Saman Abeysinghe

University of Ruhuna · Botany

Microorganisms inhabiting soil/plant systems produce antimicrobial compounds including secondary metabolites (SMs). They are low-molecular-weight structurally diverse and complex compounds that are not essential in their life unless they meet undesirable conditions. SMs such as antibiotics, toxins, ribosomal peptides (RPs), low-molecular-weight vol...

Sri Lanka is a tropical country equally having rich diversity of arthropods including natural enemies, economic pests, and indigenous plants majority with unique chemical properties. Because of the substantial losses due to pests and diseases, plant protection remains an essential issue in agriculture production in the country. There is increasing...

Phytoplasmas that infect gramineous plants, including Napier grass stunt, sugarcane whiteleaf, sugarcane grassy shoot, and Bermuda grass whiteleaf, have been classified into two closely related groups, 16SrXI and 16SrXIV, based on the 16S ribosomal RNA (rRNA) gene. Subsequently, phytoplasmas associated with coconut and Areca palm in southern India...

Papaya ( Carica papaya) is a very popular fruit crop in Sri Lanka, grown as a home garden and commercial crop for local and export markets. Papaya is commercially cultivated in Sri Lanka in about 8,000 ha with production of about 32,000 …

Root rot, caused by Fusarium solani f. sp. phaseoli, is one of the main root diseases impacting production of common bean in Sri Lanka. Rhizobacteria were screened in dual Petri plate assays to select antagonistic strains against F. solani f. sp. phaseoli. B. subtilis CA32 effectively antagonized the pathogen. T. harzianum RU01 also showed the anta...

Phytoplasmas are responsible for a range of diseases in the Gramineae in Sub-Saharan Africa and Asia including sugarcane grassy shoot (white leaf), rice yellow dwarf, napier grass stunt and Bermuda grass white leaf. In previous work, we have designed uni-versal nested PCR primers based on the secA gene for amplification of DNA from phytoplasmas in...

A combination of two compatible biological control agents, Bacillus subtilis CA32 and Trichoderma harzianum RU01, both antagonistic to the pathogen Rhizoctonia solani , was used to control damping-off in Solanum melongena and Capsicum annuum. Radial growth of the mycelium of R. solani was inhibited by T. harzianum RU01 in dual Petri plate assay. T...

Bean rust caused by Uromyces appendiculatus Pers., is one of the major foliar diseases in bean (Phaseolus vulgaris L.) worldwide, which leads to considerable crop loss. Selected fluorescent rhizobacteria were screened for their ability to trigger induced systemic resistance (ISR) against rust in beans under greenhouse and field conditions. Rhizobac...

Sclerotium rolfsii Sacc. the causal agent of collar and root rot of chili (Capsicum annuum L.), is one of the most important soil-borne pathogens in Sri Lanka. Bacillus subtilis CA32r, a stable spontaneous kanamycin resistant isolate, showing antagonism in a Petri plate assay, was selected for greenhouse pot experiments to control S. rolfsii. An et...

Trichoderma spp. are effective biocontrol agents for a number of soil-borne plant pathogens. Some isolates are also known for their ability to induce systemic resistance in plants against different foliar pathogens. Induction of systemic resistance against Uromyces appendiculatus, the causal agent of bean rust, by Trichoderma spp. has not been repo...

Rhizobacteria Pseudomonas fluorescens CA05, Pseudomonas putida CA28 and Bacillus subtillis CA32 which showed antagonism in a Petri plate assay were tested singly and in combination for their biological control efficacy against Rhizoctonia solani and Sclerotium rolfsii under greenhouse conditions. The bacteria were applied to the seeds before seedin...

In this study, only non-antagonistic, root-colonizing bacterial isolates and non-pathogenic F. oxysporum isolates were evaluated either alone or in combination as biological control agents. Two non-pathogenic F. oxysporum isolates significantly reduced the Fusarium root and stem rot severity compared to the pathogen inoculated controls plants. Alth...

The aim of this study was to evaluate the ability of non-pathogenic F. oxysporum isolates from suppressive soil in Sri Lanka to control Fusarium root and stem rot of Cucumis sativus L. (cucumber) under greenhouse conditions. Three non-pathogenic F. oxysporum isolates were included in the study. Fusarium isolates were first checked in vitro for path...