Kandeeparoopan Prasannath | Eastern University, Sri Lanka (original) (raw)

Papers by Kandeeparoopan Prasannath

Research paper thumbnail of Diagnostics of flower blight complex with increasing heterogeneity in macadamia

Phytopathology, 2022

Macadamia is an evergreen tree nut crop cultivated in tropical and frost-free subtropical regions... more Macadamia is an evergreen tree nut crop cultivated in tropical and frost-free subtropical regions worldwide. Flower blight of macadamia is a heterogeneous disease. Currently, the four definitive categories undoubtedly represent only a spectrum of causal pathogens with contrasting lifecycles. Different disease categories seem to result from different types of interaction between organtrophism and environmental factors. Although host genetics influence infection and disease severity, variations in the environment are the most probable explanation for the fluctuating nature of the pathogens and increase in the various types of flower blight. The occurrence of multiple fungal species of Botrytis, Cladosporium, Neopestalotiopsis and Pestalotiopsis highlights the challenges for diagnostics and management. While the efficiency of multi-species qPCR assays relies on species identification, detection at the genuslevel presents a strong modifier that could account for a large proportion of novel species, and also improve characterisation of a range of pathogen subgroups. It appears flower blight causal pathogens are becoming more diverse with time. The qPCR assays developed in this study were used to detect and quantity airborne conidia for each fungal genus associated with flower blight complex in commercial macadamia plantations. The qPCR assays support flower blight risk forecasting and management.

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Research paper thumbnail of Sources, Detection, and Inoculum Quantification of Flower Blight Pathogens in Macadamia

Phytopathology®

Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladospo... more Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladosporium spp., and gray mold caused by Botrytis spp., collectively known as flower blight cause significant yield losses in macadamia. Potential sources of inoculum of the various pathogens in macadamia tree canopy were examined using pathogenicity tests and a multiplex quantitative PCR (qPCR) assay developed in this study. The qPCR assay detected and quantified the relative abundance of the inoculum of flower blight pathogens. The assay revealed that remnant racemes contributed a high amount of inoculum of all the three groups of flower blight pathogens, while the yellow halo leaf spot contributed only Pestalotiopsis/Neopestalotiopsis species. The amount of conidia per gram of remnant racemes ranged from 7 × 103 to 2 × 104 for dry flower disease, 3 × 103 to 1 × 104 for green mold, and 5 to 8 × 103 for gray mold pathogens. Conidia of Pestalotiopsis/Neopestalotiopsis species quantified from l...

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Research paper thumbnail of Etiology of flower blight complex in macadamia

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Research paper thumbnail of Sources and quantification of flower blight pathogens in macadamia

Raceme blights also known as flower blights are used to describe diseases and disorders of macada... more Raceme blights also known as flower blights are used to describe diseases and disorders of macadamia inflorescence worldwide. Flower blights reduce fruit set and control measures are limited. Knowledge of the disease cycle and epidemiological parameters is required. Therefore, the potential sources of inoculum for the three forms of flower blights of macadamia in Australia were investigated. Relative abundance of the inoculum (Ri) in remnant racemes and yellow halo leaf spot in macadamia canopy was quantified and the pathogenicity of the fungal isolates obtained from the plant materials was assessed on developing flowers. Ri >90% was recorded for Neopestalotiopsis species from both the remnant racemes and leaf spot, which indicates the materials are a source of inoculum for dry flower disease. Whereas, Ri <40% was recorded for Botrytis species, the causal agent of grey mould, and Ri = 70% for Cladosporium species, the causal agent of green mould, only from remnant racemes. Con...

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Research paper thumbnail of Biotic risks, pesticide usage and awareness on IPM techniques in paddy cultivation in Polonnaruwa district of Sri Lanka

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Research paper thumbnail of Role of Trichoderma spp. in Biocontrol of Plant Diseases

