Browsing by Author "Abeywickrama, K."

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Aloe vera gel and cinnamon essential oils-incorporated Aloe vera on stem-end rot control of mango (cv. Karthakolomban) using dip treatment
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Karunarathna, N.S.N.; Abeywickrama, K.
Stem-end rot (SER) is a major post-harvest disease of mango worldwide. Naturally occurring biologically active compounds from plants are expected to be more suitable and less harmful than synthetic fungicides. Current research was carried out to investigate the applicability of Aloe vera gel and cinnamon bark oil and cinnamon leaf oil-incorporated Aloe vera gel in controlling SER and extending post-harvest shelf life of mango (cv. Karthakolomban). Dip treatments of A. vera gel and cinnamon bark oil (2.0 μL/mL) and cinnamon leaf oil (2.0 μL/mL) incorporated A. vera gel were carried out for 90-day old mango fruits and their pathological, physicochemical, sensory properties and percentage shriveling were evaluated after 10-day storage at 12-14 ℃. After the initial dip treatment trial, a scaling up experiment was conducted using the best treatments where treated and control mangoes were placed in ventilated corrugated fiberboard boxes instead of plastic trays to store mango at 12-14 ℃. Statistical analysis of the results was carried out using MINITAB 18 statistical software. Data with respect to physicochemical properties were analyzed using One-way ANOVA and Tukey’s multiple comparison test. Kruskal Wallis non-parametric test was used to analyze data with respect to pathological, shriveling and sensory properties. Dip treatments of Aloe vera gel in combination with cinnamon leaf and bark oils reduced SER severity of mango to 3.0% in both trials once fruits were subjected to induce ripening. A. vera gel treatment reduced SER severity of mango to 6.0%. A. vera gel, cinnamon bark and leaf oil-incorporated A. vera gel treatments significantly reduced SER severity of mango in comparison to the negative control (distilled water) which showed SER severity of 19.0%. Physicochemical properties namely total soluble solids, titratable acidity, pH, firmness and weight loss of A. vera gel and gel plus oil treated mangoes were similar to the negative control fruits according to the statistical analysis. Percentage shriveling of mango subjected to A. vera gel treatments was reduced to 0- 0.4% compared to the uncoated control fruits which indicated a shriveling of 1.6%. Sensory properties of mango did not demonstrate any drastic alteration between all treatments. Current ecofriendly treatment strategies could be introduced to horticulture industry to reduce post-harvest loss of mango in local trade, during transportation and exportation via air cargo within 10 days.
Antifungal activity of Croton aromatics L. in vitro, against post-harvest fungal pathogens isolated from tropical fruits
(Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka, 2016) Wijesundara, S.A.D.T.L.; Kannangara, B.T.D.S.P.; Abeywickrama, K.
Assessment of phytochemicals and antifungal effect of Croton aromaticus against postharvest fungal pathogens isolated from tropical fruits
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesundara, S.A.D.T.L.; Kannangara, S.; Abeywickrama, K.
Chemical control using synthetic chemical fungicides is still the most common method of controlling postharvest diseases of fruits. Plant extracts which are rich in antimicrobial secondary metabolites such as terpinoids, alkaloids, saponins and flavonoids could be possible alternatives for synthetic fungicides. Current study was focused on evaluating the antifungal effect of ethanolic extract of Croton aromaticus (Kappettiya) leaves in vitro against mycelial growth and the spore germination of postharvest fungal pathogens isolated from fruits of banana (Colletotrichum musae, Rhizopus sp., Lasiodiplodia theobromae) papaya (Rhizopus stolonifer, Colletotrichum gleosporioides, Lasiodiplodia theobromae) and mango (Alternaria alternata, Pestalotiopsis mangiferae, Lasiodiplodia theobromae). Surface sterilized diseased banana, papaya and mango fruit tissues were cultured on PDA plates in order to obtain pure cultures of possible fungi and they were identified by morphological and microscopic characteristics, using identification keys. Inhibitory effect of the ethanolic extract of C. aromaticus against test pathogens were investigated by well diffusion method using PDA medium, by incorporating crude extract dissolved in DMSO, ranging from 1 mg/ml up to 300 mg/ml concentrations along with the positive (Captan) and negative (DMSO) controls. Significant (P < 0.05) inhibitory effects were exhibited by the ethanolic extract of C. aromaticus leaves against all test pathogens except L. theobromae. The highest mycelial growth and spore germination inhibition of most of the pathogens were observed at 100 mg/ml. The lowest Minimum Inhibitory Concentration of the leaf extract (5 mg/ml) was observed for spore germination inhibition of C. gleosporioides and P. mangiferae. TLC analysis revealed four compounds having Rf values of 0.551, 0.672, 0.810 and 0.913. Phytochemical screening of ethanolic extract revealed the presence of alkaloids, terpenoids, quinones, phytosterols and flavonoids. Current findings indicate the potential use of ethanolic extract of C. aromaticus leaves in controlling banana, papaya and mango postharvest fungal pathogens in vitro.
