Application Of Synthetic Fungicides Research Articles

Selecting Bacillus strains antagonist to Erysiphe necator (Schw.) Burr. the causal agent of grape powdery mildew

ABSTRACT Grape powdery mildew (GPM) control is based on the preventive use of sulfur and curative application of synthetic fungicides, increasing the risk for producers’ health and environmental and fruit contamination. This work aimed to select Bacillus strains isolated from the Brazilian tropical semi-arid region that are effective antagonists to GPM. In an initial screening performed by spraying bacterial suspensions in detached grape leaves, six strains of Bacillus spp. showed disease symptom reduction higher than 70.0%. Two greenhouse experiments showed that the bacterial strains LCB03, LCB28, and LCB30 showed control efficiency >80%, statistically similar to a commercial formulation with Bacillus amyloliquefaciens QST713. 16s rDNA sequencing showed that strain LCB03 showed 100.0% homology to B. velezensis, while LCB28 has high homology to B. tequillensis (99.93%), and LCB30 had 99.71% homology with B. siamensis. As an average for both greenhouse experiments, weekly application of Bacillus sp LCB03, Bacillus sp LCB28, and Bacillus sp. LCB30 reduced the average incidence by around 50% and more than 80% for GPM severity.

Marine actinomycetes for biocontrol of Fusarium solani in tomato plants: In vitro and in vivo studies

Using microorganisms as biocontrol agents of phytopathogens has been an alternative to synthetic fungicides. Actinomycetes isolated from soil and plants have reduced diseases caused by phytopathogens; however, microorganisms from marine environments may be an option as biocontrol agents. The tomato crop possesses an important economic impact worldwide, being Mexico the main exporter. Several species of Fusarium cause damage to tomato crops and are controlled with synthetic fungicides. The objective of this work was to determine the effect of marine actinomycetes as biocontrol on Fusarium solani in tomato plants. Four strains of marine actinomycetes (A20, A19, A18, and A15) and one terrestrial actinomycete (ED48) were used. The actinomycetes strains used, produced siderophores. The greatest inhibition of mycelial growth of F. solani due to iron competition was obtained by strain A19 with 74.28%. Only two actinomycetes showed antifungal activity by VOCs (A19 and A18), strain A19 showed the highest antagonistic activity with PICR of 76.75%. Actinomycetes treatments showed significant differences with synthetic fungicide application in growth, disease severity (SE), and disease incidence (DI) variables. The application of marine actinomycete (A19) on plants infested with F. solani increased the levels of enzyme activity (SOD, POD, CAT, and PAL) versus plants in that only F. solani and distilled water (control) were applied. Actinomycetes of marine origin are an option as biocontrol agents for F. solani.

Evaluation Of the Antifungal Activity of Cassia fistula (Linn) On Phytopathogenic Fungi Isolated from Citrus sinensis

Citrus sinensis is a prominent tropical fruit with nutritional and economic benefits for humans. However, it can also be plagued by fungal diseases, causing global economic and production reduction. The extensive application of synthetic fungicides in agricultural systems has posed increased toxicological risks to humans and ecosystems. However, the varying phytochemicals found in medicinal plants have enabled them to be regarded as safe and effective alternatives. However, few studies have evaluated the use of Cassia fistula extracts as potential bio-fungicides. This research purposed to evaluate the antifungal activity of Cassia fistula leaflet extracts against phytopathogenic fungi. Ethanol as well as aqueous extracts of Cassia fistula leaves were assessed for antifungal activity. The agar well-diffusion technique was implemented for in vitro screening, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of all different extracts against isolated fungal species of Aspergillus, Penicillium and Geotrichum. All fungal isolates identified from the spoiled oranges were Aspergillus flavus, Aspergillus fumigatus, Geotrichum sp. and Fusarium sp. Preliminary phytochemical screening exhibited the presence of carbohydrates, terpenoids, quinones and saponins in both ethanolic and aqueous extracts. At 1000 mg/ml, the aqueous and ethanolic extracts had the highest antifungal activity against A. flavus (40 mm) and Fusarium sp. (38 mm), respectively. Both extracts had no antifungal activity against A. fumigatus at 62.5 mg/ml but zones of inhibition were observed from the positive and negative controls of ketoconazole and DMSO, respectively. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were evaluated at 62.5 mg/ml and 250 mg/ml, respectively. This study’s findings demonstrated the antifungal potential of C. fistula leaf extracts as a bio-fungicidal agent against fungal invasion in plants.

