Tomato Early Blight Research Articles

Three point mutations in AaCYP51 combined with induced overexpression of AaCYP51 conferred low-level resistance to mefentrifluconazole in Alternaria alternata

Tomato early blight is a significant disease that causes substantial losses to tomato yield and quality. Mefentrifluconazole, an isopropanol-azole subgroup of triazole fungicides, has been registered in China for controlling various plant diseases, including tomato early blight, grape anthracnose, and apple brown spot. However, limited information is available on the mefentrifluconazole resistance risk and mechanism in plant pathogens. The sensitivity to mefentrifluconazole of 122 isolates of Alternaria alternata, one of the causal agents of tomato early blight, collected from different provinces in China, was evaluated. The results showed a unimodal curve for the sensitivity frequency, with an average EC50 of 0.306 μg/mL. Through fungicide adaption, six resistant mutants (N4, N5, T4, T5, NG1, and NG10) were obtained from three parental isolates, with a mutation frequency of 3.28 × 10−4 and resistance factors ranging between 19 and 147. The survival fitness of the resistant mutants, except for NG1, was significantly lower than that of their parental isolates. Positive cross-resistance was observed between mefentrifluconazole and difenoconazole or fenbuconazole, whereas no cross-resistance was found with three non-DMI fungicides. Furthermore, three distinct point mutations were detected in the AaCYP51 protein of the resistant mutants: I300S in T4 and T5; A303T in N4, NG1, and NG10; and A303V in N5. Compared to the parental isolates, the AaCYP51 gene was overexpressed in all six resistant mutants when treated with mefentrifluconazole. In summary, the resistance risk of A. alternata to mefentrifluconazole was low, and point mutations and overexpression of the AaCYP51 gene were identified as contributing factors to mefentrifluconazole resistance in A. alternata.

Effect of biocides and essential oil nanoemulsions against tomato early blight disease under greenhouse and field conditions

Effect of biocides and essential oil nanoemulsions against tomato early blight disease under greenhouse and field conditions

Exploring the mechanisms of endophytic bacteria for suppressing early blight disease in tomato (Solanum lycopersicum L.).

Controlling early blight of tomatoes using endophytic bacteria is an eco-friendly and sustainable approach to manage this common fungal disease caused by Alternaria solani, Alternaria alternata, and Curvularia lunata. Endophytic bacteria are microorganisms that live inside plant tissues without causing harm and can help protect the host plant from pathogens. In this work, twenty endophytic bacterial isolates from tomato healthy plants were tested against pathogenic fungal isolates that caused early blight disease in vitro. Out of the 20 tested isolates, three (B4, B7, and B17) were considered effective isolates against the growth of fungal pathogens. The three isolates were recognized as Enterobacter cloacae HS-6 (B4), Pseudomonas gessardii HS-5 (B 7), and Pseudomonas mediterranea HS-4 (B17) using 16s-rDNA sequencing. Different concentrations of bacterial cultural diltrates at 20, 40, and 60% were tested for their antagonistic effects on the development of pathogenic fungi in vitro. The lowest dry weights of pathogenic isolates in all bacterial culture filtrates were discovered at 60%. In all culture filtrates, phenolic compounds showed the largest peak area. Under greenhouse conditions, the least disease severity of tomato early blight was found for E. cloacae and its culture filtrate compared to other treatments. Real-time PCR was used to examine the expression pattern of the defense response gene β-1.3 glucanase gene in infected tomato plants with pathogenic fungi (control) as well as its relations with efficient biocontrol agent (E. cloacae). The expression of the gene increased substantially and significantly after three days from the inoculation-infected plants with C. lunata and E. cloacae while it reached the maximum after five days from the inoculation with A. alternata, A. solani and E. cloacae. Our study concluded that the endophytic bacterial isolate E. cloacae can be considered a promising biocontrol agent for preventing tomato early blight.