Basil oil plus aluminium sulfate and modified atmosphere packagingcontrols Crown rot disease in Embul banana (Musa acuminata, AAB) during cold storage
(Elsevier, 2017) Siriwardanaa, H.; Abeywickrama, K.; Kannangaraa, S.; Jayawardena, B.; Attanayake, S.
tEffect of basil oil spray treatment in combination with modified atmosphere packaging was investigatedin controlling crown rot and extending the shelf life of Embul banana (Musa acuminata, AAB) at 12–14◦C.Embul banana fruits were treated with 1% aluminium sulfate, 1% aluminium sulfate + 0.4% basil oil and dis-tilled water (control). Treated banana samples were packed in Low Density Polyethylene bags and storedat 12–14◦C. In-package gases were analysed after 14 days of cold storage. Physicochemical properties,nutritional properties, sensory properties and crown rot disease severity as well as residues in treatedbanana peel were determined in ripening induced fruits. Test marketing trials were conducted in fruit out-lets in Dambulla and Kiribathgoda, Sri Lanka where treatments were provided to consumers and staff toobtain feedback on the quality of treated banana. At the end of 14 days, O2in packages remained between3.1–3.7% while CO2varied from 4.2 to 4.7%. 1% aluminium sulfate + oil treatment significantly controlledcrown rot disease compared to others. Most of the physicochemical, sensory properties of aluminiumsulfate + basil oil treated banana were not significantly different compared to control whereas nutritionalproperties of treated samples showed no drastic changes compared to control. Treated samples scoredhigher for peel colour and taste over control samples, by staff and consumers of fruit outlets. Consumerspreferred basil oil treated banana over untreated due to their sweet and pleasant taste. Insignificantamount of residues persisted in treated banana. This current safe, eco-friendly treatment strategy couldbe recommended in preparing Embul as well as other banana varieties belonging to Musa acuminata, AABgroup for commercial scale export to various destinations which require a transit time of two weeks.
Bioactivity of leaf volatiles of Azadirachta indica A. Juss. and Murraya koenigii Spreng. against Sitophilus oryzae L.(Coleoptera: Curculionidae)
(National Science Foundation of Sri Lanka., 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugaliyadde, L.; Abeywickrama, K.
Repellent activity, fumigant and contact toxicities of leaf volatiles of Azadirachta indica A. Juss. and Murraya koengii Spreng. were evaluated against Sitophilus oryzae L. In the dual choice repellency test with A indica leaf volatiles, significantly higher number of insects was repelled at doses above 100 mg, whereas volatiles of At. koenigii attracted insects at 25 mg dose and repelled at 300 mg dose. In the fumigant toxicity test 100% mortality was observed at the concentration of 32.5 mg/ml, 3 days after the treatment with 2 volatiles separately. The L C n values for fumigant toxicities were 13.5 and 22.5 mg/ml for A. indica and At. koenigii volatiles, respectively. In contact toxicity test, 100% mortality was observed immediately after 48 h contact exposure of insects at concentrations of 0375 and 0.125 mg/cm1 of A indica and At. koenigii respectively. The respective L C W values were 0.12 and 0.08 mg/cm1 for A. indica and At. koenigii leaf volatiles.