Sustainable biocontrol of purple blotch disease in Allium cepa L. by biocontrol yeasts, Pichia kluyveri and Filobasidium wieringae

BackgroundPurple blotch disease is a devastating disease, resulting in significant yield losses in onion. Application of synthetic fungicides is a rapid approach for the control of this disease, but extensive use of synthetic fungicides results in resistance development in pathogen. Thus, it is mandatory to explore alternative approaches to overcome the fungicide resistance challenges. The present study focused on a sustainable biocontrolling approach by using biocontrol yeast. The objective was to develop a management strategy that offers an environmentally acceptable alternative to commonly used fungicides.ResultsA total of six pathogenic isolates were obtained from the infected onion leaves, out of all tested isolates, OP-4 recorded as highly virulent with disease incidence (75.2%). Filobasidium wieringae and Pichia kluyveri drastically reduced the in vitro mycelial growth of Alternaria porri (14 and 21 mm, respectively). In the greenhouse experiment, plant inoculated with P. kluyveri suspension was the most effective, resulting in considerable reduction (77.1%) in disease severity, before two days of pathogen inoculation. However, F. wieringae showed a considerable reduction (84.5%) in disease severity when applied in combination with P. kluyveri two days post-inoculation.ConclusionsThese findings highlighted the strong biocontrol potential of P. kluyveri and F. wieringae in managing the purple blotch disease of onion and can reduce the reliance on synthetic fungicides. Further research and field trials should be conducted to optimize the application methods and evaluate the long-term effectiveness of these bioagents.

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.

The efficient activity of plant essential oils for inhibiting Botrytis cinerea and Penicillium expansum: Mechanistic insights into antifungal activity

Botrytis cinerea and Penicillium expansum produce deterioration in fruit quality, causing losses to the food industry. Thus, plant essential oils (EOs) have been proposed as a sustainable alternative for minimizing the application of synthetic fungicides due to their broad-spectrum antifungal properties. This study investigated the efficacy of five EOs in suppressing the growth of B. cinerea and P. expansum and their potential antifungal mechanisms. EOs of Mentha × piperita L., Origanum vulgare L., Thymus vulgaris L., Eucalyptus globules Labill., and Lavandula angustifolia Mill., were screened for both fungi. The results showed that the EO of T. vulgaris and O. vulgare were the most efficient in inhibiting the growth of B. cinerea and P. expansum. The concentration increase of all EO tested increased fungi growth inhibition. Exposure of fungi to EOs of T. vulgaris and O. vulgare increased the pH and the release of constituents absorbing 260 nm and soluble proteins, reflecting membrane permeability alterations. Fluorescence microscopic examination revealed that tested EOs produce structural alteration in cell wall component deposition, decreasing the hypha width. Moreover, propidium iodide and Calcein-AM stains evidenced the loss of membrane integrity and reduced cell viability of fungi treated with EOs. Fungi treated with EOs decreased the mitochondria activity and the respiratory process. Therefore, these EOs are effective antifungal agents against B. cinerea and P. expansum, which is attributed to changes in the cell wall structure, the breakdown of the cell membrane, and the alteration of the mitochondrial activity.

Biocontrol of Penicillium digitatum by native Bacillus and Pseudomonas strains isolated from orange peel

