Purpose: In September 2019, a rapidly spreading soft rot disease was observed in an Aloe vera cultivation in Puttlam District, Sri Lanka causing rotting of leaves and whole plant death, within three to five days. Identification of causal pathogen of soft rot was the main objective for effective management of the disease. The aim of this study was to isolate and molecular identification of causal pathogen of soft rot disease of A. vera and to confirm its pathogenicity. Research Method:The causal bacterium was isolated on Nutrient Agar medium and initially identified by colony characters. Pathogenicity was assessed by inoculation of leaves of potted A. vera plants with bacterial suspension of each isolates (x108 cfu ml -1 ). Bacterial DNA was extracted and subjected to PCR, using universal primers 27F and 1492R to amplify 16S rRNA region of the bacterium. The PCR products were sequenced and homology search was performed with GenBank database. Findings: Typical field symptoms began appearing after 24 hrs on inoculated plants, with the death of whole plant within two-three days after inoculation Based on PCR analysis, sequencing and homologysearch results, the causal pathogen of the bacterial soft rot disease of A. vera was identified as Dickeya chrysanthemi (former E. chrysanthemi). Sequences were deposited in GenBank for two bacterial isolates, kb (Accession No.MT028490.1) and kd (Accession No.MT028539.1). A BLAST search revealed 99 % identity with D. chrysanthemi from China (JF779681.1).Originality/Value: To our knowledge, this is the first report of D. chrysanthemi causing bacterial soft rot of A. vera in Sri Lanka. This finding will be very useful to formulating disease management strategies for bacterial soft rot of A. vera and to prevent outbreak of the disease.

Big onion is a main cash crop grown in Sri Lanka. However, the crop is highly susceptible to diseases: anthracnose, purple blotch, bulb rot and black mold. Although black mold disease symptoms are associated with the onion bulb, black moldy growth on onion flowers has been observed to be spreading in Sri Lanka during the last decade resulting in the reduction of quantity and quality of onion seeds. Hence, this study was conducted with the objective of isolation and identification of causal agents of the onion flower mold. Big onion flower samples with mold symptoms were collected during Maha season 2016/17 from the major onion growing areas of Anuradhapura and Matale districts. Four organisms were isolated from onion flower: Aspergillus, Penicillium, Collectrotichum and Altenaria. Out of the four, Aspergillus dominated. Hence, Aspergillus sp. isolated from onion flowers was compared with the causative agent of black mold of onion bulbs. Koch's postulation studies of flower and bulb inoculation with respective Aspergillus isolates resulted the same black color molds in the flower and bulb Inoculation of other fungal isolates did not show the black old symptoms in flower and bulb. PCR amplification with ITS1/ITS4 universal primers confirmed the isolated Aspergillus from flower as well as bulb are to be A. niger. Results confirmed that the onion flower black mould disease is caused by A. niger: the causal organism of onion bulb black mold as well.

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