Detection of Bangladeshi-Produced Plant Disease Using a Transfer Learning Based on Deep Neural Model

Plant diseases pose a significant threat to agricultural productivity and food security in Bangladesh. In this research, we address the challenge of timely and accurate plant disease detection through the application of transfer learning with deep neural models. We curated a diverse dataset comprising 18 categories of plant leaf images, including Bell pepper Bacterial spot, Bell pepper Healthy, Peach Healthy, Potato Early Blight, Rice Leaf Blast, Rice Healthy, Rice Brown Spot, Potato Healthy, Peach Bacterial spot, Corn Blight, Potato Late blight, Corn Healthy, Tomato Bacterial spot, Strawberry Leaf Scorch, Tomato Early blight, Tomato Early blight, Strawberry Healthy, and Tomato Healthy. The dataset represents the most prevalent plant diseases observed in the Bangladeshi context. We employed three state-of-the-art deep learning algorithms, EfficientNetV2M, VGG-19, and NASNetLarge, to develop robust plant disease detection models. Through transfer learning, these pre-trained models were fine-tuned on our specialized dataset to adapt them for the task at hand. The performance evaluation revealed impressive results, with EfficientNetV2M achieving an accuracy rate of 99%, VGG-19 achieving 93%, and NASNetLarge attaining 83% accuracy. The high accuracy of EfficientNetV2M showcases its exceptional capability in accurately classifying plant diseases prevalent in Bangladesh. The success of these deep neural models in detecting various plant diseases signifies their potential in revolutionizing plant disease management and enhancing agricultural practices. Our research contributes valuable insights into the effective use of transfer learning for plant disease detection and emphasizes the significance of dataset curation for improved model performance. The developed models hold promise in providing timely and precise disease diagnosis to farmers and agricultural professionals, thereby facilitating prompt interventions and minimizing crop losses. Future research can explore the integration of these deep neural models into practical agricultural tools, enabling real-time disease detection and offering substantial benefits to the agricultural industry in Bangladesh.

Synergistic biocontrol of Bacillus subtilis and Pseudomonas fluorescens against early blight disease in tomato.

Early blight of tomato caused by Alternaria solani results in significant crop losses. In this study, Bacillus subtilis J3 and Pseudomonas fluorescens J8 were co-cultured as a synthetic microbial community (BCA) for synergistic biocontrol of A. solani, and the inhibition mechanism was investigated. BCA presented an inhibition ration against A. solani at 94.91%, which lowered the disease incidence by 38.26-42.87%; reduced peroxidase, catalase, superoxide dismutase activity of tomatoes by 73.11-90.22%; and promoted the biomass by 66.91-489.21%. With BCA protection, the relative expression of tomato resistance genes (including gPAL2, SWRKY, PR-10, and CHI) in roots and leaves was 12.83-90.70% lower than without protection. BCA also significantly altered the rhizosphere and phyllosphere microbial community. The abundance of potentially beneficial bacteria, including Bacillus, Pseudomonas, Arthrobacter, Lysobacter, and Rhizobium, elevated by 6.58-192.77%. They were negatively correlated with resistance gene expression, indicating their vital involvement in disease control. These results provided essential information on the synergistic biocontrol mechanism of bacteria against pathogens, which could contribute to developing novel biocontrol strategies. KEY POINTS: • Bacillus and Pseudomonas present a synergistic biocontrol effect against A. solani. • Biocontrol prevents pathogen damage and improves tomato growth and systemic resistance. • Beneficial bacteria thrive in the rhizosphere is the key to microbial regulation.

Screening and identification of antagonistic fungi against tomato early blight and research on its pot-plant control effects

Screening and identification of antagonistic fungi against tomato early blight and research on its pot-plant control effects

Detection of Early Blight Tomato Leaf Using k-Means Clustering

Early blight is one of the major diseases of tomatoes that affects the leaves and fruit quality. Detection and estimation of the disease severity are performed using the visual observation method. Visual detection requires significant time for visual inspection of a large cultivated area. Thus, image processing techniques have proven to be an effective method as compared to visual analysis. In this study, digital image processing methods and techniques were used to detect early blight of tomato (EBT), estimate the disease severity, and classify tomato leaves. Totally, 198 infected plants were randomly taken from the Haramaya University research site "Rare" at four different times. Diseased potato leaf images were captured, resized, and stored for experimentation. The stored images were processed using median filtering to remove noise while preserving useful features in an image and image enhancement. The RGB images were transformed to gray scale and CIELAB color space, and the k-means clustering was applied to estimate the disease severity of the potato leaves, and Otsu’s thresholding algorithm was applied to estimate the disease severity of both the detached and live leaves. MATLAB algorithms will be developed to determine the total area and infected lesion area of the leaf samples.