Penicillium digitatum is a filamentous fungus that infects citrus fruits, causing decays that result in significant production losses. The application of synthetic fungicides is the main approach to control P. digitatum. However, intensive usage of fungicides has led to the proliferation of resistant P. digitatum strains. Besides, this practice poses a risk for the human and environmental health and is incompatible with organic markets. Alternative approaches that may overcome these limitations are valuable innovations for citrus production. The objective of this work was to evaluate the potential of bacterial strains inhabiting naturally in oranges to control the growth of sensitive and resistant to pyrimethanil P. digitatum strains.Around 50 bacteria were isolated from oranges peel but only three showed optimal antagonistic activity against sensitive P. digitatum after qualitative screening assays. These bacteria were identified by molecular and biochemical analyses and corresponded to Bacillus mojavensis SC-45, Bacillus velezensis SC-31 and Pseudomonas psychrotolerans SC-29. The antifungal activity of bacterial extracellular cultures against P. digitatum strains was quantified in vitro by the poison agar method and by measuring the mycelial growth at 600 nm in a microplate assay. B. velezensis SC-31 showed the highest growth inhibition of both P. digitatum strains. Lipopeptides with antifungal activity were identified by HPLC-ESI-MS in bacterial extracellular cultures. Surfactin and iturin were the most abundant lipopeptides produced by Bacillus spp., but higher yields were observed in B. velezensis SC-31 supernatant; whereas viscosin was mainly produced by P. psychrotolerans SC-29. B. velezensis SC-31 also showed the highest proteolytic activity and the highest capability to form biofilms. B. velezensis SC-31 and B. mojavensis SC-45 produced the lowest incidence and severity of disease in vivo after infection with both P. digitatum strains in preventive treatments. Besides, bacteria were compatible with concentrations of fungicides corresponding to maximum residue levels (MRL) on citrus fruits and higher concentrations used in drenches.B. velezensis SC-31 and B. mojavensis SC-45 are proficient antagonists to control green mould in oranges, which can be used together with fungicides to improve the inhibition of P. digitatum and avoid the emergence of resistant strains.

A review of biocontrol agents in controlling late blight of potatoes and tomatoes caused by Phytophthora infestans and the underlying mechanisms.

Phytophthora infestans causes light blight on potatoes and tomatoes, which has a significant economic impact on agriculture. The management of late blight has been largely dependent on the application of synthetic fungicides, which is not ultimate solution for sustainable agriculture and environmental safety. Biocontrol strategies are expected to be alternative methods to the conventional chemicals in controlling plant diseases in the integrated pest management (IPM) programs. Well-studied biocontrol agents against P. infestans include fungi, oomycetes, bacteria, and compounds produced by these antagonists, in addition to certain bioactive metabolites produced by plants. Laboratory and greenhouse experiments suggest a potential for using biocontrol in practical late blight disease management. However, the transition of biocontrol to field applications is problematic for the moment, due to low and variable efficacies. In this review, we provide a comprehensive summary on these biocontrol strategies and the underlying corresponding mechanisms. To give a more intuitive understanding of the promising biocontrol agents against P. infestans in agricultural systems, we discuss the utilizations, modes of action and future potentials of these antagonists based on their taxonomic classifications. To achieve a goal of best possible results produced by biocontrol agents, it is suggested to work on field trials, strain modifications, formulations, regulations, and optimizations of application. Combined biocontrol agents having different modes of action or biological adaptation traits may be used to strengthen the biocontrol efficacy. More importantly, biological control agents should be applied in the coordination of other existing and forthcoming methods in the IPM programs. This article is protected by copyright. All rights reserved.

Photodynamic Inactivation of Botrytis cinerea Spores by Curcumin—Effect of Treatment Factors and Characterization of Photo-generated Reactive Oxygen Species

AbstractBotrytiscinerea is the main cause of gray mold in a wide range of fresh produce, which causes huge losses in pre- and/or post-harvest stages and is therefore considered the second major plant pathogen globally. Since the application of synthetic fungicides is not allowed in postharvest conditions, alternative natural approaches are required to reduce the resulting spoilage. The aim of this study was to investigate the efficacy of photodynamic treatment in inactivating B. cinerea spores in vitro, for which the interactive effect of influential treatment parameters on curcumin phototoxicity was studied using an I-optimal design. Results showed that the antifungal activity of the treatment was significantly dependent on solvent, curcumin concentration, and irradiance, except for light dose. A complete photoinactivation of spores was obtained in an aqueous ethanolic environment (optimum condition: 13 μM, 31.75 mW cm−2, 19.05 J cm−2), compared to when curcumin was dissolved in medium-chain-triglyceride (MCT) oil. Furthermore, the photogeneration of superoxide anion and hydroxyl radicals was demonstrated by electron paramagnetic resonance spectroscopy, which indicates the occurrence of a type-I photodynamic reaction. These findings suggest that curcumin-based photosensitization can inhibit/reduce fungal infection, which can be employed in pre/post-harvest stages to reduce the waste caused by spoilage.

