Lippia, Phyla canescens, an increasing threat to agriculture and the environment

摘要

Lippia, Phyla canescens (Kunth) Greene is a native forb of South America and is now widely distributed across the world. Lippia is present in all mainland states of Australia, except the Northern Territory. It is often confused with P. nodiflora (L.)Greene, but this species prefers tropical and sub-tropical areas. Lippia is now a major weed of floodplains within the Murray-Darling Basin (MDB). Recent concern about lippia led to the formation of the Murray Darling Lippia Working Group and an assessment of lippia within the MDB that was supported by the MDB Commission. Lippia currently infests 5.3 million ha of the MDB and this is predicted to increase following recent floods. It is estimated to cost the grazing industry 38 million dollar p.a. and have an environmental cost of 1.8 billion dollar p.a. It is a major threat to biodiversity and riparian areas. Current pasture management practices fail to limit the expansion of lippia. Cultivation is useful, but it poses a high erosion risk for floodplains. There are no effective management strategies for lippia in riparian areas. It is essential that research into biological control and other management strategies commence immediately, in conjunction with awareness and education programs, to halt the spread and help manage this very aggressive weed.