Dip treatment of Aloe vera gel and Aloe vera in combination with cinnamon essential oils on stem-end rot of mango cv. ‘Karthakolomban’
(2022) Karunarathna, N. S. N.; Abeywickrama, K.; Kodituwakku, T. D.
This study was conducted to investigate the applicability of Aloe vera gel alone and mixed with cinnamon leaf and bark oil in controlling stem-end rot (SER) and extending the shelf life of mango cv. ‘Karthakolomban’. Mangoes were subjected to dip treatments of Aloe vera gel and Aloe vera gel in combination with cinnamon bark oil (2.0 μL/mL) and cinnamon leaf oil (2.0 μL/mL) and their pathological, physicochemical, sensory properties, and percentage shriveling were evaluated after a 10 d storage period at 12-14℃. Dip treatment of Aloe vera gel + cinnamon oils and Aloe vera gel reduced SER by 3.0 - 6.0%. Physicochemical and sensory properties did not show drastic alterations among all treatments and controls. Mangoes subjected to Aloe vera gel + cinnamon oil treatments demonstrated 0% shriveling. Uncoated fruits showed the highest shriveling. The findings highlight that Aloe vera gel may have a better prospect in the preservation and quality maintenance of mango in combination with cinnamon oils.
A disease severity index to monitor stem-end rot development in Mango (cv. Karutha Colomban) and the assessment of pathogenicity of associated pathogens
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Kodituwakku, T.D.; Abeywickrama, K.; Karunanayake, K.O.L.C.
Mango (Mangifera indica L.) is a renowned tropical fruit consumed in Sri Lanka. Significant postharvest losses of mango are caused by diseases which affect the quality of fruits. Stemend rot (SER) of mango is a disease caused by a group of fungal pathogens. Disease severity indices are important for assessing the extent of damage caused by a disease to develop suitable control strategies. An index was developed to evaluate the disease development and the level of severity of SER in mango (cv. Karutha Colomban (KC). Pathogenicity of four fungi isolated from mango with SER was also investigated to find out their contribution for SER development in mango. Four mango fruits (90-days old) washed in tap water followed by sterile distilled water were placed on a plastic tray at room temperature. One selected fruit showing a gradual development of SER was photographed daily. Diseased area of the fruit in each photograph was estimated by DIGIMIZER (Version 5.3.4) software and the disease severity was determined as percentage SER (%SER). An index was prepared using the photographs with percentage SER values. Four fungal pathogens (Lasiodiplodia theobromae, Phomopsis sp., Pestalotiopsis sp. and Xylaria feejeensis) were isolated from mango with SER and their identity was confirmed by PCR using universal primers (ITS1 and ITS4) and DNA sequencing. Healthy mango fruits (90-day old) washed in tap water were surface sterilized with 0.1% sodium hypochlorite and subsequently washed in sterile distilled water. Stem-ends of the fruits were wound inoculated with 7-day old mycelial plugs of each fungal pathogen separately and all four pathogens together. Fresh PDA plugs served as the control. Inoculated fruits were incubated in moist plastic chambers at room temperature for 7 days. Each treatment comprised of four replicates and the experiment was repeated. Percentage SER of each fruit was determined based on the developed index. Mean percentage SER resulted by the combination of all four pathogens and L. theobromae, Pestalotiopsis sp. and X. feejeensis, separately were found to be 67.00 ± 4.77%, 66.75 ± 3.84%, 61.13 ± 3.32% and 60.38 ± 4.58% respectively and there was no significant difference between their pathogenicity (MINITAB 18). The least pathogenicity (16.50 ± 1.66%) was observed in fruits inoculated with Phomopsis sp. and percentage SER of the control was 0.88 ± 0.23% L. theobromae, X. feejeensis and Pestalotiopsis sp. were identified as the major contributors for SER in mango and this may be the first reported evidence in Sri Lanka on X. feejeensis as a potential SER pathogen of mango (cv. KC).