Perillaldehyde Functions as a Potential Antifungal Agent by Triggering Metacaspase-Independent Apoptosis in Botrytis cinerea.

Botrytis cinerea, the causal agent of gray mold, is an important plant pathogen causing preharvest and postharvest diseases. Due to the extensive use of commercial fungicides, fungicide-resistant strains have emerged. Natural compounds with antifungal properties are widely present in various kinds of organisms. Perillaldehyde (PA), derived from the plant species Perilla frutescens, is generally recognized as a potent antimicrobial substance and to be safe to humans and the environment. In this study, we demonstrated that PA could significantly inhibit the mycelial growth of B. cinerea and reduced its pathogenicity on tomato leaves. We also found that PA had a significant protective effect on tomato, grape, and strawberry. The antifungal mechanism of PA was investigated by measuring the reactive oxygen species (ROS) accumulation, the intracellular Ca2+ level, the mitochondrial membrane potential, DNA fragmentation, and phosphatidylserine exposure. Further analyses revealed that PA promoted protein ubiquitination and induced autophagic activities and then triggered protein degradation. When the two metacaspase genes, BcMca1 and BcMca2, were knocked out from B. cinerea, all mutants did not exhibit reduced sensitivity to PA. These findings demonstrated that PA could induce metacaspase-independent apoptosis in B. cinerea. Based on our results, we proposed that PA could be used as an effective control agent for gray mold management. IMPORTANCE Botrytis cinerea causes gray mold disease, is considered one of the most important dangerous pathogens worldwide, and leads to severe economic losses worldwide. Due to the lack of resistant varieties of B. cinerea, gray mold control has mainly relied on application of synthetic fungicides. However, long-term and extensive use of synthetic fungicides has increased fungicide resistance in B. cinerea and is harmful to humans and the environment. In this study, we found that perillaldehyde has a significant protective effect on tomato, grape, and strawberry. We further characterized the antifungal mechanism of PA on B. cinerea. Our results indicated that PA induced apoptosis that was independent of metacaspase function.

Farmers' perceptions on tomato early blight, fungicide use factors and awareness of fungicide resistance: Insights from a field survey in Kenya.

Early blight (EB) caused by Alternaria solani is one of the most devastating tomato diseases in Kenya and is most often managed by application of synthetic fungicides. However, there have been reports from farmers about the declining efficacy of some fungicides. These reports suggest that A. solani populations in Kenya could be developing resistance to some of the commonly used fungicides. In this study, we surveyed 175 tomato fields, sampled in 3 major tomato producing counties in Kenya, to determine the status of EB, management practices, and fungicide use factors that could contribute to development of resistance to fungicides among A. solani populations in Kenya. Data was recorded on farm characteristics, EB prevalence, fungicide usage, and farmers' perceptions on fungicide efficacy. EB was prevalent in 85% of the fields and 90% of the farmers identified it as a major cause of yield loss. Tomato was grown all year round on 60% of the fields with only short fallow periods. All farmers reported that they were relying on fungicides for EB control and none among the cultivars grown was resistant to the disease. A total of 40 fungicide products, representing 20 active compounds with varying FRAC resistance risk levels were in use against EB. Majority (83%) of the farmers were applying fungicides at dosages and frequencies higher than those indicated on labels. Most farmers (81%) indicated that they had observed declines in effectiveness of at least one fungicide, used at EB control. This observation was more with fungicides in the strobilurin and triazole groups. These findings demonstrate that the current tomato production systems in Kenya do not take into account the risk of A. solani developing resistance to fungicides. Enhancing farmers' knowledge of the disease and their ability to properly select and apply fungicides is therefore crucial for effective control of EB and mitigating the high risk of fungicide resistance build up.

