Know your enemy: recent records of potentially serious weeds in northern Australia, Papua New Guinea and Papua (Indonesia)

Abstract

Botanical collectors rarely specialise in introduced species. Consequently weeds are usually under-represented in herbaria, and comprehensive current checklists of local and regional weed floras are lacking. Potentially serious new weeds are often overlooked until they are widely naturalised and having a harmful impact on agricultural production or the environment. Weed surveys conducted under the auspices of the Northern Australia Quarantine Strategy (NAQS) have documented additions to the weed flora of northern Australia, Papua New Guinea (PNG), and the Province of Papua (Indonesia). New distribution records for the serious tropical weeds Chromolaena odorata (L.) R.M. King & H. Rob. (Asteraceae), Mikania micrantha Kunth (Asteraceae), Cleome rutidosperma DC. (Capparaceae), Limnocharis flava (L.) Buchenau (Limnocharitaceae), Clidemia hirta (L.) D.Don (Melastomataceae) and Piper aduncum L. (Piperaceae), as well as two previously 'unknown' weeds Chromolaena squalida (DC.) R.M. King & H. Rob. (Asteraceae) and Praxelis clematidea (Griseb.) R.M. King & H.Rob. (Asteraceae) are discussed. Early detection and response to new invaders offers the best opportunity for cost-effective intervention. In PNG and Papua, detection of Chromolaena odorata facilitated expansion of an ACIAR-funded biological control program to include these regions. In north Queensland, infestations of Chromolaena odorata, M. micrantha, L. flava and Clidemia hirta are targets of eradication campaigns. Even though scarce resources and differing priorities prevent responses against every new invader, it is hoped that collection and dissemination of information on the spread of potentially serious weeds will have benefits for the entire region.