scholarly journals Management of Alternaria leaf blight in tomato plants by mentha essential oil

2020 ◽  
Vol 56 (No. 3) ◽  
pp. 191-196
Author(s):  
Kahkashan Perveen ◽  
Najat A. Bokhari

The essential oil obtained by the hydro-distillation of the leaves of Mentha arvensis Linnaeus was evaluated for its antifungal activity against the causal agent of the Alternaria blight of tomatoes, i.e., Alternaria alternata (Fries) Keissler. The antifungal activity of the mentha essential oil was assessed both in vitro and in vivo. The chemical composition of the mentha oil was also identified by GCMS analysis. The in vitro test revealed that the maximum inhibition in the mycelial growth (93.6%) and conidia germination (90.6%) was at the highest concentration (40 µL/mL), furthermore, it was found that the inhibition of the mycelial growth and conidia germination was dose dependent. The in vivo test proved that the application of the mentha essential oil (40 µL/mL) significantly increased the plant height (84.6%), fresh weight (81.5%) and dry weight (80.0%) when compared to the untreated tomato plants. The disease incidence was 3.5 in the untreated plants, while it was 0.93 for the mentha essential oil treated plants and was 0.08 in the carbendazim treated plants. The GC-MS analysis of the mentha essential oil identified 18 compounds in total, among which the percentage of menthol was the highest (69.2%). The mentha essential oil was successful in managing the Alternaria leaf blight in the tomato plants. Therefore, it can be explored further for the development of a natural fungicide.

Author(s):  
Flávia Mota de Figuerêdo Alves ◽  
Kevison Romulo da Silva França ◽  
Ionaly Gomes de Araújo ◽  
Lídia Pinheiro da Nóbrega ◽  
Alda Leaby dos Santos Xavier ◽  
...  

Aims: This study aimed to evaluate the fungitoxic potential of melaleuca essential oil on the mycelial growth of Alternaria alternata under in vitro condition and the treatment of cowpea beans. Study Design: The experiments comprised completely randomized designs: Eleven treatments with five replicates on in vitro test; and six treatments with five replicates on in vivo test. Place and Duration of Study: The work was carried out at the Center for Agrifood Science and Technology of the Federal University of Campina Grande, Pombal, Brazil, since February 2018 to February 2019. Methodology: In the in vitro experiment, the essential oil was incorporated into the culture medium and poured into Petri dishes. The treatments consisted of different concentrations of the essential oil (0.0125, 0.025, 0.05, 0.1, 0.2, 0.25, 0.50, 0.75, and 1.0%), a negative control (0.0%), and a positive control (Thiram). Discs of culture medium with fungal mycelia were inoculated in the center of the plates and incubated for seven days at 27±2ºC. The percentage of mycelial growth inhibition (PGI) and the index of mycelial growth speed (IMGS) was calculated to verify the difference between treatments. In the in vivo experiment, the bean seeds were treated with different concentrations of EO (0.0, 0.2, 0.5, 1.0, and 5.0%), a negative control (0.0%), and positive control (Thiram). Seeds were inoculated with colonies of the fungus for 48 hours, and after that, we performed the seed sanity test. Results: Under in vitro conditions, all concentrations of melaleuca essential oil reduced the mycelial growth of A. alternata. The oil reached complete inhibition of fungal growth from 0.2% concentration and above. In the cowpea treatment, the essential oil had no significant control over the percentage of infected seeds. Conclusion: The melaleuca essential oil had a fungitoxic effect on the A. alternata under in vitro conditions. However, using the adopted methodology, on the cowpea bean seed treatment, the essential oil did not reduce the incidence of A. alternata.


Author(s):  
Tiago Silva Lima ◽  
Kevison Romulo da Silva França ◽  
Plinio Tércio Medeiros de Azevedo ◽  
Yaroslávia Ferreira Paiva ◽  
José Carlos Santos Silva ◽  
...  