Efficacy of Botanical Mixture and Fungicides to Combat Sigatoka Disease in Banana Cultivation

Black Sigatoka disease caused by Mycosphaerella fijiensis seriously threatens banana cultivation worldwide. This infirmity is controlled by the recurrent application of synthetic fungicides, which leads to several adverse effects. Plant extracts with antifungal potential have long been investigated as they contain secondary bioactive compounds for protecting crops from microbial infection. This study compared the antifungal activities of both botanical mixtures and recommended fungicides to control Black Sigatoka in banana. Laboratory and field studies were conducted to assess the antifungal activity of the botanical mix prepared from eight different herbal plant parts against M. fijiensis, with two recommended fungicides as the positive control. In vitro results showed that the radial growth of the fungus was significantly impaired (P<0.05.) by the addition of the botanical mixture, fungicides, and combination of the botanical mixture (BM) and fungicides in the PDA media. Mycosphaerella fijiensis differed in their reaction to the BM and fungicides, and combination of BM and fungicides, but on the whole, growth inhibition increased with the concentration. In field experiments, all the treatments reduced the disease incidence significantly compared to the unsprayed control, where the disease severity index (DSI) increased from 43.88 to 67.77 within 28 days. After the first spray, the botanical mixture and fungicides (Chlorothalonil and Carbendazim) reduced the disease severity index to 39.7, 41.19, and 44.44, respectively. Fungicides and combinations of Chlorothalonil + BM and Carbendazim + BM showed the lowest DSI, 34.07 and 35.83, respectively. The results show that combining the synthetic and botanical mixture is more effective for controlling the disease. The study reveals the possibility of utilizing a botanical mixture as an integrated approach to manage Black Sigatoka disease more efficiently and in an eco-friendly manner.

Actinomycete Potential as Biocontrol Agent of Phytopathogenic Fungi: Mechanisms, Source, and Applications.

Synthetic fungicides have been the main control of phytopathogenic fungi. However, they cause harm to humans, animals, and the environment, as well as generating resistance in phytopathogenic fungi. In the last few decades, the use of microorganisms as biocontrol agents of phytopathogenic fungi has been an alternative to synthetic fungicide application. Actinomycetes isolated from terrestrial, marine, wetland, saline, and endophyte environments have been used for phytopathogenic fungus biocontrol. At present, there is a need for searching new secondary compounds and metabolites of different isolation sources of actinomycetes; however, little information is available on those isolated from other environments as biocontrol agents in agriculture. Therefore, the objective of this review is to compare the antifungal activity and the main mechanisms of action in actinomycetes isolated from different environments and to describe recent achievements of their application in agriculture. Although actinomycetes have potential as biocontrol agents of phytopathogenic fungi, few studies of actinomycetes are available of those from marine, saline, and wetland environments, which have equal or greater potential as biocontrol agents than isolates of actinomycetes from terrestrial environments.

Application of nickel chitosan nanoconjugate as an antifungal agent for combating Fusarium rot of wheat

Agro-researchers are endlessly trying to derive a potential biomolecule having antifungal properties in order to replace the application of synthetic fungicides on agricultural fields. Rot disease often caused by Fusarium solani made severe loss of wheat crops every year. Chitosan and its metallic nano-derivatives hold a broad-spectrum antifungal property. Our interdisciplinary study deals with the application of nickel chitosan nanoconjugate (NiCNC) against Fusarium rot of wheat, in comparison with chitosan nanoparticles (CNPs) and commercial fungicide Mancozeb. CNPs and NiCNC were characterized on the basis of UV–Vis spectrophotometry, HR-TEM, FESEM, EDXS and FT-IR. Both CNPs and NiCNC were found effective against the fungal growth, of which NiCNC at 0.04 mg/mL showed complete termination of F. solani grown in suitable medium. Ultrastructural analysis of F. solani conidia treated with NiCNC revealed pronounced damages and disruption of the membrane surface. Fluorescence microscopic study revealed generation of oxidative stress in the fungal system upon NiCNC exposure. Moreover, NiCNC showed reduction in rot disease incidence by 83.33% of wheat seedlings which was further confirmed through the observation of anatomical sections of the stem. NiCNC application helps the seedling to overcome the adverse effect of pathogen, which was evaluated through stress indices attributes.

Evaluating the Efficacy of Gum Arabic-Zinc Oxide Nanoparticles Composite Coating on Shelf-Life Extension of Mandarins (cv. Kinnow).

