Comparing Patersons curse plants from Australia with those found in Spain and Portugal has given researchers from the Graham Centre an understanding of why the weed is such a successful invader.

The research has been presented at the International Society of Allelopathy Eight World Congress in Marseille France by Charles Sturt University (CSU) PhD student Mr Dominik Skoneczny and research associate Dr Xiaocheng Zhu.

Patersons curse is estimated to cost Australian sheep and cattle producers $250 million a year in lost productivity, control and fibre contamination, Mr Skoneczny said. The plant was introduced to Australia in the mid-1800s, she said.

The research collected samples from numerous plant populations from Australia, Portugal and Spain to examine the genetics, ecology and chemistry of Patersons curse in various locations, she said.

In particular I analysed the bioactive secondary compounds produced by the Patersons curse shoots and roots which play a role in plant defence.

I found Patersons curse plants established more densely in Australia and produced up to six fold higher levels of antimicrobial and phytotoxic compounds (naphthoquinones) in their roots.

Mr Skonecznys research is part of a larger Discovery project funded by the Australian Research Council (ARC) and led by CSU Professors Leslie Weston and Geoff Gurr.

This research is significant because its shown that multiple mechanisms, including enhanced genetic diversity, production of root-based defence chemistry, prolific seed dispersal and in some cases a lack of other plant competitors have contributed to the continued spread of this species across 30 million hectares in Australia, Professor Weston said.

In contrast, in its native range in the Iberian Peninsula, the species is often difficult to locate amongst biodiverse flora and is not considered to be a serious pest.