Tomato Early Blight Research Articles

Evaluating the Antifungal Activity of Some Traditional Medicinal Plant Extracts against Alternaria solani (Tomato Early Blight Pathogen) in Ethiopia

Background: Tomato (Lycopersicon esculentum Mill.) belongs to the family Solanaceae. In Ethiopia, control of early blight is largely dependent on fungicidal application. There is a research need to identify effective botanical extracts to control Alternaria solani that cause early blight of tomato and for evaluation of plant extracts through different solvents on the target pathogen. Methods: In vitro experiment was conducted to evaluate the effectiveness of crude extracts of 16 selected medicinal plants against Alternaria solani. Thus, crude extracts were extracted from medicinal plants with different solvents (methanol, ethanol and petroleum at (25%, 50% and 100%) concentrations. The Alternaria solani was isolated from infected tomato leaves showing early blight symptoms. Evaluation of plant extracts was carried out against Alternaria solani using food poisoned technique on PDA. Result: Results showed that most of the methanolic extract plants were showed significant inhibition of the mycelial growth as compared to ethanolic and petroleum ether extracts. A higher rate of mycelial reduction was recorded by ethanol extracts of Allium sativum at all concentrations (100%) followed by methanol extracts of Allium sativum at 25%, 50%, 100% concentration (90.02%, 97.01%, 100% respectively). The effectiveness of extracts against Alternaria solani depends on use at the higher concentrations and various solvents. For crude extracts that have shown higher inhibitory effects against Alternaria solani in vitro conditions, actual chemical compounds should be identified. Furthermore, it is also important to evaluate these plants on other microbes, study to test in vivo and to assess their real potential field condition wherever early blight is an important disease of tomato.

Indirect Effect of Some Insecticides on Tomato Early Blight (Alternaria solani) Under Laboratory and Greenhouse Conditions

Matrood, A.A.A., A. Rhouma and A.H.F. Al-Taie. 2022. Indirect Effect of Some Insecticides on Tomato Early Blight (Alternaria solani) Under Laboratory and Greenhouse Conditions. Arab Journal of Plant Protection, 40(3): 231-239. https://doi.org/10.22268/AJPP-40.3.231239 Early blight disease is one of the serious diseases of tomato caused by Alternaria solani. In some instances, annual economic yield loss due to this disease was estimated at 80%. Currently, pesticide applications are used for the management of early blight disease due to the lack of resistant cultivars. The effect of treatment of the susceptible tomato cultivar Super Marmond with three insecticides (Diazinon, Match® 050 EC and Vertimec®) was evaluated under laboratory and greenhouse conditions. In vitro assay showed that the pesticide Vertimec® (at a concentration of 300 ppm) was the most effective against A. solani with mycelial growth inhibition above 93%, inhibition of fungal sporulation to 0.26x103 spores/ml, and spore germination inhibition of 98.79%. In addition, there was a reduction in A. solani spores and their dry weight (0.0144 mg) in the presence of Vertimec®. In greenhouse experiments, when Vertimec® was used curatively on tomato leaves against A. solani, it lowered significantly disease severity (20.33%). The effect of this insecticide was not limited only to the protection of tomato plants but it also improved their growth by increasing the tomato shoot fresh and dry weights (21.94 g and 3.85 g, respectively) as well as the root fresh and dry weight (3.84 g and 0.89 g, respectively). Based on the results obtained, it can be concluded that Vertimec® could be used for early blight management when the tomato crop is also infested with insect pests. Keywords: Alternaria solani, early blight, insecticide, tomato.

Effects of depth levels of burial on the survival of Alternaria solani causing early blight of tomato

Effects of depth levels of burial on the survival of Alternaria solani causing early blight of tomato

Ganoderma lucidum as a Biocontrol agent for Management of Alternaria solani, A Pathogen of Early Blight of Tomato

Ganoderma lucidum as a Biocontrol agent for Management of Alternaria solani, A Pathogen of Early Blight of Tomato

Prevalence of tomato early blight disease in Tamilnadu and morpho-cultural characterization of Alternaria solani isolates