Restricted postharvest application of synthetic fungicides in maintaining the quality of citrus fruits has led to a search for alternative postharvest treatments. This study evaluated the efficacy of gum arabic (GA) enriched with green synthesized zinc oxide nanoparticles (ZnO-NPs) in maintaining the postharvest quality of mandarin (cv. Kinnow). ZnO-NPs were synthesized using Bidens pilosa leaf extract and incorporated into GA (2% w/v) at 0, 0.25, 0.5, and 1% to form composite coatings: GA, GA + ZnO-NP 0.25%, GA + ZnO-NP 0.5% and GA + ZnO-NP 1%, respectively. Fruit were dipped for 3 min in the respective coatings, with untreated fruit used as control. Fruit were air-dried, packed in commercial cartons, and stored at 5 ± 1°C and 90 ± 5% relative humidity (RH) for 40 days and observed at 10 days intervals, plus 5 days at 20 ± 5°C and 65 ± 5% RH to determine the incidence of physiological disorders. GA + ZnO-NP showed promise as an alternative postharvest treatment for controlling postharvest physiological disorders associated with ‘Kinnow’ mandarin. For instance, GA + ZnO-NP 0.5% markedly minimized weight loss (9.2%), electrolyte leakage (43.8%) and chilling injury incidence (5.4%) compared to control (weight loss; 33.3%, electrolyte leakage; 90.3% and chilling injury incidence; 41.5%) at the end of the storage. GA + ZnO-NP 1% significantly alleviated rind pitting, with 13.2% incidence compared to 45.2% rind pitting incidence in the control fruit. This was due to significantly higher phytochemical and antioxidant capacity and reduced antioxidant enzyme degradation in coated fruit than in control. In conclusion, gum arabic coating enriched with ZnO-NPs at concentrations between 0.5 and 1% is recommended as a viable option to maintain the quality of ‘Kinnow’ mandarin fruit during cold storage.

Potential biocontrol mechanisms of Bacillus sp. TSO2 against Bipolaris sorokiniana, spot blotch in wheat

<p class="Default"><em>Bipolaris sorokiniana </em>is a pathogen of cereals such as wheat and barley, causing root rot, leaf blight, seedling blight, and spot blotch. This phytopathogen causes a considerable reduction in cereal yield of up to 85%. Thus, sustainable alternatives to the application of synthetic fungicides are determinants for the control of phytopathogens, such as the application of biological control agents. This study aims to identify the potential biocontrol mechanisms of the bacterial strain TSO2 by sequencing, annotation, and mining its genome. The draft genome of strain TSO2 was sequenced through the Illumina Miseq platform and presented 4,242,212 bp, 43.9% G+C content, 300,069 bp N50, 5 L50, 47 contigs, 96 RNAs, and 4,432 predicted coding DNA sequences. Besides, the presence of 86 CDS of agricultural importance involved in virulence, disease, defense, iron acquisition, and secondary and phosphate metabolisms was detected. On the other hand, seven putative secondary metabolite gene clusters involved in biocontrol activity were identified in the genome of strain TSO2. <em>Bacillus </em>sp. TSO2 contains a great number of biosynthetic gene clusters which supports its biocontrol activity against phytopathogenic fungi. Thus, this strain needs to be further studied as a potential bioactive ingredient for the biopesticide formulation due to its high potential as a biological control agent.</p>

TRICHODERMA ASPERELLUM AS A POTENTIAL BIOCONTROL AGENT AGAINST FUNGAL DISEASES OF CHILLI

: Fungal diseases are one of the major risks in chilli production. Plant diseases are being controlled commonly by the application of synthetic fungicides. Trichoderma species found to be most effective antagonism of foliar and soil borne pathogens. In the present study, dual culture assay was conducted against phytopathogenic fungi of chilli in vitro and examined percent inhibition by the potential biocontrol agent. Dual culture plate test revealed that the percentage growth inhibition of Colletotrichum gleosporoides, Fusarium oxysporum, Pythium apanidermatum, Curvularia lunata and Alternaria sp by Trichoderma asperellum were in the range of 26.4 to 83.5 %.T. asperellum, a less studied fungus, is also a successful biological control agent against a wide range of plant pathogens. Thus, the aim of this research is to assess the antagonistic ability of T. asperellum towards chilli phytopathogenic fungi under in vitro conditions. The antagonistic efficacy of T. asperellum can be exploited in the disease management of chilli in field conditions.

