Propolis extracts suppress early blight severity in tomato by enhancing antioxidant defenses and phenylpropanoid pathway

The early blight (caused by the fungus Alternaria solani) results in significant damage to the tomato crop, directly affecting productivity. An alternative to the frequent use of pesticides is the use of essential oils, which can act in defense against phytopathogens. The objective of this work was to evaluate the toxic activity in vitro of the bergamot orange (Citrus aurantium ssp. bergamia) essential oil against A. solani, the control of the early blight, and the activity of defense enzymes in tomatoes treated with this oil and inoculated with A. solani. Mycelial discs of A. solani were added to dishes with V8 culture media to which essential oil at concentrations of 0, 500, 1000, 1500, 2000, and 2500 µL L-1, in addition to a standard fungicide treatment (azoxystrobin + difenoconazole, 200 + 125 g L-1, respectively) was added. The Petri dishes were incubated at 25 °C in the dark. Mycelial growth was evaluated daily for 19 days, when all treatments reached maximum growth. Sporulation analysis was performed thereafter. Tomato plants were treated with bergamot essential oil, 30 days after transplanting, in the concentrations and fungicide mentioned, in the second pair of leaves. After 72 hours, the pathogen was inoculated using a spray bottle, on treated leaves (second pair of leaves) and untreated leaves (third pair of leaves). The area under the disease progress curve (AUDPC) was calculated based on five severity assessments. The activity of peroxidase (POX), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) was evaluated in leaves treated with the concentration of 2500 µL L-1 of essential oil. The concentration of 2500 ?L L-1 reduced mycelial growth and sporulation of the pathogen by 68.15% and 29.48%, respectively. In treatments with application of essential oil, lower AUDPC was observed for a concentration of 2500 ?L L-1, which was statistically similar to that observed for fungicide application, both in treated and untreated leaves. A greater activity of PPO, POX, and PAL was found locally and systemically, both in the second and third leaves, at concentration of 2500 ?L L-1. The essential oil of bergamot can be an alternative for the control of early blight in tomato.

Alternaria solani causing early blight of tomato is a serious disease, causing 50% to 86% losses in fruit yield and 20% to 40% losses in seedling establishment. Pathological survey, etiology and physiological characterization of the causal organism are necessary to formulate effective management strategy. Therefore, present study was conducted to determine the incidence and severity of early leaf blight of tomato in some selected area of Bangladesh and to evaluate the effect of different culture media on radial mycelial growth and sporulation as well as the effect of pH and temperature on mycelial growth. Survey was conducted in five upazilas of Bogura district and typical early blight disease sample was collected from surveyed field and Germplasm Centre, Agrotechnology Discipline, Khulna University, Khulna. Seven different culture media were used namely Potato Dextrose Agar (PDA), Richard’s Agar (RA), Waskman Agar (WA), Corn meal Agar (CA), Asthana and Hawker’s Agar (AHA), Oat Meal Agar (OMA), V-8 Juice Agar Medium (VJAM) and seven different pH level such as 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0 were used and also exercised five distinct temperatures such as 20°C, 25°C, 30°C, 35°C and 40°C to appraise cultural characters, mycelial growth and sporulation of A. solani. Cultural characters such as colony color, colony diameter, growth margin, growth surface and margin topography showed distinguished variation in culture media. Among the seven different media V-8 Juice Agar Medium gave not only maximum mycelial growth (73.10 mm) but also highest sporulation (2000 spores ml?1). The optimum pH for maximum mycelial growth ranged to 5.5 - 6.5. But maximum mycelial growth (71.70 mm) was observed in pH 6. Whereas, the mycelial growth was favored by 20°C - 30°C temperature but 25°C temperature provided highest mycelial growth (72.20 mm). However, temperature above 40°C was found adverse for the growth of tested fungus.

