HHERBICIDE spread by drone technology may soon become a standard method of controlling mimosa bush, a woody weed challenge in North West NSW thanks to a trial currently being undertaken by NSW North West Local Land Services on Travelling Stock Reserves.

Dense thickets of mimosa bush have long been an unwanted feature of the landscape around Moree and Warialda due to the invasive thorny shrub rendering large areas of land unproductive, but the shrub also harbours other invasive weeds such as Harissia cactus and tiger pear.

Thriving in tropical, sub-tropical and warm temperate climates, mimosa has large thorns and can grow up to six metres in height. Labour intensive treatment methods have previously included fire, mechanical removal and on ground chemical control.

Determined to find a more efficient solution, North West Local Land Services undertook a trial using drone technology to apply herbicide in pellet form on Travelling Stock Reserves in the Moree, Garah and Pallamallawa areas.

Four years on, the trial has proved highly successful. When comparing an area treated with mulching only, the drone-spread herbicide combined with post herbicide mulching has resulted in a significant reduction of weed regrowth. Native groundcover is also recovering well despite the area being heavily grazed by livestock throughout the duration of the trial.

TSR Ranger Scott Graham, left, with TSR Team Leader Mal Scott

North West Local Land Services travelling stock reserve ranger Scott Graham said using drones to disperse the herbicide had greatly increased the speed in which large areas of mimosa can be treated. The drone technology is best applied where mimosa has formed a monoculture and generally free of other native woody tree and shrub species.

“Using the drone has meant that we have been able to treat large areas faster, and we’ve avoided the frequent breakdowns of machinery that we had before as this method is much gentler on machinery,” he said.

“The drone has also saved us a considerable amount of manpower, which is important as our small team has 160,000 hectares to manage.”

The team is currently following up any required hand treatment on successfully treated patches and are embarking on new treatment areas.

Mimosa is a listed invasive native species under the NSW Land Management Framework for some of the regions in NSW, and similar legislation in Queensland. Prior to managing the species, landholders are advised to contact the Land Management team at Local Land Services for more information on legislative requirements.

Mimosa woody weed

Source: LSS