Microbial Biocontrol: Food Security and Post Harvest Management, 2022

Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a su... more Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a surge. The detrimental impacts of current disease management practices create an urgent need to develop non-chemical and eco-friendly methods. Biological control or biocontrol of phytopathogens is a sustainable and sound approach to overwhelm various threats caused by the existing control measures. Among the biocontrol agents (BCAs), avirulent, filamentous mycoparasitic Trichoderma spp. are well-known for their agricultural application versatility. The host plant-Trichoderma-pathogen interaction plays a pivotal role in plant disease management. Trichoderma spp. network with plant pathogens via direct mechanisms of mycoparasitism, antibiosis and competition while indirectly inducing systemic disease resistance and promoting plant growth and yield when Trichoderma-plant interaction is switched on. The interactions support efficient biological disease control and overall crop recovery from various diseases and ultimately lead to successful crop production. Trichoderma-based BCAs offer significant contributions in the arena of plant protection and disease management. An array of Trichoderma spp. have proven effective against a broad range of plant pathogens by enhancing the plants&#39; overall health and improving their yield. The biocontrol activity, plant-Trichoderma interactions and the efficacy could vary with the type of the pathogens, Trichoderma strain and host plant. Besides, the efficacy and stability of widely used and newly recognized strains of Trichoderma still need to be evaluated under different environmental conditions in the field for successful outcomes.

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Research paper thumbnail of Determination of Pesticide Usage and Its Environmental Impact Quotient in Vegetable Cultivation in Kalpitiya Divisional Secretariat Division of Puttalam District of Sri Lanka

Application of synthetic pesticides has been the main method of controlling pests and diseases in... more Application of synthetic pesticides has been the main method of controlling pests and diseases in crop cultivation. In this context, the objectives of the study were to assess the pesticide usage pattern and determine the environmental impact quotient of pesticide use in vegetable cultivation in Kalpitiya, Sri Lanka. Stratified random sampling method was used to select 100 farmers from Kalpitiya Divisional Secretariat division of Puttalam, which is a predominantly vegetable cultivating area. Pre-tested structured questionnaires were used to collect data during Maha 2016/2017 cropping season. Descriptive statistics and probit model were used to analyze the data. Field Use Environmental Impact Quotient (FEIQ) of pesticides used by the farmers was also determined. The results of the study indicated that the foremost problem in the vegetable cultivation was insect damage (92%) followed by diseases (84%) while weed problem was insignificant. The average extent of cultivation was 2.18 acres where only 14% of respondents’ cultivated land size was greater than 4 acres. Percentage of farmers having more than 5 years of experience in cultivation was 74%. Only 36% of farmers received extension service. Pesticides were applied on vegetable crops by 94% of the farmers. On an average, pesticide application frequency was 4.4, whereas pesticide use (active ingredient) by weight on the vegetable crops was 0.58 kg ha-1. The average FEIQ of pesticide use in the study area was 75.28 ha-1. Probit analysis revealed that educational level, farming experience and access to extension service had a positive and significant (p&lt;0.05) relationship on farmers awareness of risks from pesticide use. Vegetable farmers of this area use extensive amount of pesticides which cause more damage to the environment. Therefore, it is recommended to provide information to the farmers about the judicious use of less toxic pesticides.

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Research paper thumbnail of Study on Risk Identification and Pesticide Usage in Paddy Cultivation in Alayadivembu Divisional Secretariat Division of Ampara District, Sri Lanka

International Conference on Agriculture and Forestry, 2018

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Research paper thumbnail of Evaluation of different casing mixtures for "Makandura White" mushroom production in Sri Lanka

Makandura-White (MK-White) mushroom cultivation requires a special practice, casing. At present, ... more Makandura-White (MK-White) mushroom cultivation requires a special practice, casing. At present, the recommended casing mixture is termite clay, sand, dry cattle manure (3:1:1). However, the availability of termite clay in large quantity is limited. On this background, a study was conducted during June to September 2018 at the Regional Agriculture Research Centre in Makandura, Sri Lanka to find out locally available material that can be easily found and is cost effective for the cultivation of MK-White mushroom. The experiment was arranged in a completely randomized design with seven treatments and three replications. Different combinations of casing mixtures; termite clay, dry cattle manure, dry cannel basin soil, compost and half burnt paddy husk were evaluated for their physico-chemical properties. Further, the effects of casing materials on mycelial growth and pin head formation of MK-White mushroom were determined. There were significant differences (p&lt;0.05) in mycelial growth and pin head formation among the different casing mixtures. The fastest pin head formation and the highest yield of pin heads were recorded in the casing mixture of dry cannel basin soil and compost with a ratio of 3:2. Further, this casing mixture was found to have the optimum level of physico-chemical properties, such as moisture content (44.7%), pH (7.41) and C:N ratio (15:1) to grow MK-White mushroom. Therefore, the casing mixture of termite clay, sand and dry cattle manure which is presently adopted, could be replaced with the readily available dry cannel basin soil: compost (3:2) casing mixture for MK-White mushroom cultivation.