The present study was conducted with an objective to assess the prevalence and incidence of tomato early blight disease at different locations in five districts of Tamilnadu, India during 2016. The growth characters and pathogenic variability among the isolates of Alternaria solani were recorded. The survey revealed that the per cent disease index ranged from 12.52 to 34.72 per cent among five tomato growing districts. Amongst the collected isolates AS5 showed maximum radial growth (88.56mm), conidial size (265.63µm x 23.28µm) and beak length (147.71µm). The same isolate was also found as most aggressive with maximum per cent disease incidence (69.46%) on artificial inoculation. The pigmentation, sporulation, growth margin and zonation were also found to vary amongst different isolates. AS5 was found most aggressive with maximum per cent disease index (69.46%) followed by AS2, AS9 and AS6 with a PDI of 65.42, 56.74 and 52.41 per cent, respectively. The least PDI (24.38%) was recorded with isolate AS8.

Identify the Source of Resistant Against Early Blight of tomato Caused by Alternaria solani

Identify the Source of Resistant Against Early Blight of tomato Caused by Alternaria solani

Impact of different media, temperature and pH on the growth of Alternaria solani causing tomato early blight disease

Studies on the impact of different media, influence of temperature and pH on the growth, cultural and morphological characters of pathogen is greatly influenced for successful management of crop diseases. Therefore, the present study was carried out during 2017 at the Department of Plant Pathology, Faculty of Agriculture, Annamalai University, Tamil Nadu, India to assess the growth of Alternaria solani in different media, temperature and pH. A. solani was inoculated with different media, range of temperature and pH and assess their growth by agar plate method. All the experiments replicated thrice. The study clearly revealed that among the media tested both solid and liquid, PDA and PD broth was found to be the best in supporting the mycelial growth (88.67mm) and mycelial dry weight (289.51mg) of the pathogen. Also, the study proved that temperature of 30ºC was suitable for A. solani and recorded maximum mycelial growth of 69.52mm. Whereas, the optimum pH for the growth of pathogen 6.5 and recorded maximum mycelial growth of 71.52mm. It is concluded that the isolate will be further tested for their aggressiveness in early blight disease incidence.

English

The current research was conducted to investigate the alterations in the mineral status in the leaves of tomato plants against early blight (EB) caused by Alternaria solani. Six tomato varieties; viz. Riograndae, Roma and Basket (resistant) and T-88572, BHN-961 and BHN-1021(susceptible) were inoculated with a blend of five isolates of Alternaria solani, collected from different regions of Faisalabad District. These six varieties for mineral profiling were selected after two years screening from twenty-five varieties of tomatoes under field conditions. These varieties were sown in pots and artificial inoculation was performed to develop disease in inoculated type of tomato plants while distilled water was applied on un-inoculated type of plants. Newly infected leaves from upper, middle and lower parts of tomato plants from resistant and susceptible groups were used to prepare sample for mineral analysis at p ≤ 0.05 and variation in mineral profiling of resistant and susceptible groups of tomato plants was determined through Nested Structured Design. Significant variation was observed in inoculated (3.12, 0.48 %, 1.17, 0.14, 0.42, 0.21, 0.69 and 1.49 ppm and un-inoculated type (8.67, 1.61%, 10.45, 0.22, 1.75, 1.98, 3.09 and 3.39 ppm) while resistant group expressed 6.59, 1.19%, 8.13, 1.973, 1.69, 1.26, 1.36, 2.43 and 2.87ppm and susceptible group exhibited 5.19, 0.91%, 5.69, 1.693, 1.24, 0.91,0.83, 1.35 and 2.22 ppm with respect to NPK, Ca, Mg, Na, Zn, Iron and copper. Resistant variety, Riograndae expressed maximum amount while T-88572 exhibited minimum amount of all mineral contents. Alterations in the mineral profiling in leaves of tomato plants can be used by researchers as biochemical markers for identification and development of resistant source against early blight of tomato and for the development of ecofriendly management strategy towards A. solani.

Benzoic Acid and Its Hydroxylated Derivatives Suppress Early Blight of Tomato (Alternaria solani) via the Induction of Salicylic Acid Biosynthesis and Enzymatic and Nonenzymatic Antioxidant Defense Machinery.

