History and management - Australia and Pacific.

Abstract Parthenium weed (Parthenium hysterophorus) is now recognized as a major invasive weed worldwide. Yet in the 1950s, when it was first discovered in Australia, it was an almost unknown plant. International research on parthenium weed did not start until the 1970s, after reports of increasing health problems caused by the dense infestations in central India. Australian policy makers in 1973-75 were therefore working in an information vacuum when trying to manage this new weed, which was rapidly spreading south from the northern cattle zone. Their response was to establish one of the largest long-term and well-funded weed management programmes ever seen against a single weed, and the outcome has been startlingly successful. This chapter outlines the history and background of parthenium in Australia and the management tools used to produce this success. It shows that the management programme in place from 1975 to the present day, along with the simultaneous development of on-ground methods to reduce spread and a well-funded biological control programme to reduce the impact of existing infestations, has proved highly effective. Parthenium weed is no longer a major threat to farmers and landholders in Australia, and no longer rates as one of the top weeds, even in the worst-affected areas.