Identification of suitable potential pathogens for biocontrol of water hyacinth

Abstract

Water hyacinth is one of the most noxious invasive aquatic weed in Sri Lanka.A survey of plant pathogenic fungi associated with naturally infected water hyacinth (Eichhornia crassipes) was conducted in different waterways in the Eastern part of Sri Lanka. Four fungi Alternaria alternata, Cercospora rodmanii, Aspergillus sp.and Trichoderma sp were isolated and confirmedtheir pathogenicity at laboratory. The leaf area affected by the fungal pathogen changes with the intensity (days). The changes in leaf area affected by the pathogen across intensity levels depend upon inoculation method (p=0.003). But there was no statistically significant effect in the inoculation methods on the leaf area affected by the fungal type (p=0.06). All fungal types had different levels of dead lesions formed in water hyacinth. After seven days of inoculation, Alternaria sp. revealed to have the highest affected area, followed by Aspergillus sp. and Cercospora sp but, the Bonferroni mean separation revealed that all four fungal species had similar level of effects in term of dead lesion formed in leaves after 22 days of inoculation. The study suggests that, all the isolated pathogens had potential to control water hyacinth, but the Alternaria alternate was found to be better virulence candidate under laboratory conditions. It may be a potential biocontrol agent against water hyacinth and further studies on performance evaluation under natural environmental conditions and their host specificity test are needed