Tomato early blight, caused by Alternaria solani, is a destructive foliar fungal disease. Herein, the potential defensive roles of benzoic acid (BA) and two of its hydroxylated derivatives, ρ-hydroxybenzoic acid (HBA), and protocatechuic acid (PCA) against A. solani were investigated. All tested compounds showed strong dose-dependent fungistatic activity against A. solani and significantly reduced the disease development. Benzoic acid, and its hydroxylated derivatives, enhanced vegetative growth and yield traits. Moreover, BA and its derivatives induce the activation of enzymatic (POX, PPO, CAT, SlAPXs, and SlSODs) and non-enzymatic (phenolics, flavonoids, and carotenoids) antioxidant defense machinery to maintain reactive oxygen species (ROS) homeostasis within infected leaves. Additionally, BA and its hydroxylated derivatives induce the accumulation of salicylic acid (SA) and its biosynthetic genes including isochorismate synthase (SlICS), aldehyde oxidases (SlAO1 and SlAO2), and phenylalanine ammonia-lyases (SlPAL1, SlPAL2, SlPAL3, SlPAL5, and SlPAL6). Higher SA levels were associated with upregulation of pathogenesis-related proteins (SlPR-1, SlPR1a2, SlPRB1-2, SlPR4, SlPR5, SlPR6), nonexpressor of pathogenesis-related protein 1 (SlNPR1), and salicylic acid-binding protein (SlSABP2). These findings outline the potential application of BA and its hydroxylated derivatives as a sustainable alternative control strategy for early blight disease and also deciphering the physiological and biochemical mechanisms behind their protective role.

Endophytic fungus Acrophialophora jodhpurensis induced resistance against tomato early blight via interplay of reactive oxygen species, iron and antioxidants

In this study, potential of the endophytic fungus Acrophialophora jodhpurensis in induction of tomato resistance against Alternaria alternata the causal agent of early blight disease, was investigated. The obtained results revealed that colonization of tomato roots by A. jodhpurensis reduced progress of the disease caused by A. alternata on the leaves. Activity of antioxidant enzymes, phenolic contents, lignin accumulation, relative water content, cell membrane stability, accumulations of superoxide (O2-) and hydrogen peroxide (H2O2) increased, also iron ions and cell death reduced in the plants inoculated with A. jodhpurensis prior to the pathogen infection. Therefore, the beneficial root colonizing fungus A. jodhpurensis might be an appropriate candidate for plant protection against A. Alternata via induction of systemic resistance in the plant tissues, which is related to activation of various defense mechanisms.

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

One of the main leaf diseases of tomato is the early blight, caused by the fungus Alternaria solani. The use of essential oils could be an alternative for controlling by acting plant defense against phytopathogens. The objective was to evaluate the antifungal, the early blight control, and the activity of defense enzymes in tomato treated with tea tree (Melaleuca alternifolia) essential oil. Aiming to evaluate the mycelial growth and sporulation of the pathogen, mycelial discs were placed in Petri dishes with 0, 500, 1000, 1500, 2000, and 2500 μL L−1 of essential oil, and an additional treatment with fungicide (azoxystrobin + diphenoconazole). The treatments were applied onto the second pair of leaves of tomato plants grown in a greenhouse, and after three days the pathogen was inoculated in the second and third pairs of leaves. Severity was expressed through the area under the disease progress curve (AUDPC). The peroxidase, polyphenoloxidase and phenylalanine ammonia-lyase activities were evaluated with the concentration of 1500 μL L−1. Mycelial growth showed a linear decrease as concentrations increased. In the treated leaves, the 1500 μL L−1 concentration showed the most reduction in AUDPC, corresponding to 53%, whereas in the untreated leaves, the most effective concentration was 2000 μL L−1 with 42% inhibition. An increase in peroxidase and phenylalanine ammonia-lyase activities were observed in the tomato leaves. Tea tree essential oil can be an alternative for the control of early blight in tomato.

