic pesticides

The pathogens Alternaria solani and Fusarium oxysporum f. sp. lycopersici are of significant interest from a pathogenic perspective in the context of tomato cultivation. This study focuses on evaluating the fungicidal and fungistatic effects of different synthetic substances and natural compounds on the development of these two investigated pathogens. The fungicidal agents employed comprised fosetyl aluminum at a concentration of 0.3%, azoxystrobin at 0.2%, and metiram at 0.3%, while the natural extracts investigated included those derived from European birthwort, celandine and sage, each tested at concentrations of 0.5%, 2%, 9%, and 15%. The assessment of mycelial growth inhibition was conducted utilizing Vincent’s formula. Additionally, the total polyphenol content (TPC) within the extracts was determined via the Folin-Ciocalteu spectrophotometric method in accordance with Frum et al. (2022). Furthermore, the antioxidant capacity of the extracts was evaluated using the DPPH radical scavenging method (2,2-diphenyl-1-picrylhydrazyl) and high-performance liquid chromatography (HPLC). Our research findings yielded noteworthy results, specifically, extracts derived from sage and celandine, particularly when present at a concentration of 15%, exhibited a fungistatic effect. This effect was particularly remarkable when compared to the performance of the synthetic fungicide azoxystrobin at a concentration of 0.2% when challenged with the Alternaria pathogen. These results suggest the potential utility of sage and celandine extracts as eco-friendly alternatives for mitigating fungal pathogens in tomato crops, warranting further investigation and consideration within agricultural practices.

Bioefficacy of Trichoderma harzianum and Chitosan Oligo-saccharin as Seed Coating to Control Fusarium oxysporum Disease in Peanut

Formulations of biological fungicides to replace synthetic fungicides, which are potent and effective in controlling wilt and root rot in Peanut plants have not been found, so the results of the study can be the latest information. The research aims to find the most effective formulation when cultivating Peanut plants with Seed Coating. Seed-coating treatment of T. harzianum and chitosan compounds is expected to be more effective in preventing or controlling the attack of Fusarium wilt disease on Peanut plants. The study was designed according to Randomized Group Design (RAK) with the treatment of Seed Coating T. harzianum and Chitosan nanoparticles (Chitosan olligosaccharin), with a Control Treatment Design without Seed Coating, Seed Coating T. harzianum, Seed Coating Kitosan, Seed Coating Kitosan + T. harzianum, Inorganic Seed Coating with 64% Metalaxil. The lowest intensity of wilting was still shown by the control treatment of 64% Metalaxil chemical pesticide, with an average wilting intensity of 23.5%, but the Seed Coating Kitosan + T. harzianum treatment was the closest with an average wilting rate of 31.5%, significantly different from the control wilting intensity which reached 92.5%. While the best control effectiveness after Metalaxil is also Chitosan + T. harzianum. Seed Coating Chitosan and T. harzianum also provide better dry weight of stalks than other Seed Coating treatments with an average of 5.1 Kg/Ha

Fungicidal activities of chitosan-stabilized copper nanoparticles on Magnaporthe oryzae, Rhizoctonia solani, and Phytophthora capsica

Pathogenic fungi are the most common causes of economic loss in crop production. Until now, synthetic fungicides are the most effective tools for management in agriculture, but they cause a severe impact on the environment as well as several side effects for human health. The use of synthetic fungicides is prohibited in organic agriculture; however, sulfur and copper fungicides are still permitted in organic farming. In this study, chitosan-stabilized copper chitosan nanoparticles (CS-CuNPs) were synthesized and characterized via UV-Vis analysis and scanning electron microscopy (SEM). Moreover, fungicidal activities of CS-CuNPs in the range of concentrations (00, 500, and 1000 mg/L) against several plant pathogenic fungi, including Magnaporthe oryzae, Rhizoctonia solani, and Phytophthora capsici, have been assessed via filamentous fugal growth inhibition. The results indicated that the size of CS-CuNPs ranged from 70 to 74 nm with the plasmon absorption peak at 600 nm, which implied the CS-CuNPs were successfully synthesized. Furthermore, CS-CuNPs effectively inhibited the growth of all three fungi at a concentration 1000 mg/L. Among the three species, Rhizoctonia solani was the most susceptible to CS-CuNPs, with the growth inhibitory effect at 100 mg/L. In conclusion, CS-CuNPs demonstrated a strong potential for the elimination of plant pathogenic fungi and further applications in agriculture.