Biocontrol Potential of Lipopeptide Bio Surfactant Produced by Bacillus sp. from Mangrove Ecosystem at Vellar-Coleroon Estuarine Complex against Early Blight of Tomato

Biocontrol Potential of Lipopeptide Bio Surfactant Produced by Bacillus sp. from Mangrove Ecosystem at Vellar-Coleroon Estuarine Complex against Early Blight of Tomato

Lipopeptide-enriched extracts of Bacillus velezensis B157 for controlling tomato early blight

Bacillus strains used in plant disease control produce cyclic lipopeptides (LPs) with antifungal activities. The LP concentration in Bacillus-cell suspensions may be insufficient to protect aerial plant parts against phytopathogens and the de novo metabolite production by bacteria on leaf surfaces is limited, leading to inconsistent control results in the field. We investigated the use of LP-enriched crude organic extracts of Bacillus velezensis strain B157 for controlling early blight, a destructive tomato disease caused by Alternaria linariae. Liquid chromatography–tandem mass spectrometry-based LP dereplication and molecular networking analysis revealed a complex mixture of iturins, fengycins, and surfactins in the organic extract of B157. Fengycins and iturins showed a marked in vitro antifungal activity. Treating tomato plants with the organic extract significantly reduced the severity of early blight, attaining more than 90% of disease control efficacy in two independent greenhouse experiments. These results show the potential of using LP-enriched biochemical fungicides for plant disease control.

Genome Sequence Resource of Curvularia clavata Causing Leaf Spot Disease on Tobacco by Oxford Nanopore PromethION.

Genome Sequence Resource of Curvularia clavata Causing Leaf Spot Disease on Tobacco by Oxford Nanopore PromethION.

Screening of tomato (Solanum lycopersicon L.) genotypes by inducing systemic resistance against early blight disease caused by Alternaria solani

Early blight of tomato (Solanum lycopersicon L.) incited by Alternaria solani is highly destructive disease in the world. Environmental factors significantly impact early blight epidemics, leading to the loss of up to 78 per cent of tomato production. Twenty tomato genotypes were used in this study to identify the early blight resistant and susceptible genotypes selected to represent a range of reactions when screened under field conditions. The tomato plants were evaluated for early blight disease by using Per cent Disease Index (PDI). Pusa Uphar (20.18%) and Sankaranti (20.18%) showed resistance to early blight disease among the twenty genotypes. Anaka Kerala (61.25%), Arka Vikas (61.76%), Pusa Rohini (53.65%), Ashoka (50.60%) and Paiyur1 (56.08%) genotypes were found highly susceptible based on early blight disease intensity. Spore inoculation of A. solani was sprayed into tomato plants, it was discovered that the number of defense-inducing compounds viz., total phenols, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) has increased. Among the genotypes, Pusa Uphar (T2) and Sankaranti (T1) genotypes showed a high level of defense enzyme production. After tomato plants were exposed to pathogens through artificial inoculation, the activity of these defensive enzymes and compounds was highly induced in the resistant and sensitive germplasm than in the control.

