Commelina benghalensis harbors Corynespora cassiicola, the tomato target spot pathogen

Abstract

This study elucidates the causative agent of a leaf spot in Commelina benghalensis, grown nearby a tomato field, through a polyphasic approach. Pathogenicity of the causative agent to C. benghalensis and cross infectivity to tomato was performed. Morphological, cultural, and molecular characterization identified the fungal isolate as Corynespora cassiicola. C. cassiicola CB005 produced leaf spot symptoms to C. benghalensis and tomato in all three independent trials. The same fungus was reisolated from the inoculated leaves and thus, confirming Koch’s postulate. Together, C. cassiicola was identified as the causative agent of a leaf spot in C. benghalensis, which is the first record from the Philippines, and was pathogenic to tomato. The fungus’ survival in C. benghalensis, an invasive weed, poses a problem to nearby crops on the next cropping season. Hence, the removal of this weed is important in reducing the source of inoculum in the field. It would be worthwhile to further study other potential plant hosts of C. benghalensis in the Philippines and select for resistance to target leaf spot in tomato cultivars and breeding lines.