Isolation and characterization of Colletotrichum gloeosporioides species complex causing chili anthracnose in Lao Cai province, Viet Nam and evaluation of antifungal activity of selected local plant extracts
This study aimed to investigate the occurrence of chili anthracnose, characterize the associated pathogen, and evaluate the antifungal potential of plant-derived products as sustainable management options in the Muong Khuong area, Lao Cai province. Field investigations showed that anthracnose was prevalent on both hot chili and sweet chili, with disease incidences of 50.50% and 70.48%, respectively, during the July survey. Anthracnose symptoms were observed on leaves and fruits of chili types. The pathogen was isolated from symptomatic tissues and characterized based on colony morphology, microscopic features, pathogenicity tests, and ITS sequence analysis. Re-inoculation on detached chili leaves and fruits reproduced anthracnose symptoms, confirming the pathogenicity of the isolate. BLASTn analysis of the ITS region revealed 100% sequence identity with species within the Colletotrichum gloeosporioides species complex. In vitro antifungal assays demonstrated that extracts from Piper betle, Elsholtzia ciliata, and Ocimum basilicum inhibited the pathogen's mycelial growth. Among them, Piper betle showed the strongest inhibitory effect (62.16% inhibition at 5 days after treatment), followed by Elsholtzia ciliata (23.91% inhibition at 5 days after treatment) and Ocimum basilicum (15.68% inhibition at 3 days after treatment). These findings support the potential use of plant-derived products for sustainable management of chili anthracnose.