Effectiveness of some biotic and abiotic agents to control tomato early blight disease caused by Alternaria solani

Bacillus megaterium, Bacillus subtilis, Pseudomonas fluorescens, Trichoderma harzianum, Trichoderma album and Trichoderma viride isolates, as well as different concentrations of chemical inducers, such as chitosan and salicylic acid were evaluated against Tomato early blight, under laboratory and greenhouse conditions. Under laboratory conditions, all tested bio agents, as well as the different concentrations of the tested chemical inducers, decreased the linear growth of A. solani, as the inhibition of fungal growth was increased by increasing the concentration of both chemical inducers in the growing medium. The chemical inducer chitosan at a concentration of 4.0 mg/mL PDA medium, caused the highest inhibition of linear growth of the fungus, followed by anti-fungus T. harzianum. When, different concentrations of chitosan and salicylic acid were tested on spore germination of A. solani, a concentration of 4.0 (mg/mL), for chitosan and a concentration of 25.0 (mM), for salicylic acid were the best concentrations used to reduce the spore germination of A. solani. Under greenhouse conditions, spraying tomato plants (cv. Super Strain B hybrid), with any of the tested biological agents as well as different concentrations of both the chemical inducers before infection of tomato plants by A. solani reduced the severity of early blight, in addition, to increase the fresh and dry weight of tomato plants. The chemical inducer chitosan at a concentration of 4.0 (mg/mL), caused the highest decrease of the disease severity, and the highest increase in fresh and dry weight of tomato plants, followed by the bio agent T. harzianum. The activities of defense-related enzymes i.e., polyphenoloxidase, peroxidase and chitinase were significantly increased in all treated plants with the tested biotic and abiotic agents. Chitosan at a concentration of 4.0 (mg/mL) resulted in the highest activity of oxidative enzymes, followed by T. harzianum. Meanwhile, the total content of phenols was higher in treated plants than in the untreated ones. The tested bio agents and chemical inducers might be playing an important role in management of tomato early blight through induction of induced systemic resistance.

Efficacy of some conventional fungicides and essential oils against tomato early blight disease

Fungicidal activity of nine selected conventional fungicides, identified five plant oils and their combined effect against A. solani, the causal pathogen of early blight on tomato. GC-MS analysis of the tested oils indicated that terpene hydrocarbons (97%) with cinnamaldehyde as the major compound; sulfur compounds; fatty acids and organo-sulfur-containing compounds were the main components in cinnamon, garlic, mustard and onion oils, respectively. In vitro, Speedcide® (difenoconazole) and Cabrioduo® (Dimethomorph + Pyraclostrobin) were the most effective against the A. solani fungus with EC50 values of 94.6 and 88.6 ppm respectively. Toledo® (Tebuconzole) achieved EC50 value of 631.2 ppm. Roxyl-M® was significantly more effective than Roxyl–plus® or Remik®. Speedcide® alone or mixed with mandipropamid or azoxystrobin in Revus-Top® or Cruze® were the lowest effective in vitro. Garlic and mustard oils were more effective in liquid media than solid one. Cinnamon, onion, garlic and bitter almond oils caused moderate fungi-toxicity against early blight pathogen and could be implemented in the IPM program. Lower EC50 values were obtained in case of combinations of fungicides with oils than separate treatments. Effect of the active conventional fungicides and plant oils on disease indices, relative disease control, chlorophyll content, sugar contents and poly phenol oxidase in tomato plants was also studied.

Efficacy of some conventional fungicides and essential oils against tomato early blight disease

Efficacy of some conventional fungicides and essential oils against tomato early blight disease

INFLUENCE OF VARIOUS MEDIA AND NUTRIENT SOURCES ON ALTERNARIA SOLANI CAUSE EARLY BLIGHT DISEASE IN TOMATO

Early blight of tomato (Solanum lycopersicum L.) incited by Alternaria solani is highly destructive causing yield loss up to 78 per cent. The fungus was tested with different media along with the host extract and different nutrient sources for their growth and development in in vitro. Twelve different media were tested on the growth of A. solani, among them potato dextrose agar + host leaf extract recorded maximum radial mycelial growth of A. solani (89.57mm) and potato dextrose broth + leaf extract has maximum mycelial dry weight (613mg). Six carbon and nitrogen sources amended media were tested. Among carbon sources, glucose recorded maximum radial mycelial growth (74.65mm) and mycelia dry weight (709.17mg). Among the nitrogen sources, ammonium nitrate has the enhanced the radial mycelail growth (84.56 mm) and high mycelial dry weigh (654.27mg). This study will be helpful for further investigations on the physiology of the fungus and management of the disease.