Antifungal activity and control of the early blight in tomato through tea tree essential oil

Bacillus pseudomycoides, Paenibacillus polymyxa, and B. velezensis are potent bacterial endophytes, which typically exhibit host-specific interactions. However, comparative studies of these endophytes in vitro and in planta in non-host crops are lacking. Therefore, in this study, we evaluated the potential of endophytes B. pseudomycoides strain HP3d, P. polymyxa strain PGSS1, B. velezensis strain A6, and P42, isolated from various crop ecosystems in promoting plant growth and inducing systemic resistance against early blight disease in tomato. In vitro, endophytes exhibited 44.44–55.56% and 37.50–87.50% inhibition of Alternaria solani in dual culture and volatilome bioassay, respectively. In the glasshouse, individual and combined applications via seed treatment (ST), seedling dip (SD), and foliar spray (FS) significantly enhanced shoot growth (23.63–57.61%), root growth (43.27–118.23%), number of leaves (77.52–93.58%), number of shoots (33.42–45.28%) and root dry matter (42.17–43.86%), reducing early blight (PDI) by 70.95–76.12% compared to uninoculated control. Enzymatic activities, including such as polyphenol oxidase (30–40 fold), peroxidase (65.00–75.00 fold), superoxide dismutase (34.20–37.20 fold) and phenylalanine ammonia-lyase (44.44–45.56 fold) were elevated post-inoculation in endophytes treated tomato plants challenged with A. solani compared to control treated only with A. solani and declined after the fifth day. The total chlorophyll content declined from the 0th to the 10th day, but endophyte treated plants exhibited lesser reductions (2.03–2.09) than uninoculated control. Field trials confirmed the glasshouse findings, showing reduced early blight and improved growth parameters in tomato where the ST + SD + FS combination emerged as the most effective treatment for all endophytes showing 1.06–1.88 fold increase in fruit yield per plant and 28.92–32.52% decrease in PDI compared to untreated control. Thus, the study highlights the broad-spectrum potential of these strains in promoting plant growth and controlling early blight in tomato, demonstrating non-host specificity. These endophytes offer eco-friendly alternatives to chemical pesticides, supporting sustainable agriculture. Their success in field trials suggests the potential for commercialization and large-scale use across diverse crops and pave the way for further interdisciplinary research to optimize their application in integrated pest management strategies.

Early blight is a common challenge to tomato production all over the world. Microbial antagonists, unlike synthetic chemicals, are friendly to the environment and human health. In this study, five microbial antagonists were evaluated for their effectiveness in managing the early blight of tomatoes under greenhouse and field conditions. Microbial antagonists included two Trichoderma isolates, two Bacillus subtilis isolates and one Pseudomonas fluorescens isolate. Water and Tower 72 WP® were used as control and reference test, respectively. Data were collected on disease parameters and tomato yield. All treatments significantly reduced the per cent disease index compared to the control in the greenhouse and in the field. The per cent disease index recorded for Tower 72 WP® was comparable to the per cent disease index recorded for most selected antagonists. All treatments recorded significantly higher yields compared to the control in the greenhouse and in the field. Trichoderma isolates and Tower 72 WP® recorded the highest tomato yields in the greenhouse. Selected microbial antagonists were effective in managing early blight in tomato under greenhouse and field conditions and minimised yield losses caused by the disease. These should be integrated in the management of early blight of tomatoes to reduce the dependence on agrochemicals.

In vitro and in vivo activity of essential oils extracted from Eucalyptus staigeriana, Eucalyptus globulus and Cinnamomum camphora against Alternaria solani Sorauer causing early blight in tomato

Early blight (EB) , caused by the fungus Alternaria solani, represents a serious problem in tomato production.This study aimed to evaluate the effectiveness of a synergistic strategy, combining phosphorus-solubilising bacteria PSB31 with ginger extract (GPE) in inhibiting early blight.The findings showed that strain PSB31 (identified as Bacillus sp.IMAU61039) presented the highest level of inhibition (46.9%) against the mycelial growth of A. solani, the causal agent of early blight in tomato plants.Among the treatments, the combination of PSB31 and GPE exhibited the most significant inhibitory effect on the mycelial growth (65.4%) of A. solani compared to the control.Moreover, under greenhouse conditions, tomato seeds treated with this combination showed the highest rate of early-blight inhibition (77.81%) compared to the untreated control (72.71%) and chemical disease control (90.23%).Notably, treatment of tomato seeds with the combination of PSB31 and GPE promoted seed germination (93.54%) and seedling development under A. solani infection.These results indicate the potential application of strain PSB31 in combination with GPE for controlling diseases caused by A. solani in tomato plants.

