Browsing by Author "Daranagama, D."

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Biocontrol potential of endophytic fungi in tea (Camellia sinensis (L.) Kuntze) leaves against selected fungal phytopathogens
(Malaysian Journal of Microbiology, 2022) Thambugala, K.; Daranagama, D.; Kannangara, S.
Aims: Endophytic fungi are a diverse group of microorganisms that stay asymptomatically in the healthy tissues of the host. Many fungal endophytes are associated with the tea plant (Camellia sinensis) and the pathogens of the tea plant have the potential to grow as endophytes or act as latent pathogens during the initial growth of the plant. The present study aimed at screening tea endophytic fungi with the potential for control of a few critical phytopathogens, Fusarium sp., Lasiodiplodia theobromae, Pestalotiopsis sp. and Sclerotinia sclerotiorum while evaluating the efficiency of growth inhibition of these phytopathogens by the endophytic fungal isolates using in vitro assays. Methodology and results: Five endophytic fungal strains; Colletotrichum gloeosporioides, C. siamense, Daldinia eschscholtzii, Pseudopestalotiopsis chinensis and Phyllosticta capitalensis isolated from leaves of C. sinensis in Sri Lanka were evaluated for growth inhibition against plant pathogens; Fusarium sp., L. theobromae, Pestalotiopsis sp. and S. sclerotiorum using the dual culture assay and volatile compound-mediated inhibition assay. All the fungal endophytes used in this study exhibited antifungal activity against Fusarium sp., Pestalotiopsis sp. and S. sclerotiorum in the dual culture assay on PDA. Daldinia eschscholtzii (67.30%) and C. gloeosporioides (61.54%) showed strong antagonistic activity against S. sclerotiorum, while P. capitalensis (42.30%) demonstrated moderate activity. All the endophytic fungal strains showed moderate antifungal activities against Fusarium sp. The percentage growth inhibitions of Pestalotiopsis sp. by all the endophytic isolates tested were below 25.00%. In the volatile compound-mediated inhibition assay, none of the endophytic isolates showed visible inhibition against the phytopathogens used. Conclusion, significance and impact of study: In this study, the fungal endophytes which showed potential antagonistic activity against the tested phytopathogens can be used to develop commercialized products of fungal biocontrol agents (BCAs) for controlling plant fungal diseases.
Effect of pre-treatments with natural compounds for controlling anthracnose in papaya variety Red Lady
(Journal of Horticulture and Postharvest Research, 2023) Kahawattage, A.; Hansini, N.; Daranagama, D.; Ranasinghe, C.
Purpose: Papaya (Carica papaya L.) is an economically important fruit crop affected by anthracnose caused by Colletotrichum gloeosporioides. The study was carried out to test two essential oils; Citronella oil and Cinnamon oil and two leaf extracts; Lantana camara and Ocimum tenuiflorum on four occasions of fruit development as pre-treatment assay in the field condition. Research Method: Essential oils were prepared as an emulsifier and leaf saps were extracted from dried leaves and both were set to 10% concentration. The experiment was conducted in a two-factor factorial experiment with Randomized Complete Block Design. Five treatments including the control were applied for four blocks representing stages of fruit development. Disease severity (0–5 scale) and disease severity index were calculated and statistically analyzed using ANOVA, MINITAB and Tukey’s pairwise analysis. Findings: According to the obtained results, four occasions of application of the selected treatment were highly significant with a minimum level of DSI (34.67 ± 4.62). L. camera leaf extract was highly effective as a pre-treatment with the least values for disease severity percentages (5.78 ± 0.43), disease severity score (0.3 ± 0.17) and disease severity index (26.67 ± 6.36). Research limitations: Flower bud initiation was delayed than the date expected due to the unpredicted heavy rainy condition. Originality/Value: The most effective block treatment interaction was shown on three occasions of application of L. camera leaf extract. This study facilitated the development of the most promising pre-harvest management strategy to control anthracnose disease which causes by the fungal pathogen C. gloeosporioides.