Aims: This study evaluates the inhibitory potential of the clove essential oil (Syzygium aromaticum L.) on phytopathogenic fungi in vitro and on maize seeds. Study Design: The experiments comprised completely randomized designs: Seven treatments with five replicates on in vitro test; and four treatments with five replicates each, on in vivo test. Place and Duration of Study: The work was carried out at the Center for Agrifood Science and Technology of the Federal University of Campina Grande, Pombal, Brazil, from April to May 2018. Methodology: In the in vitro test, the essential oil was incorporated into the PDA (Potato-Dextrose-Agar) culture medium. The treatments comprised five concentrations of the oil (0.0125, 0.025, 0.05, 0.1, and 0.2%), a negative control (0.0%), and a positive control (Tiram). Plates were inoculated with the tested fungi, Fusarium verticillioides, Macrophomina phaseolina, and Macrophomina pseudophaseolina, then incubated for seven days at 27±2°C. The percentage of mycelial growth inhibition (PGI) and mycelial growth rate index (MGRI) were estimated. In the in vivo test, maize seeds (AG1051 hybrid) were treated with the essential oil on concentrations equal or superior to the minimum inhibitory concentration found in the in vitro test, besides the negative and positive controls. The artificial inoculation was carried out in fungi colonies for 32 hours and the seed sanity test was performed. The percentage of seeds infected by the fungus was evaluated after seven days. Results: In vitro conditions, clove oil totally inhibited the mycelial growth of F. verticillioides, M. phaseolina and M. pseudophaseolina at concentrations of 0.05, 0.1 and 0.1%, respectively. At 0.2% concentration significantly reduced the incidence of colonies of fungi M. phaseolina and M. pseudophaseolina in hybrid corn seeds AG 1051. Conclusion: The clove essential oil had a fungitoxic effect on the phytopathogens evaluated, under in vitro and in the treatment of maize seeds.


Author(s):  
Kevison Romulo da Silva França ◽  
Flavia Mota de Figueredo Alves ◽  
Tiago Silva Lima ◽  
Alda Leaby dos Santos Xavier ◽  
Plínio Tércio Medeiros de Azevedo ◽  
...  

This study evaluates the in vitro effects of Lippia gracilis essential oil on the mycelial growth of phytopathogenic fungi. Experiments were carried out using a completely randomized design to assess the effects of eight treatments. Five replicates were evaluated for each experimental group. The essential oil was incorporated into the potato dextrose culture medium and poured into Petri dishes. Treatments were comprised of different concentrations of the oil (0.0125, 0.025, 0.05, 0.1, and 0.2%), a negative control (0.0%), and two positive controls (commercial fungicides). The plates were inoculated with fungi including Colletotrichum gloeosporioides, C. musae, C. fructicola, C. asianum, Alternaria alternata, A. brassicicola, Fusarium solani, F. oxysporum f. sp. cubense, and Lasiodiplodia theobromae and were incubated for seven days at 27 ± 2°C. The following variables were measured to verify the differences observed among treatments: percentage of mycelial growth inhibition and index of mycelial growth speed. All concentrations of L. gracilis oil inhibited the mycelial growth of the fungal species evaluated. The complete inhibition was observed between concentrations of 0.0125 and 0.1%. Treatment with oil inhibited fungal growth with similar, or even greater, efficiency than commercial fungicides.. We recommend the development of in vivo tests to verify whether L. gracilis essential oil can protect against fungal disease in live plants.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9626
Author(s):  
Huiyu Hou ◽  
Xueying Zhang ◽  
Te Zhao ◽  
Lin Zhou

Background Botrytis cinerea causes serious gray mold disease in many plants. This pathogen has developed resistance to many fungicides. Thus, it has become necessary to look for new safe yet effective compounds against B. cinerea. Methods Essential oils (EOs) from 17 plant species were assayed against B. cinerea, of which Origanum vulgare essential oil (OVEO) showed strong antifungal activity, and accordingly its main components were detected by GC/MS. Further study was conducted on the effects of OVEO, carvacrol and thymol in vitro on mycelium growth and spore germination, mycelium morphology, leakages of cytoplasmic contents, mitochondrial injury and accumulation of reactive oxygen species (ROS) of B. cinerea. The control efficacies of OVEO, carvacrol and thymol on tomato gray mold were evaluated in vivo. Results Of all the 17 plant EOs tested, Cinnamomum cassia, Litsea cubeba var. formosana and O. vulgare EOs had the best inhibitory effect on B. cinerea, with 0.5 mg/mL completely inhibiting the mycelium growth of B. cinerea. Twenty-one different compounds of OVEO were identified by gas chromatography–mass spectrometry, and the main chemical components were carvacrol (89.98%), β-caryophyllene (3.34%), thymol (2.39%), α-humulene (1.38%) and 1-methyl-2-propan-2-ylbenzene isopropyl benzene (1.36%). In vitro experiment showed EC50 values of OVEO, carvacrol and thymol were 140.04, 9.09 and 21.32 μg/mL, respectively. Carvacrol and thymol completely inhibited the spore germination of B. cinerea at the concentration of 300 μg/mL while the inhibition rate of OVEO was 80.03%. EC50 of carvacrol and thymol have significantly (P < 0.05) reduced the fresh and dry weight of mycelia. The collapse and damage on B. cinerea mycelia treated with 40 μg/mL of carvacrol and thymol was examined by scanning electron microscope (SEM). Through extracellular conductivity test and fluorescence microscope observation, it was found that carvacrol and thymol led to increase the permeability of target cells, the destruction of mitochondrial membrane and ROS accumulation. In vivo conditions, 1000 μg/mL carvacrol had the best protective and therapeutic effects on tomato gray mold (77.98% and 28.04%, respectively), and the protective effect was significantly higher than that of 400 μg/mL pyrimethanil (43.15%). While the therapeutic and protective effects of 1,000 μg/mL OVEO and thymol were comparable to chemical control. Conclusions OVEO showed moderate antifungal activity, whereas its main components carvacrol and thymol have great application potential as natural fungicides or lead compounds for commercial fungicides in preventing and controlling plant diseases caused by B. cinerea.


