17 July 2008

3 minute read

Oceania

Bellyache bush is responsible for infesting productive grazing land, killing livestock and reducing biodiversity and has potential to spread across Australia´s entire tropical savannas.

To develop effective control options for the weed, the Department of Primary Industries and Fisheries´ (DPI&F) Tropical Weeds Research Centre has been studying its ecology and management for the past six years.

These researchers have found an integrated management approach is necessary to control weed areas, which can spread up to 75% over three years - even with below average rainfall.

Economic impacts

Bellyache bush is toxic to animals and has killed cattle, horses and goats in Queensland.

DPI&F weed scientist Dr Faiz Bebawi said cattle tended to eat the bush in drought years and this resulted in direct stock losses for pastoralists.

He said because the weed aggressively spread into impenetrable clusters that wiped out native grasses, it also meant significant loss of productive grazing land.

"And it increases mustering costs because the multi-stemmed, sticky-leaf nature of the bush means horses have difficulty getting through it," he said.

Management

Dr Bebawi said graziers in susceptible areas who did not have bellyache bush on their properties should maintain a vigilant watch for any plants, especially along creek lines or flood-prone areas. Any plants found should be removed quickly.

He said researchers had found bellyache bush was a vigorous plant that set seed within 55 days under ideal conditions, which meant it had to be wiped out in this period to prevent seed going into the seed bank.

For small patches of the weed, hand pulling or spot spraying with selective herbicides were recommended.

Dr Bebawi said researchers had found integrated control measures using fire, machinery and herbicides over a 4-6 year period were effective in controlling big, established infestations of bellyache bush.

"If you only carry out one of these control measures in a single year, it actually aggravates the problem," he said.

"But we have found that four years of integrated control methods will significantly deplete its seed bank."

Bellyache bush is very sensitive to fire and burning is most effective if pastures are spelt beforehand to ensure a good fuel load.

Slashing as close to ground level as possible, using heavy duty slashers or mulchers has also been successful in suitable areas. This is best done when the plant is actively growing - during or soon after the wet season.

There are two selective herbicides currently registered for bellyache bush - commonly sold as Brush Off or Starane or related generic brands - and they do not affect surrounding grass.

Dr Bebawi said landholders appear to get mixed results with these herbicides at times, but generally if one doesn´t work well in their situation the other will.

"For bellyache bush it is extremely important to wet the plants well and to make sure that a wetting agent is used," he said.

Dr Bebawi said research into biological control of bellyache bush had not yet found any successful agents, but this work was continuing with additional funding from Meat and Livestock Australia. One agent is currently in quarantine at the DPI&F´s Alan Fletcher Research Station in Brisbane undergoing host testing.

He said graziers were having success with establishment of healthy pasture to out-compete bellyache bush.

"For example, we have seen areas in the tropics where buffel grass has replaced bellyache bush when conservatively grazed to enable it to maintain its competitiveness," he said.

TheCattleSite News Desk