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Research paper thumbnail of Flower blight complex

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Research paper thumbnail of Macadamia integrated disease management (IDM)

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Research paper thumbnail of RNA interference as a promising strategy for plant disease management

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Research paper thumbnail of Leaf spot a possible source of inoculum of dry flower disease in macadamia in Australia

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Research paper thumbnail of Recent Advances in Molecular Diagnostics of Fungal Plant Pathogens: A Mini Review

Frontiers in Cellular and Infection Microbiology, 2021

Phytopathogenic fungal species can cause enormous losses in quantity and quality of crop yields a... more Phytopathogenic fungal species can cause enormous losses in quantity and quality of crop yields and this is a major economic issue in the global agricultural sector. Precise and rapid detection and identification of plant infecting fungi are essential to facilitate effective management of disease. DNA-based methods have become popular methods for accurate plant disease diagnostics. Recent developments in standard and variant polymerase chain reaction (PCR) assays including nested, multiplex, quantitative, bio and magnetic-capture hybridization PCR techniques, post and isothermal amplification methods, DNA and RNA based probe development, and next-generation sequencing provide novel tools in molecular diagnostics in fungal detection and differentiation fields. These molecular based detection techniques are effective in detecting symptomatic and asymptomatic diseases of both culturable and unculturable fungal pathogens in sole and co-infections. Even though the molecular diagnostic ap...

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Research paper thumbnail of Management of postharvest anthracnose of banana using inorganic salts alone and in combination with hot water

Plant Pathology & Quarantine, 2020

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Research paper thumbnail of Characterisation of leaf spots caused by Neopestalotiopsis clavispora and Colletotrichum siamense in macadamia in Australia

European Journal of Plant Pathology, 2020

Extensive leaf spot was observed on all leaves of young macadamia trees planted in new orchards i... more Extensive leaf spot was observed on all leaves of young macadamia trees planted in new orchards in Queensland, Australia. The loss in photosynthetic ability of these trees may contribute to their demise and poor establishment compared to trees without symptoms. A survey of fungal leaf spots on macadamia trees in 20 commercial orchards in Queensland revealed two distinctive types of symptoms. Leaves showing circular dark brown spots with yellow halos (Type 1) and irregular dark brown spots (Type 2) were collected. Fungal isolates associated with the infected leaves were identified by morphological characteristics and DNA sequencing as Neopestalotiopsis clavispora for Type 1 spots and Colletotrichum siamense for Type 2 spots. Koch’s postulates were fulfilled for N. clavispora and C. siamense. Pathogenicity assays showed that both fungi caused severe leaf spots, which are identical to the respective field disease symptoms. In order to clearly characterise them, the two leaf spots were named as Pestalotiopsis leaf spot (Type 1 spots) and Colletotrichum leaf spot (Type 2 spots). This is the first report of N. clavispora and C. siamense causing leaf spots in macadamia in Australia.

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Research paper thumbnail of Evaluation of the effects of an eco-friendly crop protection system on management of whitefly-vectored chilli leaf curl virus disease in Sri Lanka

Phytoparasitica, 2019

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Research paper thumbnail of Plant defense-related enzymes against pathogens: a review

AGRIEAST: Journal of Agricultural Sciences, 2017

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Research paper thumbnail of Exploring the efficacy of silicon supplementation on control of rice grain discoloration disease

AGRIEAST: Journal of Agricultural Sciences, 2019

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Research paper thumbnail of Impacts of climatic parameters and crop management practices on induction of host plant resistance and population dynamics of beneficial insects towards management of viral diseases of chilli and tomato

AGRIEAST: Journal of Agricultural Sciences, 2017

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Research paper thumbnail of Diagnostics of flower blight complex with increasing heterogeneity in macadamia

