Management of Brazilian Joyweed (Alternanthera brasiliana) in the Casuarina Coastal Reserve, Darwin, Australia

Abstract

For the past 20 years, the only locality in the Darwin region in which Brazilian Joyweed (Alternanthera brasiliana) has been recorded outside cultivation is the Casuarina Coastal Reserve. This article documents its recent proliferation as 'spot fires' in disturbed and undisturbed woodland habitats in the central western section of the Coastal Reserve, as well as its spread to woodland at Charles Darwin University's Brinkin campus on the southern extremity of the Coastal Reserve. Both are probably marginal or sub-optimal locations in terms of the species' full range of habitats. This article also profiles Brazilian Joyweed's identifying characteristics and ecology, in particular those aspects that make it an opportunistic invader, and management options in the Coastal Reserve. There, Brazilian Joyweed is spreading, outcompeting native species thereby threatening the ecosystem, and contravening the visual aesthetics of the Reserve. Brazilian Joyweed causes dermatitis and asthma in some people, and is not consumed by - that is, not controlled by - any vertebrate or invertebrate herbivore. These undesirable characteristics, when taken together, render its eradication in the Coastal Reserve and the University campus highly desirable. The populations in both localities should be, and indeed can successfully be, eliminated at the present time. However, the more wet seasons these populations remain unchecked, the harder eradication will become.