Abstract :
Many countries have developed noxious or invasive species lists of plants that are economically or ecologically damaging to both agricultural and environmental areas. These lists, however, rarely include species not yet present in the region, but with the potential to cause significant harm. The challenge in many prevention programs is to anticipate what new weeds are likely to invade a region or country, how to assess their potential impact, what areas provide suitable habitat under current and predicted climate change scenarios, where is their most probably pathway of entry, and how to prevent their introduction and establish. It is far easier for countries or regions to determine potentially harmful weeds by comparing and evaluating weedy and invasive species in other regions of the world with similar climates. This can include plant species that have been problematic for several years and are globally widespread, or plants that are newly established in only one region of the world. A far more difficult task, however, is to determine the potential weedy species that have yet to become problematic in any area of the world. In this paper, I initially compare the weedy and invasive species in Australia and California and then outline a process for determining new potentially invasive species and preventing their possible entry into a region.