Phytopathology, 2022

Macadamia is an evergreen tree nut crop cultivated in tropical and frost-free subtropical regions... more Macadamia is an evergreen tree nut crop cultivated in tropical and frost-free subtropical regions worldwide. Flower blight of macadamia is a heterogeneous disease. Currently, the four definitive categories undoubtedly represent only a spectrum of causal pathogens with contrasting lifecycles. Different disease categories seem to result from different types of interaction between organtrophism and environmental factors. Although host genetics influence infection and disease severity, variations in the environment are the most probable explanation for the fluctuating nature of the pathogens and increase in the various types of flower blight. The occurrence of multiple fungal species of Botrytis, Cladosporium, Neopestalotiopsis and Pestalotiopsis highlights the challenges for diagnostics and management. While the efficiency of multi-species qPCR assays relies on species identification, detection at the genuslevel presents a strong modifier that could account for a large proportion of novel species, and also improve characterisation of a range of pathogen subgroups. It appears flower blight causal pathogens are becoming more diverse with time. The qPCR assays developed in this study were used to detect and quantity airborne conidia for each fungal genus associated with flower blight complex in commercial macadamia plantations. The qPCR assays support flower blight risk forecasting and management.

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Research paper thumbnail of Sources, Detection, and Inoculum Quantification of Flower Blight Pathogens in Macadamia

Phytopathology®

Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladospo... more Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladosporium spp., and gray mold caused by Botrytis spp., collectively known as flower blight cause significant yield losses in macadamia. Potential sources of inoculum of the various pathogens in macadamia tree canopy were examined using pathogenicity tests and a multiplex quantitative PCR (qPCR) assay developed in this study. The qPCR assay detected and quantified the relative abundance of the inoculum of flower blight pathogens. The assay revealed that remnant racemes contributed a high amount of inoculum of all the three groups of flower blight pathogens, while the yellow halo leaf spot contributed only Pestalotiopsis/Neopestalotiopsis species. The amount of conidia per gram of remnant racemes ranged from 7 × 103 to 2 × 104 for dry flower disease, 3 × 103 to 1 × 104 for green mold, and 5 to 8 × 103 for gray mold pathogens. Conidia of Pestalotiopsis/Neopestalotiopsis species quantified from l...

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Research paper thumbnail of Etiology of flower blight complex in macadamia

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Research paper thumbnail of Sources and quantification of flower blight pathogens in macadamia

Raceme blights also known as flower blights are used to describe diseases and disorders of macada... more Raceme blights also known as flower blights are used to describe diseases and disorders of macadamia inflorescence worldwide. Flower blights reduce fruit set and control measures are limited. Knowledge of the disease cycle and epidemiological parameters is required. Therefore, the potential sources of inoculum for the three forms of flower blights of macadamia in Australia were investigated. Relative abundance of the inoculum (Ri) in remnant racemes and yellow halo leaf spot in macadamia canopy was quantified and the pathogenicity of the fungal isolates obtained from the plant materials was assessed on developing flowers. Ri >90% was recorded for Neopestalotiopsis species from both the remnant racemes and leaf spot, which indicates the materials are a source of inoculum for dry flower disease. Whereas, Ri <40% was recorded for Botrytis species, the causal agent of grey mould, and Ri = 70% for Cladosporium species, the causal agent of green mould, only from remnant racemes. Con...

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Research paper thumbnail of Biotic risks, pesticide usage and awareness on IPM techniques in paddy cultivation in Polonnaruwa district of Sri Lanka

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Research paper thumbnail of Role of Trichoderma spp. in Biocontrol of Plant Diseases

Microbial Biocontrol: Food Security and Post Harvest Management, 2022

Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a su... more Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a surge. The detrimental impacts of current disease management practices create an urgent need to develop non-chemical and eco-friendly methods. Biological control or biocontrol of phytopathogens is a sustainable and sound approach to overwhelm various threats caused by the existing control measures. Among the biocontrol agents (BCAs), avirulent, filamentous mycoparasitic Trichoderma spp. are well-known for their agricultural application versatility. The host plant-Trichoderma-pathogen interaction plays a pivotal role in plant disease management. Trichoderma spp. network with plant pathogens via direct mechanisms of mycoparasitism, antibiosis and competition while indirectly inducing systemic disease resistance and promoting plant growth and yield when Trichoderma-plant interaction is switched on. The interactions support efficient biological disease control and overall crop recovery from various diseases and ultimately lead to successful crop production. Trichoderma-based BCAs offer significant contributions in the arena of plant protection and disease management. An array of Trichoderma spp. have proven effective against a broad range of plant pathogens by enhancing the plants&#39; overall health and improving their yield. The biocontrol activity, plant-Trichoderma interactions and the efficacy could vary with the type of the pathogens, Trichoderma strain and host plant. Besides, the efficacy and stability of widely used and newly recognized strains of Trichoderma still need to be evaluated under different environmental conditions in the field for successful outcomes.