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.

Background: Early blight is a serious disease of tomato that reduces both yield and quality. Farmers often use chemical sprays to control it, but these can harm the environment and lose effectiveness over time. Using plant-based extracts is a natural and safer option to manage this problem. Objective: To evaluate the various phytochemical extracts for the management of early blight of tomato. Methdology: The antifungal efficacy of ten medicinal plants, namely; prickly acacia (Acacia nilotica L.), datura (Datura alba L.), black pepper (Piper nigrum L.), turmeric (Curcuma longa L.), garlic (Allium sativum L.), ginger (Zingiber officinale L.), oleander (Nerium oleander L.), eucalyptus (Eucalyptus globulus L.), ashwagandha (Withania somnifera L.), chinese date (Ziziphus mauritiana L.) along with the fungicide Mancozeb, were evaluated against Alternaria solani, the causal agent of tomato early blight, under in vitro and screen house conditions, and data was analyzed using the CRD model (ANOVA). Results: The In-vitro experiment with Potato Dextrose Agar (PDA) medium amended with 500 mg/L dose of the plant powder preparations, Mancozeb to be the most effective in reducing colony diameter of A. solani after 7-14 days of incubation. All the ten tested plants also reduced the colony diameter of A. solani significantly (p<0.05) as compared with unamended control. However, garlic, oleander and turmeric were found to be superior to the other plants. Similarly, these three plants, along with Mancozeb, also markedly reduced fungal biomass and spore concentration. In the screen house study (3000 mg/L), disease severity after the second application was lowest in Mancozeb-treated plants (16.7%), followed by garlic (26.6%), oleander (26.7%), and turmeric (30.0%), while the untreated control showed the highest severity (96.7%). Yield assessment revealed that during the first picking, maximum fruits per plant were obtained with Mancozeb (6.3), followed by garlic (5.3), oleander (4.7), and turmeric (4.7), whereas untreated, eucalyptus, and datura-treated plants produced the lowest (3.0 fruits each); a similar trend was recorded during the second picking. Furthermore, Mancozeb, garlic, oleander, and turmeric significantly improved plant growth attributes, including plant height, fresh weight, and dry weight, compared to untreated plants. Conclusions: It is concluded that garlic, oleander, and turmeric can be used as effective alternatives for managing early blight in tomato, with oleander being particularly promising due to its low cost and abundant availability.

Aqueous extracts of five plants with anti-microbial properties were evaluated for suppression of growth of Alternaria solani in laboratory conditions. At low concentration of 2%, four extracts including (Azadirachta indica) failed to suppress the growth. One extract ( Putranjiva roxburghii) showed significant suppression of pathogen growth at low concentration, according to Analysis of variance, Tukey’s post-test. Some extracts (Melia azedarach and Tabernaemontana divaricata ) on the contrary promoted the growth significantly more than the negative control. Discovery of a plant with better anti-fungal property than Azadirachta indica is a significant out-come of the investigation. Putranjiva roxburghii extract shows potential for management of an early blight of tomato in organic farming and for the isolation of bioactive molecule. Keywords: Plant extracts, anti-fungal, Alternaria, early blight, organic, tomato Cite this Article Heminder Singh, Gurpreet Kaur, Gurvarinder Kaur et al . Antifungal Potential of Plant Extracts against Alternaria solani, causing Early Blight of Tomato. Research & Reviews: Journal of Crop Science and Technology . 2018; 7(1): 22–26p.

Tomato (Solanum lycopersicum L.) is a globally vital horticultural crop, yet its productivity is severely threatened by early blight, caused by Alternaria solani. In a 2024 field survey across districts in Tamil Nadu, disease incidence ranged from 25.4% to 53.9% Per cent disease index, with the pathogen affects 60% in tomato field. Alternaria solani isolates were characterized morphologically, confirming typical septate, branched mycelia and muriform conidia. In vitro antifungal screening of eight newer-generation fungicides revealed that achieved the highest inhibition zone (48.15%), followed by difenoconazole at 42.73%, while hexaconazole exhibited the lowest activity (21.78%). These findings align with global studies demonstrating strobilurins’ superior efficacy in managing A. solani. The results suggest that azoxystrobin, either alone or in combination with triazoles, offers a promising tool for integrated early blight control in tomato cultivation. However, field trials, optimum dosing regimens, resistance monitoring, and integration with cultural practices are recommended to develop sustainable disease management strategies in tropical and subtropical regions.

