English broom, Scotch broom
Broom is highly invasive, and has become an agricultural and environmental weed in many parts of the world. In Australia, broom is designated a [Weed of National Significance](http://weeds.ala.org.au/WoNS/brooms/). Broom dominates natural ecosystems, reduces the abundance of native plants, alters soil characteristics and fire regimes, and restricts access to watercourses.
Broom is an economically important weed on grazing properties, as it invades and out-competes pasture species.
Four biological control agents have been intentionally introduced to Australia:
1. Twig-mining moth *Leucoptera spartifoliella*
2. Broom psyllid *Arytainilla spartiophila*
3. Broom seed beetle *Bruchidius villosus*
4. Broom gall mite *Aceria genistae*
Populations of broom psyllid and twig-mining moth remain low and their impact to date negligible. The seed beetle is well established at several sites, although its impact on seed output is not yet known.
The successful establishment and build-up of damaging gall mite populations at a number of sites across south eastern Australia indicates this agent has considerable potential. Galls reduce plant health and flowering, and ease of collecting and redistributing galls by land managers and community groups will facilitate the spread of this agent across the landscape.
Broom rust *Uromyces pisi-sativi* is an accidental introduction to Australia, however it has spread rapidly and has been implicated in plant death. The contribution of broom rust to the biological control of broom is poorly understood and requires further study.