Crassula helmsii is an invasive water weed that dominates still or slow-flowing water bodies. It’s spreading throughout the UK and has the potential to out-compete native flora and reduce oxygen levels by forming dense mats. Management of this species can be very challenging, with chemical and mechanical options limited. CABI were commissioned by the UK government to investigate the possibility of controlling the weed using biological control. This includes testing by our scientists to ensure that any potential agent is safe for release.