Crofton weed biocontrol

Ageratina adenophora Crofton weed Crofton weed is a rapid-spreading weed that is invasive in many areas along the eastern coast of Australia, particularly cleared land that is not grazed (such as public reserves). Crofton weed reduces the carrying capacity of grazing land and restricts movement of stock and machinery. It is unpalatable to cattle, and poisonous to horses. Biological control is believed to be the only viable option to reduce dense infestations of Crofton weed, particularly in areas of mainland Australia and Lord Howe Island that are difficult to access. Three biocontrol agents have been released to control Crofton weed: 1. Crofton weed rust fungus *Baeodromus eupatorii* 2. Crofton weed leaf-spot fungus *Passalora ageratinae* 3. Crofton weed gall fly *Procecidochares utilis* The combined effects of these three biocontrol agents are expected to reduce the growth and spread of the weed in Australia. The most recent agent, the rust fungus, was released in 2015 and 2016 at close to 250 sites in NSW and south-east Queensland. The rust fungus was confirmed as established at 59% of these sites within 6-12 months after releases. To enhance natural spread, community members may consider redistributing the rust fungus to sites where it is absent. Step-by-step guides (see the Resources tab) are available to facilitate releases of the rust fungus and to monitor release sites for establishment and impact of the rust. Once established in an area, rust spores are easily redistributed by wind to nearby Crofton weed infestations, facilitating the spread of this agent. The CSIRO's [Crofton weed research](https://research.csiro.au/crofton-weed/) page provides further information on past research, or check the Blog page for updates on news and events.