Effect of Croton aromaticus leaf extracts in controlling Crown Rot disease of Embul banana.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dilhani, S.; Wimalasiri, S.; Abeywickrama, K.; Kannangara, S.
Embul banana (Musa acuminata-AAB) is one of the major dessert fruits in Sri Lanka, widely consumed by all economic groups due to its small size and characteristic flavour. Although Embul banana has high potential for export market storage and export of this commodity over long distances is difficult in consequence of postharvest fungal diseases. The most common and serious postharvest disease that affect Embul banana is Crown Rot (CR). Use of synthetic fungicides is the widely used method in controlling postharvest diseases of fruits worldwide. The interest of finding natural bioactive components has increased due to the harmful effects of synthetic fungicides on environment and health. In the present study, antifungal activity of aqueous, hot water and ethanolic leaf extracts of Croton aromaticus in controlling CR disease of Embul banana was investigated in vivo. Embul banana hands (85-days mature) were treated with C. aromaticus aqueous, hot water 100% (v/v) and ethanolic leaf extracts (400 mg/ml) alone or in combination with alum (1%) or distilled water (control) were stored in modified atmosphere packaging at 12-14 0C for 14 days. Each treatment comprised of 4 replicates. In-package gases were analysed on initial day and thereafter up to 14 days. Physicochemical properties (pH, firmness, TSS, TA), sensory properties (peel colour, flesh colour, aroma, flavour, taste, overall acceptability), and Crown Rot disease severity were determined in ripening induced fruits after 7 and 14 days of storage period. Statistical analysis was done using the MINITAB 16 statistical package. Oxygen levels measured were observed to be amaintained at 2.2-4.4% while CO2 levels were maintained at 5.5-8.4% in all packages at the end of 14 day storage period. C. aromaticus ethanolic leaf extract (400 mg/mL) was the most effective extract in controlling crown rot disease of Embul banana compared to aqueous and hot water leaf extracts. Physicochemical properties of Embul banana treated with C. aromaticus leaf extract alone and in combination with alum were not significantly different compared to control except for TSS and TA. Most of the sensory properties were preferred by sensory panelists with score values of above 6 indicating the good quality of samples. C. aromaticus ethanolic leaf extract + alum in combination with modified atmosphere packaging and cold storage could be used as a potential safe way of controlling Crown Rot disease of Embul banana.
Effect of Ocimum basilicum oil plus modified atmosphere packaging of quality of Embul banana
(2016) Abeywickrama, K.; Siriwardana, H.; Kannangara, S.; Jayawardena, B.
The effect of spraying essential oils of Cymbopogon nardus, Cymbopogon flexuosus and Ocimum basilicum on postharvest diseases and storage life of Embul banana
(The Journal of Horticultural Science and Biotechnology, Taylor & Francis., 2003) Anthony, S.; Abeywickrama, K.; Wijeratnam, S.W.
Embul banana hands were sprayed with emulsions of the essential oils of Ceylon citronella (Cymbopogon nardus) (0.4% v/v) lemon grass Cymbopogon flexuosus (0.16% v/v), or Indian sweet basil (Ocimum basilicum) (0.16% v/v) and stored cool (13.5 ± 1°C) or at ambient temperature (28 ± 1°C) at 94% relative humidity. A benomyl spray (0.1% w/v) was included as a standard fungicide control treatment. The effects of the essential oils on post-harvest diseases, and on organoleptic and cosmetic quality and various properties of the fruit (percentage weight loss, changes in fruit firmness, total soluble solids and titratable acidity) were determined. Treatment with Ocimum basilicum oil controlled crown rot and anthracnose, enabling bananas to be stored for up to 21 d at 13.5 ± 1°C without any detrimental effect on their organoleptic properties; results were comparable with treatment with benomyl. Rapid-ripening induced by ethral after cool storage resulted in better quality bananas. The oil of C. nardus affected the texture and flavour of the fruit and that of C. flexuosus did not give complete control of crown rot. Spraying Embul bananas with emulsions of the essential oil of Ocimum basilicum prior to cool storage can be recommended therefore as a safe, cost-effective method, with commercial potential, for controlling post-harvest diseases and extending storage life.