BackgroundEarly blight (EB), caused by Alternaria solani, is one of the alarming diseases that restrict tomato production globally. Existing cultural practices and fungicide applications are not enough to control early blight diseases. Therefore, the study aimed to isolate, identify, and characterize an endophytic Streptomyces exhibiting the potential to control early blight in tomato and also promote plant growth.ResultsFrom a Citrus jambhiri leaf, an endophytic Streptomyces sp. with antagonistic activity against Alternaria solani, Colletotrichum acutatum, Cladosporium herbarum, Alternaria brassicicola, Alternaria sp., Fusarium oxysporum and Fusarium sp. was isolated. It was identified as a Streptomyces sp. through 16S ribosomal DNA sequence analysis and designated as SP5. It also produced indole acetic acid which was confirmed by Salkowski reagent assay, TLC and HPLC analysis. Treatment of pathogen infected plants with Streptomyces sp. SP5 antagonists (culture cells/culture supernatant/solvent extract/ acetone precipitates) decreased the early blight disease incidence and significantly increased the various agronomic traits.ConclusionThe present study concluded that Streptomyces sp. SP5 possessed antifungal activity against different fungal phytopathogens and had significant potential to control early blight disease and promote plant growth.

Piriformospora indica-primed transcriptional reprogramming induces defense response against early blight in tomato

Alternaria spp. form a heterogeneous group of saprophytic and plant-pathogenic fungi widespread in temperate and tropical regions. However, the relationship between evolutionary processes and genetic diversity with epidemics is unknown for several plant-pathogenic Alternaria spp. The interaction of Alternaria solani populations with potato and tomato plants is an interesting case study for addressing questions related to molecular evolution of an asexual fungus. Gene genealogies based on the coalescent process were used to infer evolutionary processes that shape the A. solani population. Sequences of the rDNA internal transcribed spacer (ITS) region and the genes which encode the allergenic protein alt a 1 (Alt a 1) and glyceraldehyde-3-phosphate dehydrogenase (Gpd) were used to estimate haplotype and nucleotide diversity as well as for the coalescent analyses. The highest number of parsimony informative sites (n = 14), nucleotide diversity (0.007), and the average number of nucleotide differences (3.20) were obtained for Alt a 1. Although the highest number of haplotypes (n = 7) was generated for ITS, haplotype diversity was the lowest (0.148) for this region. Recombination was not detected. Subdivision was inferred from populations associated with hosts but there was no evidence of geographic subdivision, and gene flow is occurring among subpopulations. In the analysis of the Alt a 1, balancing selection and population expansion or purifying selection could have occurred in A. solani subpopulations associated with potato and tomato plants, respectively. There is strong evidence that the subpopulation of A. solani that causes early blight in potato is genetically distinct from the subpopulation that causes early blight in tomato. The population of A. solani is clonal, and gene flow and mutation are the main evolutionary processes shaping its genetic structure.

This paper reports the in vitro and in vivo bioefficacy of a combination fungicide trifloxystrobin (25%) + tebuconazole (50%) against early blight disease of tomato (Lycopersicon esculentum Mill.) caused by Alternaria solani and their corresponding pre-harvest intervals (PHI) with reference to the maximum residue limits (European Union). Bioefficacy of the test fungicide combination revealed that in vitro conditions manifested the best control (75.1%) at 350 mg kg−1 against 76.2% control under field conditions. A sample preparation method based on ethyl acetate extraction and estimation by LC-MS multiple reaction monitoring (MRM) was validated in tomato fruits at 0.01 mg/kg and dissipation studies were conducted in field at single and double doses. The residues of both the compounds on all the sampling days were below the European Union maximum residue limits (EU-MRLs) and the maximum permissible intakes (MPIs) were calculated on the basis of prescribed acceptable daily intake (ADI). The combined bioefficacy and residue dynamics information will support label-claim of this fungicide combination for the management of early blight in tomato.