Currant bush studies reveals fire is best form of eradication

Currant bush is a widespread problem in north and central Queensland. A 1999 survey described it as the most important weed in the Dalrymple shire with 47 per cent of sites surveyed affected.

The seed is spread by birds when they eat its small edible fruit. Once established, currant bush spreads outwards with the stems laying down and rooting to the ground to form new daughter plants.

It competes strongly with grass for water and nutrients, significantly reducing pasture production if it gets out of control.

Observations from the Department of Agriculture and Fisheries' long-term Wambiana Grazing Trial near Charters Towers show that this can happen quickly if currant bush is not managed.

Observations on currant bush began at the Meat and Livestock Australia funded trial in 1998. While currant bush prefers the box land type (Eucalyptus brownii), it also impacts the brigalow (Acacia harpophylla) landtypes on heavier clays. However, it is far less common on the lighter soils dominated by silver leaf ironbark (Eucalyptus melanophloia).

Despite burning in 1999 and 2011 and two extended drought periods, currant bush canopy cover has more than doubled on the box country, from 13pc in 1999 to more than 30pc in 2020. Currant bush cover has also nearly doubled on the brigalow landtype.

This increase has reduced the area of pasture available and consequently increased the grazing pressure on the remaining pasture. While the increase in currant bush has occurred across all grazing strategies in the trial, the increase is slightly greater in the heavily stocked paddocks.

Findings from the Wambiana trial suggest that the best way to manage currant bush is to stop it from becoming a problem in the first place. This can be done by maintaining a healthy, competitive grass cover and regular burning.

Where it has become a problem, fire is possibly the only economic tool to manage it. However, currant bush recovers relatively quickly after fire so regular burning is needed to keep it in check.

Good grazing management, in particular having the right stocking rate, will maintain a healthy competitive pasture cover and provide the fuel needed for a more regular fire regime. Incorporating wet season spelling, especially after fire, will ensure pasture recovery and help maintain a desirable woody plant/grass balance.

This article was produced by FutureBeef-a collaboration between Meat & Livestock Australia and the Queensland, Northern Territory and Western Australian agriculture departments.