Effect of the essential oil of Cymbopogon nardus on Aspergillus flavus Link isolated from Sri Lankan paddy and rice
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2002) Paranagama, P.A.; Abeysekera, K.H.; Abeywickrama, K.; Nugaliyadda, L.
Effects of Fusarium moniliforme culture extracts and fumonisin B1 on DNA, RNA and protein synthesis by baby hamster kidney cells
(Springer Netherlands., 1998) Abeywickrama, K.; Bean, G.A.; Kennedy, K..A.
Baby hamster kidney cells (BHK-21) were exposed to culture filtrates of 4 Fusarium moniliforme isolates containing varying levels of fumonisin B1 (FMB1) and the effects upon RNA, DNA and protein synthesis were monitored. Cells were also grown on medium amended with FMB1 only for comparison. After 24 h incubation FMB1 (100 μg/100 ml medium) reduced protein synthesis by 4% and by 18% after 48 h. Culture filtrates containing the highest levels of FMB1 also caused the greatest inhibition in protein synthesis after 24 h but after 48 h protein synthesis levels were the same as controls even though the FMB1 level was 360 μg/100 ml. Only FMB1 reduced DNA synthesis, by 8% after 24 h but after 48 h DNA levels had increased by 40 % over controls. The culture filtrates containing the highest levels of FMB1 (360 μg/100 ml) reduced DNA synthesis more than 50% after 24 h and 48 h. Culture filtrates containing lesser amounts of FMB1 in some instances stimulated DNA synthesis and inhibited it in others. There was also no correlation in the level of FMB1 with the inhibition of RNA synthesis by BHK cells. It appears that metabolites other than fumonisin produced by F. moniliforme in culture can affect and both stimulate and inhibit RNA, DNA and protein synthesis by BHK cells.
Efficacy of Alum Treatment and Vacuum Packaging in Controlling Crown Rot Disease of Cavendish Banana
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Siriwardana, H.; Abeywickrama, K.; Kannangara, S.; Jayawardana, B.
Cavendish is the widely grown banana cultivar in the world today and the most prominent cultivar in the international trade. Crown rot, one of the most drastic postharvest diseases of Cavendish banana can cause severe postharvest loss both in the local and export markets. In the industry, cut crowns of banana are treated with fungicides to control this disease. Due to hazardous effects of fungicides, finding suitable alternatives in the management of crown rot of banana is essential. In this study, effect of alum (potassium aluminium sulphate) in combination with vacuum packaging was investigated in controlling crown rot disease and extending the shelf life of Cavendish banana at cold storage. Twelve week mature Cavendish banana (Musa acuminata, AAA, Grande Naine cultivar) hands were treated with 1% (w/v) alum or distilled water (controlled). Treated and control fruits were packed in Low density polyethylene bags, air inside bags were removed using vacuum and placed in fiber board cartons and stored in a cold room at 12-14 ºC. Each treatment comprised 10 replicate boxes each with 5 hands. In-package gases were analyzed after 14 days of cold storage. Physicochemical properties (pH, TSS, TA and firmness), sensory properties (peel colour, flesh colour, aroma, flavour, taste and overall acceptability) and crown rot disease severity were determined in ripening induced fruits. Test marketing trials were conducted at CIC fruit outlet in Dambulla, Sri Lanka where treated fruits were provided to consumers and staff to obtain feedback on the quality of treated banana. At the end of 14 days, O2 in packages remained between 5.0 to 5.8% while CO2% ranged from 4.9% to 5.8%. Alum in combination with vacuum packaging significantly controlled crown rot disease of Cavendish banana compared to the control. Physicochemical and sensory properties were unaffected by alum + vacuum packaging treatment when compared to control. Treated banana obtained higher score values from the customers and staff of fruit outlets for the sensory properties compared to the control. Therefore, this eco-friendly treatment strategy could be recommended in preparing Cavendish banana for local market as well as commercial scale export to various destinations which require a transit time of two weeks.
