Australia's Botanic Gardens weed risk assessment procedure

J.G. VirtueA,E, R.D. SpencerB, J.E. WeissC,E and S.E. ReichardD

A Department of Water Land and Biodiversity Conservation, GPO Box 2834, Adelaide, South Australia 5001, Australia.

B Royal Botanic Gardens Melbourne, South Yarra, Victoria 3141, Australia.

C Department of Primary Industries, PO Box 48, Frankston, Victoria 3199, Australia.

D College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA.

E Cooperative Research Centre for Australian Weed Management.


The majority of agricultural and environmental weeds in Australia have originated from ornamental horticulture. Botanic gardens require a simple yet robust method for rapidly screening the relative weed risk of taxa in their collections. A ten question, multiple choice, additive weed risk assessment system was developed for application to taxa growing in gardens. The major city botanic gardens in Melbourne, Hobart and Perth used the system to score 100 taxa. Separately, a national survey and a literature review of the same 100 taxa were undertaken to obtain two independent datasets for assessing their level of weediness. Testing of the system showed that it has good discriminatory power and cut-off scores were chosen that have about 80% accuracy for both low weed risk and high weed risk species. There was poorer accuracy to distinguish medium weed risk species. The system has wider potential application for the nursery and garden industry as a tool to help reduce the number of high weed risk ornamental species in cultivation.


Plant Protection Quarterly (2008) 23 (4) 166-178.