2020 ◽  
pp. 1379-1384
Author(s):  
Alex Rodrigues Silva Caetano ◽  
Sara Maria Chalfoun ◽  
Mario Lúcio Vilela Resende ◽  
Caroline Lima Angélico ◽  
Wilder Douglas Santiago ◽  
...  

Essential oils, also known as volatile oils, are substances produced through the secondary metabolism of plants. In this study, we determined the chemical composition and the in vitro and in vivo antifungal activity of the essential oils from four species of Eucalyptus, Eucalyptus citriodora, Eucalyptus camaldulensis, Eucalyptus grandis and Eucalyptus microcorys, against the Hemileia vastatrix fungus. The essential oils from these four species of Eucalyptus were extracted from their leaves by the hydrodistillation technique using a modified Clevenger apparatus. The chemical characterization was performed by gas chromatography coupled with a mass spectrometer detector and by gas chromatography using a flame ionization detector. The antifungal activities of the essential oils against H. vastatrix were studied by evaluating the percentage of spore germination using the microdilution test for in vitro assays. The curative and preventive effects were evaluated in in vivo tests. The principal constituents of the essential oil from E. citriodora were citronellal, citronellol and isopulegol, while E. camaldulensis produced 1,8-cineole, α-terpineol and α-pinene. 1,8-cineole, α-pinene and α-terpineol were obtained from E. grandis and 1,8-cineole, α-pinene and trans-pinocarveol were the principal components in the essential oil of E. microcorys. In vitro and in vivo antifungal activities against the fungus under study were observed for most of the essential oils, except the essential oil from E. microcorys, for which no preventive antifungal activity was observed. Only the curing of infection by the H. vastatrix fungus was observed with this oil.


2016 ◽  
Vol 46 (1) ◽  
pp. 2-15 ◽  
Author(s):  
Dawa Dolma Bhutia ◽  
Yeka Zhimo ◽  
Ramen Kole ◽  
Jayanta Saha

Purpose – The purpose of this paper was to determine the antifungal activities of different solvent extracts of common plants in vitro and in vivo against banana anthracnose fungus Colletotrichum musae (Berk & M.A. Curtis) Arx, and to investigate its effects on the pathogen and identify the bio active component(s). Design/methodology/approach – Extracts were obtained from leaves, tender shoots, rhizomes, bulbs, seeds and fruits of 42 naturally growing plant species following hot sequential extraction. Preliminary screening of the solvent extracts was done based on the inhibition of radial mycelial growth of C. musae following poison food technique and conidial germination inhibition by cavity slide technique. The selected extracts were assessed for their effect on harvested banana in reducing anthracnose during storage. The active components in the bio-active fractions of plant extract were identified by gas chromatography-mass spectroscopy. Findings – Methanol extracted a larger quantity of material (between 6.9 and 12.5 per cent) than hexane or chloroform, and all its extracts were active against the test pathogen with mycelial growth inhibition ranging from 13.70 to 88.89 per cent. Zingiber officinale rhizome extract as well as Polyalthia longifolia and Clerodendrum inerme leaf extracts exhibited more than 80 per cent inhibition of mycelial growth. Total inhibition of spore germination of C. musae was recorded in Z. officinale and P. longifolia extracts at 0.3 per cent w/v and 0.5 per cent w/v concentration, respectively, while only 68 per cent spore inhibition was recorded in C. inerme at 0.5 per cent w/v concentration. Of the three plant species, Z. officinale had the best antifungal activity (18.0 per cent disease incidence; 2.2 disease severity scale) when banana fruits were dipped in the extract at a concentration of 0.5 per cent w/v at 5 days of storage in ambient condition (80-82 per cent R.H., 27 ± 1°C). The bio-active compounds in the extract of Z. officinale were identified as alpha-curcumene and zingerone. Originality/value – Based on the antifungal activity, plant extract of Z. officinale can be used as an effective alternative to chemicals in controlling anthracnose pathogen in harvested banana.


