Herbicide trials for Cabomba caroliniana in New Zealand
Cabomba caroliniana (Cabombaceae: EPPO List of Invasive Alien Plants) is an obligate submersed macrophyte native to South America. It is a perennial species and primarily reproduces by vegetative fragmentation. The species, commonly known as fanwort, has been traded as an aquarium plant and is naturalised in several regions globally (Asia, Europe, North America and Oceania). In the EPPO region the species is established in Austria, France, Germany, Hungary, the Netherlands and the United Kingdom (England). In the EU, the species is listed as a species of Union concern (Regulation (EU) 1143/2014). In New Zealand, C. caroliniana has been cultivated as an aquarium plant for at least 30 years and around the late 2000s it became established. In New Zealand, herbicide trials on the species were conducted in contained conditions using the following herbicides: carfentrazone, endothall, flumioxazin, and triclopyr. All four herbicides were shown to reduce fanwort biomass though viable plant material remained following the application of all herbicides. This indicates that there is the potential for rapid regrowth following treatment, and there is a high degree of uncertainty of the outcome where the herbicides are to be used for the management of field populations. The current study highlights that none of the herbicides are recommended for use in eradication programs against C. caroliniana without a clear understanding that multiple applications will likely be required, and there is a degree of uncertainty regarding the level of efficacy that can be achieved.
Hofstra DE, Clements D, Rendle DM, Champion PD (2021) Response of fanwort (Cabomba caroliniana) to selected aquatic herbicides in New Zealand. Journal of Aquatic Plant Management 59, 35-39.