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Research paper thumbnail of Determination of Pesticide Usage and Its Environmental Impact Quotient in Vegetable Cultivation in Kalpitiya Divisional Secretariat Division of Puttalam District of Sri Lanka

Application of synthetic pesticides has been the main method of controlling pests and diseases in... more Application of synthetic pesticides has been the main method of controlling pests and diseases in crop cultivation. In this context, the objectives of the study were to assess the pesticide usage pattern and determine the environmental impact quotient of pesticide use in vegetable cultivation in Kalpitiya, Sri Lanka. Stratified random sampling method was used to select 100 farmers from Kalpitiya Divisional Secretariat division of Puttalam, which is a predominantly vegetable cultivating area. Pre-tested structured questionnaires were used to collect data during Maha 2016/2017 cropping season. Descriptive statistics and probit model were used to analyze the data. Field Use Environmental Impact Quotient (FEIQ) of pesticides used by the farmers was also determined. The results of the study indicated that the foremost problem in the vegetable cultivation was insect damage (92%) followed by diseases (84%) while weed problem was insignificant. The average extent of cultivation was 2.18 acres where only 14% of respondents’ cultivated land size was greater than 4 acres. Percentage of farmers having more than 5 years of experience in cultivation was 74%. Only 36% of farmers received extension service. Pesticides were applied on vegetable crops by 94% of the farmers. On an average, pesticide application frequency was 4.4, whereas pesticide use (active ingredient) by weight on the vegetable crops was 0.58 kg ha-1. The average FEIQ of pesticide use in the study area was 75.28 ha-1. Probit analysis revealed that educational level, farming experience and access to extension service had a positive and significant (p&lt;0.05) relationship on farmers awareness of risks from pesticide use. Vegetable farmers of this area use extensive amount of pesticides which cause more damage to the environment. Therefore, it is recommended to provide information to the farmers about the judicious use of less toxic pesticides.

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Research paper thumbnail of Study on Risk Identification and Pesticide Usage in Paddy Cultivation in Alayadivembu Divisional Secretariat Division of Ampara District, Sri Lanka

International Conference on Agriculture and Forestry, 2018

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Research paper thumbnail of Evaluation of different casing mixtures for "Makandura White" mushroom production in Sri Lanka

Makandura-White (MK-White) mushroom cultivation requires a special practice, casing. At present, ... more Makandura-White (MK-White) mushroom cultivation requires a special practice, casing. At present, the recommended casing mixture is termite clay, sand, dry cattle manure (3:1:1). However, the availability of termite clay in large quantity is limited. On this background, a study was conducted during June to September 2018 at the Regional Agriculture Research Centre in Makandura, Sri Lanka to find out locally available material that can be easily found and is cost effective for the cultivation of MK-White mushroom. The experiment was arranged in a completely randomized design with seven treatments and three replications. Different combinations of casing mixtures; termite clay, dry cattle manure, dry cannel basin soil, compost and half burnt paddy husk were evaluated for their physico-chemical properties. Further, the effects of casing materials on mycelial growth and pin head formation of MK-White mushroom were determined. There were significant differences (p&lt;0.05) in mycelial growth and pin head formation among the different casing mixtures. The fastest pin head formation and the highest yield of pin heads were recorded in the casing mixture of dry cannel basin soil and compost with a ratio of 3:2. Further, this casing mixture was found to have the optimum level of physico-chemical properties, such as moisture content (44.7%), pH (7.41) and C:N ratio (15:1) to grow MK-White mushroom. Therefore, the casing mixture of termite clay, sand and dry cattle manure which is presently adopted, could be replaced with the readily available dry cannel basin soil: compost (3:2) casing mixture for MK-White mushroom cultivation.