2018 ◽  
Vol 48 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Andréa Mirne de Macêdo Dantas ◽  
Selma Rogéria de Carvalho Nascimento ◽  
Beatriz Letícia Silva da Cruz ◽  
Fernando Henrique Alves da Silva ◽  
Márcia Michelle de Queiroz Ambrósio ◽  
...  

ABSTRACT Controlling post-harvest papaya diseases without using agrochemicals is a challenge for producers. This study aimed at evaluating the effect of clove essential oil, biological fungicide (Trichodermil®), resistance inducer (Cob Sistem®) and chemical fungicide (Imazacure®) on the in vitro control of phytopathogenic fungi isolates from papaya as well as on the post-harvest quality of Tainung 1 papaya. The in vitro experiment was conducted in a complete randomized design, with five fungal species x five treatments and five replications. The in vivo experiment was conducted in a complete randomized design, with five treatments x five storage times, five replications and three fruits per replication. The fruits were stored under refrigeration at 10 ± 2 ºC and 90 ± 5 % of relative humidity and evaluated at 0, 7, 14, 21 and 28 days of storage, plus two shelf life days at 25 ± 2 ºC, to simulate marketing conditions. The inhibition of mycelial growth was evaluated in the in vitro experiment, while the diseases occurrence and post-harvest quality of the fruits were evaluated in the in vivo experiment. The clove essential oil and Trichodermil® were as efficient as Imazacure® in inhibiting the mycelial growth of Alternaria sp., Colletotrichum gloeosporioides and Rhizopus sp. The treatments with clove essential oil, Trichodermil® and Imazacure® were similar in controlling the pathogens up to 21 days of storage. The treatments had no effect on the fruits soluble solid contents.


Author(s):  
Léon W. Nitiema ◽  
Fabrice W. Nikiema ◽  
Drissa Sérémé ◽  
Pierre A. E. D. Sombié

Aims: This study was undertaken to investigate the antifungal activities of Securidaca longepedunculata and Acacia gourmaensis bark hydro-ethanolic extract against Fusarium solani, Fusarium moniliforme and Curvularia lunata and to evaluate the percentages of germination and infection of infected rice seeds. Methods: Different extract concentrations ranging from 0.25, 0.5 and 1% were tested during 15 days using poisoned food technique method for in vitro antifungal activity against above three fungal strains. The same concentrations of extract were used to evaluate in vivo antifungal activity on rice seeds infected by these three fungal strains. Results: The extract of Securidaca longepedunculata had antifungal effect on Fusarium solani and Fusarium moniliforme and completely inhibited its mycelial growth at all tested concentrations (0.25, 0.5 and 1%). Curvularia lunata mycelial growth was inhibited of 84.7% by 1% Securidaca longepedunculata extract after five days of culture. However, mycelial growth of F. solani, F. moniliforme and C. lunata were increased with increasing concentration of Acacia gourmaensis extract. It has been observed that when Securidaca longepedunculata hydro-ethanolic extract concentration increased up to 1%, seeds germination percentage decreased for all infection. In contrast, the opposite was observed for Acacia gourmaensis extract. Likewise, seeds infection decreased with the highest concentration (1%) of Securidaca longepedunculata for all infection, whereas the opposite was observed with Acacia gourmaensis extract. Conclusion: This study showed that S. longepedunculata hydro-ethanolic extract has more antifungal activity against seed-borne fungi (F. solani, F. moniliforme and C. lunata) than A. gourmaensis in vitro and in vivo. Results show that Securidaca longepedunculata hydro-ethanolic bark extract can be used as a potential antifungal agent in the management of some rice fungal diseases. Acacia gourmaensis extract, at low concentration, could be used in rice seed treatment to increase seed germination.


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