Evaluation of In Vitro and In Vivo Antifungal Activity of Green Synthesized Silver Nanoparticles against Early Blight in Tomato

Silver nanoparticles have gained considerable interest in recent decades due to their antimicrobial activity and are used in water disinfection, wound healing, food packaging, and plant protection. This study tested the potential of silver nanoparticles synthesized using the neem (Azadirachta indica) leaf extract against Alternaria solani causes early blight disease in tomato plants. The pathogen was isolated from infected tomato plants and identified using morphological and molecular features. The results showed significant variation among isolates. Isolates, Shk-1 and Ksr-1 were highly pathogenic, causing up to 80% disease incidence. The potential of silver nanoparticles against each isolate was determined using different concentrations of silver nanoparticles. During in vitro and in vivo experiments, the growth inhibition rate of the pathogen was 70–100% at 50 ppm. Lower concentrations of silver nanoparticles (5 and 10 ppm) increased phenolics, PO, PPO, and PAL production by more than 50% as compared to the untreated control. These defensive mechanisms clearly demonstrate the fungicidal potential of AgNPs and recommend their utilization in different crop protection programs.

Antifungal activity against Alternaria solani and control of early blight in tomato by essential oil of citronella

Antifungal activity against Alternaria solani and control of early blight in tomato by essential oil of citronella

Farmers perception on pest management practices and profitability analysis for five winter vegetable production

The purpose of the study was to determine the farmers' perceptions of management measures against insect and disease pests and the profitability of five winter vegetables grown in Bangladesh's Sirajganj area. The highest incidences of fungal infections, including curd rot of cauliflower and early blight of tomato, were discovered. One of the most destructive diseases of brinjal and tomato was wilt, which was caused by both fungi and bacteria. Farmers took the necessary steps to control aphids (40-150 insects m–2 or 20-50 infected shoots m–2), brinjal shoot and fruit borer (10-50 insects 10m–2 or 20-60 infected shoots or fruits 10m–2), and other insects at the threshold level. They employed physical, chemical, and Integrated Pest Management (IPM) techniques to manage the disease and insect pests. The greatest amount of insecticide spraying (35-45 times) was performed to control brinjal shoot and fruit borer insects. The entire manufacturing cost followed the pattern tomato > brinjal > bean > cauliflower > bottle gourd. The cultivation of brinjal yielded the highest return, gross margin, and net return (Tk. 987,000.00, Tk. 800,572.00, and Tk. 763,117.00 ha–1, respectively; US$ 1 = Bangladesh currency Tk. In contrast, bottle gourd farming yielded the lowest return (Tk 700,000.00 ha–1), and tomato cultivation yielded the lowest gross margin and net return (Tk 539,152.00 and 507,325.00, respectively). The brinjal cultivation had the highest profitability index, benefit-cost ratio (both variable and total cost basis), and rate of return on investment, whereas tomato cultivation had the lowest. Rot, blight disease, shoot and fruit borer, or fruit borer, and aphid were the most common pests of winter vegetables in the region surveyed. Finally, we discovered that brinjal is the most profitable vegetable in our area of study.

Antifungal potential of volatiles produced by Bacillus subtilis BS-01 against Alternaria solani in Solanum lycopersicum.

Bacterial biocontrol agent/s (BCAs) against plant diseases are eco-friendly and sustainable options for profitable agricultural crop production. Specific beneficial strains of Bacillus subtilis are effective in controlling many fungal diseases including Alternaria blight caused by a notorious pathogen "Alternaria solani". In the present study, the biocontrol attributes of a newfangled strain of B. subtilis (BS-01) have been investigated and its bioactive compounds were also identified against A. solani. The volatile organic compounds (VOCs) produced by BS-01 in organic solvents viz., n-hexane, dichloromethane, and ethyl acetate were extracted and their antifungal efficacy has evaluated against A. solani. Also, the preventive and curative biocontrol method to reduce the fungal load of A. solani was estimated by both foliar and seed applications on infected tomato (Solanum lycopersicum) plants as determined by quantitative PCR assays. Growth chamber bioassay revealed that both foliar and seed application of BS-01 on tomato plants previously or subsequently infected by A. solani significantly reduced the pathogen load on inoculated tomato foliage. Results showed that antifungal bioassays with various concentrations (10-100 mg mL-1) of extracted metabolites produced by BS-01 in ethyl acetate fraction showed the highest inhibition in fungal biomass (extracellular metabolites: 69-98% and intracellular metabolites: 48-85%) followed by n-hexane (extracellular metabolites: 63-88% and intracellular metabolites: 35-62%) and dichloromethane (extracellular metabolites: 41-74% and intracellular metabolites: 42-70%), respectively. The extracted volatile compounds of BS-01 were identified via GC-MS analysis and were found in great proportions in the organic fractions as major potent antifungal constituents including triphenylphosphine oxide; pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(phenylmethyl); n-hexadecanoic acid; n-tridecan-1-ol; octadecane; octadecanoic acid; eicosane and dodecyl acrylate. Separate or mixture of these bioactive VOCs had the potential to mitigate the tomato early blight disease severity in the field that would act as a sustainable plant protection strategy to generate profitable tomato production.