Efficacy of basil oil and alum in controlling crown rot disease of Cavendish banana (Musa acuminata, AAA) during cold storage
(2016) Siriwardana, H.; Abeywickrama, K.; Kannangara, S.; Attanayake, S.
Effect of Ocimum basilicum (basil) oil spray treatment, alum in combination with modified atmosphere packaging (MAP) was investigated in extending the shelf life of Cavendish banana (Musa acuminata, AAA - Grand Naine cultivar) at 12-14 0C. Twelve week mature Cavendish banana fruits were treated with 1% (w/v) alum (Potassium aluminium sulphate), 1% (w/v) alum + 0.4% (v/v) basil oil, 0.5 g/L carbendazim and distilled water (control). Treated banana samples were packed in Low Density Polyethylene bags and stored at 12-14 0C. In-package gases were analysed every seven days up to 28 days of storage. Physicochemical properties (pH, firmness, TSS, TA), sensory properties (peel colour, flesh colour, aroma, flavour, taste, overall acceptability) and crown rot disease severity were determined in ripening induced fruits after each storage period. At the end of 28 days of storage O2 in all packages remained between 5.0- 5.4% while CO2 varied from 5.1 to 5.6%. Further, treatment of 1% alum+0.4% basil oil effectively controlled crown rot disease of Cavendish banana completely up to 21 days. Most of physicochemical and sensory properties of treated banana were not adversely affected by the treatment.
Evaluation of antifungal effect of Croton aromaticus on storage life extension of banana
(2016) Dilhani, S.; Wimalasiri, S.; Abeywickrama, K.; Kannangara, S.
Effect of Croton aromaticus aqueous, hot water and ethanolic leaf extracts alone and in combination with alum against banana crown rot causing fungal pathogens were investigated using 96 well plate bioassay and liquid bioassay in vitro. According to the results of 96 well plate assay, C. aromaticus aqueous extract successfully inhibited conidial germination of C. musae up to 96.9%. Percentage germination inhibition of F. proliferatum is less than that of C. musae. Hot water extract expressed higher conidial germination inhibition of F. proliferatum. Conidial germination of C. musae was 100% inhibited at the concentration of 600 (%w/v) of ethanoic extract and at the same concentration F. proliferatum was inhibited by 90.4 %. Alum was fungicidal against C. musae and L. theobromae. C. aromaticus leaf extract in combination with alum controlled F. proliferatum more effectively compared to leaf extract alone. During liquid bioassay, ethanolic leaf extract totally inhibited the mycelial growth of test pathogens at the concentration of 800 (%w/v). Among three tested extracts, ethanolic extract was most effective in inhibiting both spore germination and mycelial growth of crown rot causing fungal pathogens.
Formulation and stabilization of Trichoderma spp. in selected carrier materials.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Botheju, W.S.M.; Hewavitharana, N.,; Kannangara, S.D.P.; Abeywickrama, K.
Trichoderma spp. are one of the major biocontrol agents which have the ability to act against large numbers of foliar and soil borne pathogens and are eco-friendly good plant growth promoting agents. Present investigation was carried out with an attempt to determine 1) the best organic carrier material in which the viability and antagonistic activity retain for a sufficient duration and 2) optimum temperature at which the product can be stored without losing the viability and antagonistic activity. In the present study, three Trichoderma spp. (T. asperellum, T. harzianum and T. virens) were formulated in three carrier materials - coir dust, saw dust and waste of polished rice, which were rich in lignocellulosic organic compounds, nitrogen and mineral salts. In the preparation procedure, glucose and starch were added as carbon sources and cow dung was also added as a source of nitrogen as Trichoderma spp. require sufficient amounts of carbon and nitrogen sources for their growth and development. Three Trichoderma spp. were then inoculated separately (ten mycelial blocks with 1cm diameter from 7-day old cultures) into the carrier materials in sterilized polypropylene bags aseptically. Each treatment comprised of six replicates. Shelf life of these formulated products were studied along with viability tests, using spread plate method from which colony forming units were observed at three week intervals. Mean values of measurements were statistically analyzed using ANOVA and Tukey’s pair wise test (Minitab 16). Antagonistic activity of three Trichoderma spp. against three post-harvest pathogens (Colletotrichum musae, Fusarium oxysporum, Pestaliopsis microspora) were monitored using dual culture method at room temperature (30°C) and 4°C where