Weeds in Australia

Managing weeds

Case Study: Eradication of Kochia in Western Australia

Kochia (Bassia scoparia) is a large, fast-growing annual weed of cereal crops and pastures in warmer regions of the world that is also grown as a salt-tolerant forage plant. It was introduced into the Western Australian wheat belt in 1990 as a forage plant and to revegetate salt-affected land, but soon began to spread and become invasive.

Scientific advice was important in defining the threat posed by Kochia, which was rapidly recognised as significant for other wheat-producing areas in Australia with similar climates. Consequently, management of Kochia became a national priority, and in 1992 a combined national/state-funded eradication program commenced.

Fortunately, eradicating Kochia proved to be relatively uncomplicated. The majority of infestations were small and of low density. Furthermore, Kochia was susceptible to control treatments (herbicides, grazing, burning and mechanical removal) and plants ceased to be seen in treated areas two years after treatment began. The last sightings of Kochia in Western Australia were in March 2000.

The Kochia eradication program was exceptional in many respects, with several biological and management aspects working in favour of a successful outcome. These included detailed knowledge of the original introduction sites, early and well-resourced official intervention, the plant's largely conspicuous nature and long vegetative period with limited seed dormancy, and the fact that there were fences around most planting sites, which prevented spread.