Evaluation of antifungal plant extracts against cereal and legume seed-borne pathogens for effective management
(Studies in Fungi, 2022) Navoda, H.; Daranagama, D.
Sri Lanka as an agricultural country needs to manage the seed-borne fungal pathogens that have caused infections and diseases that result in significant crop losses and a decline in yield and productivity. Therefore, it is imperative to apply pathogen management strategies that are environmentally friendly, and economically feasible such as plant extractions, to reduce seed-borne fungi and increase the quality of the seed. This study was aimed at identifying the antifungal efficacy of Allium sativum, Aloe vera, Azadirachta indica, and Zingiber officinale extracts and their effective concentrations to control the seed-borne fungal pathogens; Aspergillus flavus, A. niger, Orbilia foliicola, Rhizopus oryzae, and Talaromyces oumae-annae isolated from Arachis hypogea, Oryza sativa, Vigna radiata, and V. sinensis respectively. Antifungal efficacy was determined by the agar well diffusion method and poisoned food technique. Plant extracts’ effectiveness for seed germination and seed quality was evaluated by pot experiments. Zingiber officinale crude extract exhibited the highest antifungal activity against the tested pathogens which was as effective as Captan 50% (WP), a positive control. Further analysis of the results from the pot experiment revealed that O. sativa, and V. radiata seeds treated with A. indica, and Z. officinale aqueous extracts showed 100% germination percentage. Azadirachta indica, and Z. officinale aqueous extracts are the most effective in promoting seed germination and seedling vigor while A. vera extract is the least effective extract. Comparing the two different extracts, aqueous extracts significantly promote seed germination and increase seedling vigor.
Seaweed-associated fungal endophytes from southern Sri Lanka and their biocontrol potential against selected fungal phytopathogens
(Maximum Academic Press, 2025) Abeygunawardane, S.; Thambugala, K.M.; Kumara, W.; Daranagama, D.
Fungal endophytes are an endosymbiotic group of fungi that live asymptomatically in healthy tissues of plants and macroalgae. Due to their ability to produce bioactive compounds with potential antifungal properties, fungal endophytes that inhabit seaweed have gained significant attention in the search for sustainable biocontrol agents against phytopathogenic fungi and bacteria. The present study is aimed at identifying fungal endophytes that reside inside seaweeds found in the coastal waters of Southern Province, Sri Lanka, and investigating their biocontrol potential against two fungal phytopathogens; Neopestalotiopsis cubana (Sporocadaceae, Amphisphaeriales) and Colletotrichum siamense (Glomerellaceae, Glomerellales). This is the first study to discover fungal endophytes associated with seaweeds found in the waters of Sri Lanka. Eight fungal endophytic strains were isolated from seaweeds; Padina antillarum (Dictyotaceae), Sargassum ilicifolium (Sargassacea), and Ulva lactuca (Ulvophyceae), found in Thalpe, Madiha, and Koggala beaches. Based on ITS-rDNA sequence analyses, they were preliminarily identified as four distinct endophytic fungal species belonging to the genera Aspergillus and Penicillium. Isolated fungal endophytes were tested for their biocontrol potential against two selected fungal pathogens using a dual culture assay. Percent growth inhibition (PI) of the test pathogens was calculated. Among the isolated fungal endophytes, Aspergillus sp. GMBUCC 24–013 showed the strongest antagonistic activity against both C. siamense UKCC 24-012 and N. cubana GMBUCC 24–001 closely followed by Aspergillus sp. GMBUCC 24–007, GMBUCC 24–008, GMBUCC 24–009, and GMBUCC 24–012. Aspergillus sp. GMBUCC 24–006 exhibited the least biocontrol potential against both phytopathogens, while Penicillium sp. GMBUCC 24–010, and GMBUCC 24–011 showed moderate activity.