Papers by Shanthi Wilson Wijeratnam
Journal of Horticultural Science Biotechnology, 2003
The Journal of Horticultural Science and Biotechnology, 2003
Résumé/Abstract Embul banana hands were sprayed with emulsions of the essential oils of Ceylon ci... more Résumé/Abstract 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′ ...
Plant Pathology Journal, 2010
ABSTRACT The antagonistic effect of three local isolates of Trichoderma viride and one local isol... more ABSTRACT The antagonistic effect of three local isolates of Trichoderma viride and one local isolate of Trichoderma harzianum were tested against the pathogenic fungus Sclerotium rolfsii . The latter organism is responsible for major loss due to collar rot of the ornamental crop Zamioculcas zamiifolia in Sri Lanka. The disease causes massive losses. The antagonistic potential of the local isolates against the phytopathogenic fungi Sclerotium rolfsii was investigated in dual culture, poison food technique, pot trials and field trials on Zamioculcas zamiifolia plants. All Trichoderma isolates tested under in-vitro conditions significantly inhibited the growth of S. rolfsii . Of these isolates, Trichoderma viride isolate Tv1, showed highest percentage inhibition and was thus selected for in vivo field trials. Data recorded from bi monthly field application of this organism over the two growing seasons, confirmed the success of the treatment in controlling collar rot disease at the economic threshold level. Field application of testing isolate T. viride Tv1 as a conidial suspension (1011 cfu mL-1) greatly reduced the disease incidence of Zamioculcas zamiifolia plants by a percentage of 75.54%. On farm mass production of this isolate was developed to help facilitate the establishment of an integrated eco-friendly disease management system for growers of Zamioculcas zamiifolia . Different media was also evaluated to mass produce the Trichoderma isolate. The media evaluated in this study included the solid substrates barley seeds, paddy, cow pea, maize and sorghum and semi solid, liquid substrates such as potato dextrose, rice extract, paddy extracts, respectively. Although mycelial growth was fastest in barley and paddy media. And the highest yield of spores of the Trichoderma isolate was observed 7 days after inoculation in Barley and Paddy media.
Journal of Horticultural Science and Biotechnology
ABSTRACT
Journal of Entomology, 2011
Asian Journal of Plant Pathology, 2009
Journal of the National Science Foundation of Sri Lanka, 2012
ABSTRACT Anthracnose, stem-end rot and brown spot were identified as the common post-harvest dise... more ABSTRACT Anthracnose, stem-end rot and brown spot were identified as the common post-harvest diseases of rambutans in the Western Province of Sri Lanka. The causative organisms of these diseases were isolated and identified as Colletotrichum gloeosporioides (Penz .) Sacc., Botryodiplodia theobronzae Pat . and Gliocephalotrichu~n microchlamydosporuni. J. A. Mey, B. J. Wiley & E.G. Simmons, respectively. The pathogenicity of these three fungi was proved by adopting Koch's postulates .
I International Symposium on Papaya, 2007
ABSTRACT The potential use of chitosan, as an antifungal agent to reduce anthracnose disease on p... more ABSTRACT The potential use of chitosan, as an antifungal agent to reduce anthracnose disease on papaya during storage was investigated. Chitin extracted from locally available prawn waste was used to prepare N,O-carboxymethyl chitosan. The effective concentration of chitosan formulation (from 0.1 to 3%) to inhibit radial mycelial growth was selected via a series of experiments on potato dextrose agar. The selected effective chitosan concentration was then tested on papaya var. Rathna. In vitro studies revealed complete inhibition of radial mycelial growth of the pathogen at 1% chitosan and above. Chitosan at a concentration of 1% in vivo significantly reduced both disease incidence and severity on papaya fruit. Significant changes were observed in chitosan-treated fruit with respect to fruit firmness, rate of respiration and CO2 concentration in the internal cavity of the fruit while other physicochemical and organoleptic characters of the fruit were not affected. Chitosan at a concentration of 1% showed improved fruit firmness after ripening, protected the fruit from decay and kept the fruit quality at an acceptable level (with 80% marketability) throughout the storage period of 14 days at 13.5°C and 95% relative humidity followed by two days at ambient temperature (28± 2°C).
Journal of the National Science Foundation of Sri Lanka, 2011
Journal of the National Science Foundation of Sri Lanka, 2013
New Disease Reports, 2014
Journal of the National Science Foundation of Sri Lanka, 2010
Journal of the National Science Foundation of Sri Lanka, 2009
Sharma/Biological Controls for Preventing Food Deterioration, 2014
Anthracnose ( Colletotrichum gloeosporioides ) and stem end rot ( Botryodiplodia theobromae ) are... more Anthracnose ( Colletotrichum gloeosporioides ) and stem end rot ( Botryodiplodia theobromae ) are the two most prevalent diseases that contribute sig nificantly to post harvest loss of papaya, mango and rambutan in Sri Lanka. The problem is compounded by the home garden system of horticulture practised in the country. The objectiv e of this study was to test the ability of these pathogens to cause disease by cross infection betwe en crops and to provide information that would facilitate an integrated non chemical means o f controlling post harvest loss due to disease. Thus C. gloeosporioides and B. theobromae were isolated from respective disease carrying mango, papaya and rambutan fruits. Pure cultures of each isolate were maintained on Potato Dextrose Agar at 28°C. The antagonistic effect of a local isolate of Trichoderma harzianum was tested via in vitro bioassays against the above iso lates. Host specificity trials were conducted on mango (var. Karthakolomban) and papaya (var. R...
Postharvest Biology and Technology, 2005
Black rot of pineapple (Chalara paradoxa (De Seyen.) Sacc.) is a common postharvest problem in ma... more Black rot of pineapple (Chalara paradoxa (De Seyen.) Sacc.) is a common postharvest problem in many countries. Consumer resistance to the use of fungicides has precipitated the need for alternative means of controlling the disease. In vitro studies on heat-treated (50 • C for 3 min) spores of the pathogen showed a mean colony count of 11 ± 0.7, following 48 h incubation at 28 • C, while plates with heat-treated spores at 54 and 58 • C showed a mean colony count of 1 ± 1.0 and 1 ± 0.7, respectively. Pineapples inoculated with 10 4 spores/ml, C. paradoxa, followed by a hot water dip treatment at 54 • C for 3 min were free of disease when stored at 10 • C for 21 days followed by 48 h at an ambient temperature (28 ± 2 • C). Inoculated dip-treated fruit held at 28 ± 2 • C for 6 days also remained healthy. However, characteristic symptoms of the disease were observed in fruit that were inoculated and held as controls under similar storage conditions, with no hot water dip treatment. No significant difference occurred between hot water dip-treated and untreated controls with respect to flesh and shell colour of fruit, ascorbic acid levels and titratable acidity. Mean ascorbic acid level was 18.8 mg/100 g in fruit stored at 10 • C compared with 9.3 mg/100 g in fruit stored at 28 ± 2 • C, irrespective of whether they were inoculated or non-inoculated fruit. A significant difference (p < 0.05), in total soluble solids (mean Brix of 14 • ), occurred in hot water treated fruit compared with untreated fruit (mean Brix of 11.5 • ), irrespective of storage temperature.
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Papers by Shanthi Wilson Wijeratnam