Lanthanum in vitro control of Alternaria solani and induction resistance mechanism against blight tomato plant

Rare earth elements have been tested in control of plant diseases. Lanthanum (La) was tested in the control of Alternaria solani (in vitro) and tomato early blight (in vivo) using the concentration 0; 0.1; 0.2; 0.4 and 0.8 g L-1. In vitro, the concentration were diluted in V8 culture medium and evaluated for mycelial growth rate index (MGRI) and pathogen sporulation. In vivo, 24 hours after the application of concentration was inoculate the pathogen and 24 hours after the inoculation, leaflets were collected for quantification, the specific catalytic activity and guaiacol peroxidase. The severity of tomato early blight were also analyzed. As 0.27 and 0.28 g L-1 reduces 28% and 50% the MGRI and the sporulation, respectively. Peroxidase and catalase activity was increased by 298% and 151% in tomato treated with 0.5 and 0.4 g L-1de La, respectively. In vivo reduces AUDPC 70% when was applied 0.27 g L-1 La. Lanthanum can be used as resistance inducer in controlling tomato early blight.

Role of biochar, compost and plant growth promoting rhizobacteria in the management of tomato early blight disease

The individual role of biochar, compost and PGPR has been widely studied in increasing the productivity of plants by inducing resistance against phyto-pathogens. However, the knowledge on combined effect of biochar and PGPR on plant health and management of foliar pathogens is still at juvenile stage. The effect of green waste biochar (GWB) and wood biochar (WB), together with compost (Comp) and plant growth promoting rhizobacteria (PGPR; Bacillus subtilis) was examined on tomato (Solanum lycopersicum L.) physiology and Alternaria solani development both in vivo and in vitro. Tomato plants were raised in potting mixture modified with only compost (Comp) at application rate of 20% (v/v), and along with WB and GWB at application rate of 3 and 6% (v/v), each separately, in combination with or without B. subtilis. In comparison with WB amended soil substrate, percentage disease index was significantly reduced in GWB amended treatments (Comp + 6%GWB and Comp + 3%GWB; 48.21 and 35.6%, respectively). Whereas, in the presence of B. subtilis disease suppression was also maximum (up to 80%) in the substrate containing GWB. Tomato plant growth and physiological parameters were significantly higher in treatment containing GWB (6%) alone as well as in combination with PGPR. Alternaria solani mycelial growth inhibition was less than 50% in comp, WB and GWB amended growth media, whereas B. subtilis induced maximum inhibition (55.75%). Conclusively, the variable impact of WB, GWB and subsequently their concentrations in the soil substrate was evident on early blight development and plant physiology. To our knowledge, this is the first report implying biochar in synergism with PGPR to hinder the early blight development in tomatoes.

Potential of Trichoderma spp., Bacillus subtilis and Pseudomonas fluorescens in the management of early blight in tomato

ABSTRACT 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.

Curvularia lunata as new causal pathogen of tomato early blight disease in Egypt.

Tomato plants displaying early blight symptoms were collected from different localities in the provinces of Assiut and Sohag, Egypt. The causal pathogens were isolated on potato dextrose agar plates. Pathogenicity tests with 48 isolates were carried out under greenhouse conditions on tomato cultivar (CV 844). All tested isolates caused symptoms of early blight disease with different degrees. The highest disease severity on tomato plants was found after inoculation with isolate No. 6 followed by isolates No. 20 and No. 31. The most pathogenic isolates were identified by sequence analysis using ITS1 and ITS4 primers. The analysis of the amplified sequences from fungal isolates No. 6, 20 and 31 displayed 99-100% nucleotide identity with Alternaria solani, Curvularia lunata and A. alternata, respectively. To our knowledge, this is the first report of Curvularia lunata as one of the causal pathogens of early blight disease of tomato plants in Egypt.

Pathological Survey on Early Leaf Blight of Tomato and In Vitro Effect of Culture Media, Temperature and pH on Growth and Sporulation of Alternaria solani

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.