Runoff of foliar-applied natural fungicides in aquaponics: Implications for fish and nitrification

Aquaponics is a method of producing food in a sustainable manner through the integration of aquaculture and hydroponics, which allows simultaneous cultivation of fish and economic crops. The use of natural fungicides are crucial to the sustainable control of diseases in aquaponics. We assessed the potential impacts of natural fungicides, such as clove oil and lecithin, as well as a synthetic fungicide, tebuconazole, following foliar application in aquaponics. This study examined the runoff rates of the fungicides in decoupled aquaponics, and the subsequent effects of the runoffs on nitrification processes and Nile tilapia (Oreochromis niloticus). The runoffs of the foliar-applied fungicides, clove oil, lecithin, and tebuconazole, were detected in aquaponics water at a percentage runoff rate of 0.3 %, 2.3 %, and 0.3–0.8 % respectively. In the biofilter, lecithin altered the ammonium levels by increasing ammonium-nitrogen levels by 7 mg L-1, 6 h post application. Clove oil, on the other hand, showed no significant effect on ammonium, nitrite, and nitrate-nitrogen. Similarly, the toxicity test showed that eugenol had no significant effects on the hematological, biochemical and antioxidative activities of O. niloticus. Conversely, tebuconazole exhibited significant and persistent effects on various biochemical parameters, including lactate, albumin, and total protein, as well as hematological parameters like hemoglobin and MCH. The use of lecithin and tebuconazole should only be limited to decoupled aquaponics.

ROS-mediated antifungal activity of Ocimum essential oil-loaded nanoemulsions against postharvest fungal pathogens of Kinnow

Kinnow fruit is prone to fungal and microbial attacks, leading to significant postharvest losses during marketing and storage due to two most prominent fungal pathogens, Penicillium digitatum and P. italicum. Safer alternatives of synthetic fungicides are required for management of these pathogens. Essential oils (EO) with remarkable antimicrobial activities may offer an upcoming alternative, but the high volatility, thermal sensitivity, and hydrophobicity limit their commercial applications. In the current study, coarse and nanoemulsions (CEs and NEs) of the most potent Ocimum species were evaluated as novel coatings for Kinnow. In a screening in vitro study, the efficacy of Ocimum essential oil of three species against P. digitatum and P. italicum was assessed. The CEs and NEs (0.5%–0.3% concentrations) of Ocimum viride EO (OVEO, best screened EO) with three surfactants in 1:1 oil-surfactant proportion (OSP) were prepared. The NE formulated with 1% oil having OSP (1:1) sonicated for 10 min exhibited consistent stability till 1 month with mean droplet diameter of 180.2 nm, polydispersity index 0.328, ζ-potential (−22.58 mV) and pH of 7.84) exhibited complete inhibition of hyphal growth of test fungi at 500 mg L−1. The EO-NE treatment of the fungal hyphae led to enhanced generation of reactive oxygen species (ROS) manifested as hyphal distortion and suppression of spore germination as compared to EO. OVEO NEs may offer an ecofriendly alternate to synthetic analogues for postharvest management of Kinnow.

Antifungal Activity of Streptomyces spp. Extracts In Vitro and on Post-Harvest Tomato Fruits against Plant Pathogenic Fungi

Plant pathogenic fungi are the most important cause of losses in agriculture. In the context of the overuse of synthetic fungicides, natural products are an encouraging alternative to control these plant pathogenic fungi. In this study, we tested the antifungal capacity of four strains of the genus Streptomyces against the plant pathogenic fungi Alternaria alternata, Botrytis cinerea and Fusarium oxysporum. We also investigated the effect of applying the extracts with the highest antifungal activities in a post-harvest setting for the control of B. cinerea on cherry tomato fruits. The results revealed the ability of these strains, especially Streptomyces netropsis A52M, to inhibit in vitro the growth and, in some cases, the sporulation of plant pathogenic fungi. The protective effect of the S. netropsis A52M extracts on post-harvest cherry tomato fruits infected with B. cinerea was demonstrated. In addition, when grown in co-culture, we observed an interesting phenomenon in which the Streptomyces mycelium physically encapsulated the fungal mycelium, contributing to its inhibition. This outcome offers the potential for research into the role of physical microbial interactions in fungal biocontrol. To sum up, the findings outlined here for the interactions between Streptomyces strains and plant pathogenic fungi are a promising, safer, and more sustainable biocontrol alternative to chemicals for agriculture. This is of particular interest in the protection of perishable agricultural products during the post-harvest phase.