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Research paper thumbnail of Flower blight complex

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Research paper thumbnail of Macadamia integrated disease management (IDM)

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Research paper thumbnail of RNA interference as a promising strategy for plant disease management

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Research paper thumbnail of Leaf spot a possible source of inoculum of dry flower disease in macadamia in Australia

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Recent Advances in Molecular Diagnostics of Fungal Plant Pathogens: A Mini Review

Frontiers in Cellular and Infection Microbiology, 2021

Phytopathogenic fungal species can cause enormous losses in quantity and quality of crop yields a... more Phytopathogenic fungal species can cause enormous losses in quantity and quality of crop yields and this is a major economic issue in the global agricultural sector. Precise and rapid detection and identification of plant infecting fungi are essential to facilitate effective management of disease. DNA-based methods have become popular methods for accurate plant disease diagnostics. Recent developments in standard and variant polymerase chain reaction (PCR) assays including nested, multiplex, quantitative, bio and magnetic-capture hybridization PCR techniques, post and isothermal amplification methods, DNA and RNA based probe development, and next-generation sequencing provide novel tools in molecular diagnostics in fungal detection and differentiation fields. These molecular based detection techniques are effective in detecting symptomatic and asymptomatic diseases of both culturable and unculturable fungal pathogens in sole and co-infections. Even though the molecular diagnostic ap...

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Research paper thumbnail of Management of postharvest anthracnose of banana using inorganic salts alone and in combination with hot water

Plant Pathology & Quarantine, 2020

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Research paper thumbnail of Characterisation of leaf spots caused by Neopestalotiopsis clavispora and Colletotrichum siamense in macadamia in Australia

European Journal of Plant Pathology, 2020

Extensive leaf spot was observed on all leaves of young macadamia trees planted in new orchards i... more Extensive leaf spot was observed on all leaves of young macadamia trees planted in new orchards in Queensland, Australia. The loss in photosynthetic ability of these trees may contribute to their demise and poor establishment compared to trees without symptoms. A survey of fungal leaf spots on macadamia trees in 20 commercial orchards in Queensland revealed two distinctive types of symptoms. Leaves showing circular dark brown spots with yellow halos (Type 1) and irregular dark brown spots (Type 2) were collected. Fungal isolates associated with the infected leaves were identified by morphological characteristics and DNA sequencing as Neopestalotiopsis clavispora for Type 1 spots and Colletotrichum siamense for Type 2 spots. Koch’s postulates were fulfilled for N. clavispora and C. siamense. Pathogenicity assays showed that both fungi caused severe leaf spots, which are identical to the respective field disease symptoms. In order to clearly characterise them, the two leaf spots were named as Pestalotiopsis leaf spot (Type 1 spots) and Colletotrichum leaf spot (Type 2 spots). This is the first report of N. clavispora and C. siamense causing leaf spots in macadamia in Australia.

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Research paper thumbnail of Evaluation of the effects of an eco-friendly crop protection system on management of whitefly-vectored chilli leaf curl virus disease in Sri Lanka

Phytoparasitica, 2019

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Research paper thumbnail of Plant defense-related enzymes against pathogens: a review

AGRIEAST: Journal of Agricultural Sciences, 2017

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Research paper thumbnail of Exploring the efficacy of silicon supplementation on control of rice grain discoloration disease

AGRIEAST: Journal of Agricultural Sciences, 2019

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Research paper thumbnail of Impacts of climatic parameters and crop management practices on induction of host plant resistance and population dynamics of beneficial insects towards management of viral diseases of chilli and tomato

AGRIEAST: Journal of Agricultural Sciences, 2017

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Research paper thumbnail of EFFECT OF CLOROX AS A SEED TREATMENT IN NONFUNGICIDAL APPROACH ON GERMINATION OF CHILLI SEEDS

Proccedings of the 1st National Symposium on Agro-Technology and Rural Sciences - 2020, 2020

Generally seed treatment with a fungicide is a common practice adapted by farmers to control seed... more Generally seed treatment with a fungicide is a common practice adapted by farmers to control seed-borne pathogens for obtaining quality and healthy chilli seedlings. Efforts are underway for obtaining vigorous seedlings with high germination rate. Having this objective in mind, a laboratory experiment was conducted at the to assess the effects of Clorox bleach, an antigerm liquid on germination performance of chilli cv. PC-1. The treatments were arranged in a Completely Randomized Design with three replicates. The Clorox at different concentrations (5%, 10%, 15% and 20%) with different soaking times (20, 30 and 40 minutes) were setup as different treatments and compared with a control treatment of soaking the seeds in sterile distilled water with different soaking times (20, 30 and 40 minutes). The seed germination performances were recorded after 14 days of seeding. Results revealed that 70% seed germination at 14 days after seeding was obtained in application of 5% Clorox solution with 40 minutes soaking time. Further, number of days taken to germinate 50% of seeds was approximately 10 days in the same treatment which was comparably lower than that of the controls. Therefore, it could be concluded that soaking of seeds in Clorox solution at 5% concentration for 40 minutes could be used to achieve better seed germination of chilli.

