Solidago canadensis L. extracts to control algal (Microcystis) blooms in ponds

Landscape ponds often suffer from the overgrowth of nuisance algae (including cyanobacteria). The use of Solidago canadensis L. as an algicide in a natural water column was evaluated in this study. The results show that when S. canadensis L. extracts were added to the outdoor enclosures, Microcystis biomass decreased by more than 70% after 5 d and more than 80% after 25 d. The initial negative effects of the extracts on the water quality were not long-lasting. In addition, the extracts had lower toxicity to Daphnia magna and zebrafish than to Microcystis aeruginosa. In conclusion, S. canadensis extracts effectively controlled Microcystis growth in a natural water column, and it is reasonable to expect that the extracts have fewer adverse effects on the aquatic ecosystem. This study suggests that using this plant as an algicide to control Microcystis blooms in landscape ponds is feasible.