Eucalyptus staigeriana essential oil can control downy mildew in grapevine

Downy mildew (Plasmopara viticola) is the primary disease in viticulture worldwide, and your control requires synthetic fungicides applications to avoid quality and yield loss in the grapevines. However, alternatives to reduce synthetic fungicides are needed to ensure the consumer’s health and the environment. Essential oils (EOs) are amongst the most promising natural plant protection alternatives because of their antifungal properties on several crop diseases. The present study objective was to determine the effect of Eucalyptus staigeriana EO in vitro and in vivo against P. viticola. The EO exhibited the highest activity in vitro, inhibiting 90% of the incidence and severity of disease caused by P. viticola in leaves of grapevines in the greenhouse. In the field (in vivo), treatment with EO could not control the disease; however, treatment with EO in consortium with conventional treatment reduced approximately 50% of the incidence and more than 90% of the severity of downy mildew disease in leaves, decreasing the application of synthetic fungicides by 50%.

Antifungal Activity against Fusarium oxysporum of Botanical End-Products: An Integration of Chemical Composition and Antifungal Activity Datasets to Identify Antifungal Bioactives

Plants produce various compounds as defensive barriers to naturally control fungal diseases. Among them, vascular wilt caused by Fusarium oxysporum is one of the most destructive diseases in crops, causing relevant economic losses. The application of synthetic fungicides is the most used management for this disease. However, this kind of method also involves adverse environmental impacts. Therefore, alternative methods are continuously being developed as a strategy to be involved in integrated pest management programs. Thus, as part of our research on antifungals of plant origin, a group of botanical extracts was assessed for the respective inhibitory effect on mycelium and conidia of F. oxysporum. Mycelial growth inhibition was measured in 12-well plates containing amended semi-solid medium, whereas conidial susceptibility was determined through microdilution. The identification of the bioactive compounds among test extracts was performed using an indirect approach, consisting of the integration of chemical composition and antifungal activity datasets through single-Y orthogonal partial least squares (OPLS) regression. Results showed that Piper aduncum extract was the most potent mycelial growth inhibitor whereas P. elongatum exhibited the best effect on conidia susceptibility. The active compounds identified through statistical integration and subsequent isolation were piperaduncin C, asebogenin and (−)-methyllinderatin. These findings indicated that the integrative, indirect approach is useful for the identification of bioactive metabolites from botanical extracts to be further used as biological protective agents against this phytopathogen.

Nanovaccine for Plants from Organic Waste: d-Limonene-Loaded Chitosan Nanocarriers Protect Plants against Botrytis cinerea

Chitosan and d-limonene are bioactive molecules derived from organic waste. We repurposed them in the form of a drug delivery system for agricultural applications in crop protection to combatBotrytis cinerea, a broad host-range necrotrophic (BHN) pathogen that causes economic losses worldwide. Synthetic fungicide application remains the most common method to control this pathogen, but this comes with a significant environmental cost. Drug delivery systems from naturally occurring biomaterials can offer efficient treatment options to combat this pathogen. We hypothesized that engineered chitosan nanoparticles (CSNPs) loaded with d-limonene can trigger an on-demand systemic defense response in plants that enhances its quantitative disease resistance against BHN. Chitosan nanocarriers encapsulated with d-limonene as cargo were fabricated through a rational formulation via ionic gelation and the spontaneous emulsification method, respectively, to produce chitosan d-limonene nanoparticles (CdlNPs). The therapeutic effect of the d-limonene nanoemulsion, CSNPs, and CdlNPs on the plants’ defense response against necrotrophic fungal pathogens was evaluated by monitoring the dynamic morpho-physiological changes via multispectral image-based phenotyping in an Arabidopsis thaliana (Col-0)–B. cinerea model system. Functional analysis of the differentially expressed genes revealed that at the concentration of significant disease resistance (0.5%), CSNPs downregulated the biological process involved in plant growth and development, but upregulated the main process controlling response to stress.