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Research paper thumbnail of BIOTIC RISKS, PESTICIDE USAGE AND AWARENESS ON IPM TECHNIQUES IN PADDY CULTIVATION IN POLONNARUWA DISTRICT OF SRI LANKA

Proceedings of the 9th YSF symposium 2020, 2020

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Research paper thumbnail of Leaf spot a possible source of inoculum of dry flower disease in macadamia in Australia

Australasian Plant Pathology Society Conference 2019, 2019

Macadamia nut is cultivated commercially in frost-free tropical and subtropical regions worldwide... more Macadamia nut is cultivated commercially in frost-free tropical and subtropical regions worldwide. In Australia, dry flower caused by Pestalotiopsis macadamiae and Neopestalotiopsis macadamiae is one of the biotic constraints leading to significant yield loss in macadamia. Information on dry flower disease cycle and epidemiology is limited. Leaf spot caused by Pestalotiopsis has been reported in macadamia overseas, however, its role as a possible source of inoculum of the dry flower is not known. Preliminary survey of fungal leaf spots on macadamia trees showed two distinct symptoms. Leaves showing circular dark brown spots with yellow halos (type1) and irregular dark brown spots (type 2) were collected from macadamia orchards in Queensland. Fungal isolates were obtained from 20 infected leaves and were identified by morphology and DNA sequencing as Pestalotiopsis spp. for type 1 spots and Colletotrichum sp. for type 2 spots. To conduct a pathogenicity test, conidia suspension (106 conidia/mL) was prepared and sprayed onto 10 healthy leaves of a macadamia potted plant, whereas the control was treated with sterile water. The inoculated plants were kept in plastic bags at high relative humidity overnight and thereafter they were incubated on a bench in a shade house at ~28°C. The pathogenicity tests were repeated three times. Leaf spots similar to the respective field disease symptoms were observed on the inoculated leaves for both type 1 and type 2 spots after 7 days, whereas no visible symptoms appeared on the control leaves. Koch’s postulates were fulfilled for the Pestalotiopsis and Colletotrichum species. Hence, the two leaf spots were distinguished as Pestalotiopsis leaf spot (type 1 spots) and Colletotrichum leaf spot (type 2 spots). This results suggest
that Pestalotiopsis leaf spot could act as a source of inoculum of dry flower during flowering stage in macadamia.

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Research paper thumbnail of Role of Trichoderma spp. in Biocontrol of Plant Diseases

Microbial Biocontrol: Food Security and Post Harvest Management, 2022

Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a su... more Crop losses incurred by major plant pathogens, fungi, bacteria, nematodes and viruses are in a surge. The detrimental impacts of current disease management practices create an urgent need to develop non-chemical and eco-friendly methods. Biological control or biocontrol of phytopathogens is a sustainable and sound approach to overwhelm various threats caused by the existing control measures. Among the biocontrol agents (BCAs), avirulent, filamentous mycoparasitic Trichoderma spp. are well-known for their agricultural application versatility. The host plant-Trichoderma-pathogen interaction plays a pivotal role in plant disease management. Trichoderma spp. network with plant pathogens via direct mechanisms of mycoparasitism, antibiosis and competition while indirectly inducing systemic disease resistance and promoting plant growth and yield when Trichoderma-plant interaction is switched on. The interactions support efficient biological disease control and overall crop recovery from various diseases and ultimately lead to successful crop production. Trichoderma-based BCAs offer significant contributions in the arena of plant protection and disease management. An array of Trichoderma spp. have proven effective against a broad range of plant pathogens by enhancing the plants' overall health and improving their yield. The biocontrol activity, plant-Trichoderma interactions and the efficacy could vary with the type of the pathogens, Trichoderma strain and host plant. Besides, the efficacy and stability of widely used and newly recognized strains of Trichoderma still need to be evaluated under different environmental conditions in the field for successful outcomes.

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Research paper thumbnail of RNA interference as a promising strategy for plant disease management

Food security and plant disease management, 2020

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