Weeding out Gamba a win during the wet

Improved treatment knowledge, reduced density and revegetation success were among the positive results of the annual Gamba Grass Taskforce weed eradication program held in the Cook Shire last week. 

More than 40 landholdings were treated for Gamba grass (Andropogon gayanus) during a three-day break in heavy rain.

“Miraculously, spraying was unhindered by weather mid-week - on Monday and Friday it rained incessantly. However, there were 12 separate vehicle recoveries due to boggy conditions,” Darryn Higgins, Cook Shire’s Biosecurity and Local Laws Manager, said.

Nine taskforce teams descended on Cooktown to carry out the annual eradication, which aims to wipe out the invasive plant restricted under the Biosecurity Act 2014. 

Created in 2021, the Taskforce pools shire council resources from as far south as Hinchinbrook to form a convoy of vehicles to tackle weed spraying in key areas around the Cooktown region. 

Cape York NRM  provides logistical support, including meals and accommodation for taskforce visitors to Cooktown. 

The program’s success continues to grow, with more teams attending from the Far North Queensland Regional Organisation of Councils (FNQROC) - including Hinchinbrook, Cook, Mareeba, Douglas and the Tableland shires - and crews from the Queensland Department of Resources, Queensland Parks and Wildlife Service, Jabalbina Rangers and Melsonby Rangers.

As Darryn has said,  combining resources is a win-win for the shires as a cost-effective way to tackle a regional problem. 

This year’s good news revealed the heavy flooding that hit the region following Cyclone Jasper had not triggered increased growth and spread of the weed.

“In fact, there has been a measurable reduction in the density of gamba grass in target areas,” Darryn said. 

The annual visits are also an established event, with weed awareness and treatment methods garnering community support.

“Some properties have transitioned to private management of the species as it is now within the capacity of individual landholders, which is great news,” Darryn said. 

“We want to continue to foster this transition across additional properties.”

Another exciting development was the results of trial revegetation plots. 

“These were established in treated [Gamba grass] areas with a combination of humidicola grass (Brachiaria Humidicola)and signal grass (Urochloa decumbens), and have been successful. We intend to expand this strategy to larger areas this year.”

A post-taskforce survey will be conducted later in the year to gather more data on taskforce impacts.

The taskforce focuses on the Annan/Endeavour catchment, adjoining sections of the Jeannie and Normanby catchments and in the south around Mungumby Creek.

• Gamba grass (Andropogon gayanus) is fast growing and can overrun local ecosystems,  impact on nutrient and water availability in the soil, and fuel fires with intensities well above that posed by native vegetation.
• It was originally introduced from tropical Africa and is spread by seeds dispersed by wind or water, and from mud attached to vehicles and machinery.