Providing evidence to improve practice

Individual study: Estimating the minimum salinity level for the control of New Zealand Pygmyweed Crassula helmsii in brackish water habitats

Published source details

Dean C., Day J., Gozlan R.E., Green I., Yates B. & Diaz A. (2013) Estimating the minimum salinity level for the control of New Zealand Pygmyweed Crassula helmsii in brackish water habitats. Conservation Evidence, 10, 89-92


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Crassula helmsii: Use salt water to kill plants Control of Freshwater Invasive Species

A replicated, controlled study in containers in 2011 in Dorset, UK (Dean et al. 2013) found that increased water salinity led to decreased growth rate in C. helmsii. C. helmsii growth rates were highest in the freshwater control (0.05 g/day), and declined as the salinity of the water increased (0.015 g/day in 2 parts per thousand, 0.005 g/day in 4 ppt and a loss of 0.010 g/day in 8 ppt). After 31 days C. helmsii in the 8 ppt salinity treatment had died. Nutrient concentration did not affect growth rate. Ten gram samples of C. helmsii were grown outdoors in 5 l plastic containers in September-October and sampled after 31 days. Three salinities and a freshwater control were tested at three different nutrient concentrations, and each treatment combination was replicated four times.