Effectiveness of methods to control the invasive non-native pitcherplant Sarracenia purpurea L. on a European mire

Pitcherplant Sarracenia purpurea is a North American carnivorous plant that has become invasive on mires throughout Europe. It appears to have limited dispersal ability and so eradication may be feasible given early detection and effective control. We used a field experiment to assess the effectiveness of three control methods – hand-pulling, spot-spraying with glyphosate, and turf-stripping – on the largest established population of S. purpurea in Great Britain. After one year all three treatments had significantly reduced the abundance and flowering performance of S. purpurea. Turf-stripping was the most effective technique but had the greatest impact on non-target species. Spot-spraying and hand-pulling caused significant reductions in adults with only a small reduction in associated species diversity. However, hand-pulling significantly increased the numbers of seedlings and juveniles due to increased recruitment and competitive release following the removal of adults. Spot-spraying caused some damage to associated species but this was not significant. In conclusion, spot-spraying with glyphosate provides the most cost-effective method for eradicating S. purpurea but needs to be carried out with great care to avoid damaging sensitive mire ecosystems. Hand-pulling offers a more labour intensive alternative but its success will rely on monitoring for at least four years to ensure that the recruitment of juveniles is exhausted. Turf-stripping is unlikely to be an acceptable technique given the global importance of mire ecosystems invaded by S. purpurea in Europe.