Journal of Agricultural, Life and Environmental Sciences ISSN:2233-8322(Print) 2508-870X(Online) 농업생명환경연구

As more people have begun paying attention to eating healthy, the value of vegetable crops such as Chwinamul, is increasing. However, various plant pathogenic fungi cause serious economic losses during the production of Chwinamul but relevant research remains insufficient. In this study, the pathogens responsible for causing leaf spot disease in two cultivars of Chwinamul, Aster scaber, and Ligularia fischer, were isolated and analyzed using the 18S rRNA internal transcribed spacer (ITS) and RNA polymerase II subunit 2 (RPB2) regions to identify the causal pathogens. Two fungal species, Alternaria alternata and Phoma sp., were identified. Based on the abundant isolation of A. alternata from infected tissues of Chwinamul, we re-inoculated A. alternata on A. scaber and confirmed that the pathogen was the main causal agent of leaf spot disease. Metconazole was the most effective fungicide to control A. alternata, showing 100% inhibition of mycelial growth at a concentration of 100 µg/mL. Difenoconazole and cyprodinil were also highly effective with 83.1% and 85.5% inhibition of mycelial growth, respectively, at a concentration of 1,000 µg/mL each. Streptomycin was the least effective, with only 25.3% inhibition at a concentration of 1,000 µg/mL. Our study provides information on the causative agent (A. alternata) of leaf spot disease in Chwinamul and suggests an effective fungicide to combat A. alternata.