growth inhibition was measured. All three types of carrier materials were good media for the formulation of all three Trichoderma species and when reisolated, the highest Colony Forming Units were observed in waste of polished rice formulations, at 4°C; [T. asperellum (6.23 log CFU/g), T. harzianum (5.92 log CFU/g) and T. virens (6.04 log CFU/g)] compared to other two carrier materials. Optimum temperature for the storage of formulated products was 4°C that maintained the viability and antagonistic activity of Trichoderma propagules for 130 days compared to the storage at room temperature. However, the values for CFUs of all three Trichoderma spp. in three carrier materials were slightly reduced after storage at 4°C which was not significant. The growth of all three post-harvest pathogens were inhibited by the three Trichoderma spp. and the inhibition values ranged from 36.5% – 83.6%. Growth inhibition values obtained at room temperature (30°C) and 4°C were not significantly different. Among the cost effective three carrier materials at two different temperatures, waste of polished rice at 4°C was found to be significantly effective in retaining the viability and antagonistic ability of the tested Trichoderma species. This may be due to the presence of optimum C contents (35%), C:N ratio (28.42) and pH (6.7) which enhance the production of sufficient propagules of three Trichoderma spp.
Fungicidal activity of essential oils of Cinnamomum zeylanicum (L.) and Syzygium aromaticum (L.) Merr et LM Perry against crown rot and anthracnose pathogens isolated from banana
(Blackwell Science Ltd., 2002) Ranasinghe, L.; Jayawardena, B.; Abeywickrama, K.
Aims: To develop a post-harvest treatment system against post-harvest fungal pathogens of banana using natural products. Methods and Results:Colletotrichum musae was isolated and identified as the causative agent responsible for anthracnose peel blemishes while three fungi, namely Lasiodiplodia theobromae, C. musae and Fusarium proliferatum, were identified as causative agents responsible for crown rot. During the liquid bioassay, cinnamon [Cinnamomum zeylanicum (L.)] leaf, bark and clove [Syzygium aromaticum (L.)] oils were tested against the anthracnose and crown rot pathogens. The test oils were fungistatic and fungicidal against the test pathogens within a range of 0·03−0·11% (v/v). Conclusions: Cinnamon and clove essential oils could be used as antifungal agents to manage post harvest fungal diseases of banana. Significance and Impact of the Study: Cinnamon and clove essential oil could be used as alternative post-harvest treatments on banana. Banana treated with essential oil is chemically safe and acceptable to consumers. Benomyl (Benlate), which is currently used to manage fungal pathogens, can cause adverse health effects and could be replaced with volatile essential oils.
In vitro and in vivo Application of Eco-friendly Treatments to Control Postharvest Stem-end Rot of Naturally Infected Avocado (cv. Pollock)
(The Journal of Agricultural Sciences - Sri Lanka, 2021) Nilmini, R.K.; Kodituwakku, T.D.; Abeywickrama, K.; Kuruppu, M.
Purpose: Stem-end rot (SER) is an endophytic fungal infection of avocado causing significant postharvest losses, affecting its marketability. This study was conducted to identify effective concentrations of selected eco-friendly essential oils and chemicals to control SER pathogens by conducting in vitro bioassays and to develop treatments to control SER in naturally infected avocado (cv. Pollock) using less hazardous alternatives to synthetic fungicides. Research Method: In vitro disc volatilization and poison food bioassays were conducted to identify inhibitory concentrations of some essential oils and chemicals against SER pathogens. Avocado fruits were subjected to eco-friendly fumigation and dip treatments and their pathological, physicochemical and sensory properties were assessed after 7 days of storage at 15 °C. Findings: Disc volatilization bioassay revealed that 5 µL/plate clove oil was most effective against Lasiodiplodia theobromae, Diaporthe nelumbonis and Fusarium oxysporum. According to Poisoned food bioassay, 5% (w/v) sodium bicarbonate and 0.07% (v/v) acetic acid were highly effective against the test pathogens. SER incidence of avocado fruits has been successfully delayed for 7 days after subjecting to fumigation treatment with clove oil and dip treatments with sodium bicarbonate and acetic acid, followed by storage at 15 °C. None of the treatments adversely affected physicochemical and sensory properties of avocado. Originality/Value: Treatments could be further improved by conducting a medium-scale in vivo trial to obtain good quality avocado with higher consumer acceptance.