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 OMRI-certified fungicides and chitosan for managing early blight caused by Alternaria solani and Septoria leaf spot in tomato

Field studies to evaluate the efficacy of OMRI-certified fungicides and other materials for control of early blight caused by Alternaria solani and Septoria leaf spot of tomato were conducted in Lexington, Kentucky during 2009 and 2010. Nine fungicides as well as ammonium bicarbonate and chitosan were evaluated in an organic production system. The most effective fungicides for managing Septoria leaf spot and early blight of tomato were copper based. None of the biological-based products (Sonata® and Serenade Max®), plant-based extracts (Trilogy® and Regalia® SC), chitosan, ammonium bicarbonate nor horticultural lime sulfur provided a significant (P>0.05) reduction in disease severity. However, despite significant (P<0.05) disease control in plots treated with copper-based products, no significant (P>0.05) improvement in yield over the untreated control was observed during the first two experiments in which the initial symptoms of foliar disease were observed after fruits were set. In the third field trial, in which initial symptoms were observed before fruit set, Serenade Max®, Bordeaux mixture, Regalia® SC, water-soluble chitosan and lime sulfur improved yield, although none provided significant disease control. These results suggest that, when necrotrophic foliar disease develops after fruit set, fungicides may have no effect on yield. In addition, some OMRI-certified fungicides may improve tomato yields by unknown mechanisms that do not involve disease control.

The efficacy of various fungicides against the tomato early blight (Alternaria solani)

The tomato is one of the most popular vegetables farmed worldwide. One of the most harmful tomato diseases is early blight, which is a disease that the fungus Alternaria solani causes.This will reduce the quality and quantity of tomatoes. Nearly 80% losses were reported due to this disease. To evaluate the fungi-toxic activity of the fungicides Kavach, Cbrio Top, Merivon, Avtar, Amistar, and Tilt at the plant pathology department of the faculty of agriculture at LPU, Punjab, over the years 2021–2022, the poisoned food approach was adopted. Six different fungicides were checked at different concentration like 50, 100, 150 ppm at lab condition. Propiconazole (Tilt) was found to be most effective, i.e. percent inhibition was 100%. Same fungicides were checked at field.Among this fungicides Cbrio Top, Merivon, Amistar were found to be most effective followed by kavach, Tilt and Avtar.

60%烯肟菌胺?丙森锌水分散粒剂对番茄早疫病的田间药效试验

60%烯肟菌胺?丙森锌水分散粒剂对番茄早疫病的田间药效试验

Management of tomato early blight [Alternaria solani (Ellis & Martin) Sorauer] through botanicals and fungicides under in-vitro and in-vivo conditions

Early blight is the most harmful and dangerous disease of tomato worldwide. In the present investigation, five plant extracts and five fungicides were evaluated against Alternaria solani under in-vitro condition and effective botanicals and fungicides were evaluated under field condition. Among all the botanicals, Azadirachta indica leaf was found most effective botanicals under in-vitro evaluation followed by Datura fastuosa leaf and Allium cepa leaf. Among the fungicides, minimum mycelial growth of Alternaria solani was found in Fluciazole 40% followed by Carbendazim 50% WP, Difenoconazole 25% EC, Azoxystrobin 23% SC and Mancozeb 75% WP. In field experiment, Fluciazole 40% EC and Carbendazim 50% WP found most effective among all the treatments.