Bio inhibitory potential of Clidemia hirta and Mikania micrantha on selected postharvest fungal pathogens and weed seed germination

Abstract

Botanical biocides are a trending sustainable strategy for agricultural pest and disease management. This study was focused on the bio inhibitory ability of two noxious invasive plant species in Sri Lanka; Mikania micrantha and Clidemia hirta. Air-dried plant materials were extracted into 50% dichloromethane/methanol using the bottle extraction method. Antifungal activity of the two extracts was tested against four postharvest fungal pathogens: Cladosporium cladosporioides, Colletotrichum musae, Fusarium sp., and Aspergillus niger. Disc diffusion method (2 mg of extract/disc) was used with negative (50% dichloromethane/methanol) and positive (Mancozeb® and Propineb) controls for screening the antifungal activity. The herbicidal potential of the two extracts at different concentrations (0, 250, 500, 1000, and 2000 ppm) was evaluated using seed germination assay against three common weeds; Pennisetum polystachion, Tridax procumbens, and Ludwijia perennis. M. micrantha extract (2 mg) showed antifungal activity against C. musae and Fusarium sp. while A. niger and C. cladosporioides were insensitive to both plant extracts. C. hirta extract was not effective against the selected fungal pathogens. All three test species were non-dormant with germination percentage >70%. Seed germination of P. polystachion and T. procumbens was reduced to <7% by 1000 ppm C. hirta extract. Two thousand ppm extract of M. micrantha significantly reduced seed germination of T. procumbens and P. polystachion to 23% and 6%, respectively. . Seed germination of L. perennis was not significantly affected by either extract. The early seedling growth of the three weed species was affected by all four concentrations of the two plant extracts. In-general, 1000 ppm extracts of C. hirta and M. micrantha were effective in significantly reducing shoot and root lengths of all three weed species. Hence, the plant extracts of M. micrantha and C. hirta can be used as a potential eco-friendly solution in controlling the tested fungal and weed species.