Morphological and molecular identification of fungi for their association with postharvest fruit rots in some selected citrus species
(2022) Jayasekara, A.; Daranagama, A.; Kodituwakku, T.D.; Abeywickrama, K.
Purpose: The availability of fresh Citrus fruits is limited by their susceptibility to invasion by microbial pathogens which leads to cause serious postharvest losses. The present study was carried out to isolate and morphologically identify postharvest fungal associations from selected Citrus fruit species (C. sinensis, C. limon, C. crenatifolia and C. medica) and to confirm their identity by molecular characterization. Research method: Postharvest fungal associations of selected Citrus fruit species were isolated, and identification was done based on morphological characteristics. Confirmation of fungal associations was done through phylogenetic analysis of newly generated ITS sequencing data. Further, frequency of occurrence of each fungal isolate was calculated in three different districts in Sri Lanka. Findings: From the morphological and molecular identification, Collectrichum fructicola, Collectrichum gloeosporioides, Lasiodiplodia theobromae, Aspergillus niger and Pestalotiopsis sp. were recorded from C. sinensis. Neofusicoccum parvum, Collectrichum gigasporium and Aspergillus clavatus were isolated from C. crenatifolia. Further, Lasiodiplodia theobromae and L. pseudotheobromae were the only fungal association isolated from C. limon and C. medica fruit species, respectively. It is worthwhile noting that this is the first report of association of the C. gigasporium and Pestalotiopsis sp. from Citrus fruits in Sri Lanka. Research limitations: Since this research was mainly focused on the isolation and identification of the potential fungal associations, pathogenicity evaluation could not be carried out. Originality/Value: Findings of potential disease causative agents in citrus will be valuable for agriculture sector, to adopt and practice effective strategies to minimize postharvest losses of citrus fruits.
Morphological Characterization and Molecular Identification of Stem-end Rot Associated Fungal Species Isolated from ‘Karutha Colomban’ Mango Fruits in Sri Lanka
(The Journal of Agricultural Sciences - Sri Lanka, 2019) Ekanayake, G.; Abeywickrama, K.; Daranagama, A.; Kannangara, S.
Purpose: Stem-End Rot (SER) is one of the most frequently found mango postharvest diseases in many countries including Sri Lanka. Availability of a significantly detailed study on morphological and molecular characterization of the SER associated fungal species is comparatively low. The present study has been carried out considering the above fact. Research Method: SER disease associated fungi were isolated and identification was carried out using morphological characteristics. Identification was confirmed by phylogenetic analysis of newly generated ITS sequencing data using Maximum Likelihood (ML) with RAxML software (Ver.8.2.10). Findings: From the morphological studies it was observed that the fungal isolates SER1, SER2, SER3 and SER6 produced conidia on Potato Dextrose Agar. Both morphological and molecular results revealed that the isolates of SER1, SER4, SER5, and SER6 which were isolated from diseased Karutha Colomban mango fruits with SER (in Sri Lanka) belong to Lasiodiplodia sp., Nodulisporium sp., Xylaria feejeensis and Pestalotiopsis sp. respectively. Both SER2 and SER3 were confirmed as Phomopsis sp. During the present study two new fungal species (Xylaria spp. and Nodulisporium spp.) were also identified for the first time from SER of Karutha Colomban mango fruits. Research Limitations: The pathogenicity of these isolates will be tested in near future, since the study was mainly focused on the isolation and identification of the SER associated fungal species. Originality/ Value: Results of the present study will be very valuable for stakeholders in Agricultural sector, before designing control strategies at post-harvest level in order to minimize the loss and extend the storage life of mango.