Pond apple survey work

The search is on for pond apple in the Murray Upper region south of Tully, where aerial surveys will begin in coming weeks.

Terrain NRM’s Deb Bass says drones will be used along waterways and wetlands in the Tully-Murray flood plain area to discover the extent of pond apple and other invasive weeds.

Pond apple is a major environmental weed in the Wet Tropics region and the Murray River catchment is the most southerly part of the region with major outbreaks. It grows in thickets and can replace whole ecosystems.

“We want to prevent its spread,’’ Deb said. “The seeds stay viable for two years. But by removing mature trees from the upper catchment, and continuing monitoring for seedlings, we have a good chance of removing the seed bed.

“Isolated pond apple trees have been found further south in the Lower Herbert but ongoing weed control by the Hinchinbrook Shire Council has prevented any spreading.”

Terrain NRM is working with the Department of Agriculture and Fisheries on a pilot study, and with landholders, Canegrowers Tully, Sugar Research Australia, Cassowary Coast Regional Council, Biosecurity Queensland, the Department of Resources and the Queensland Parks and Wildlife Service.

Deb said drones surveying would only be over wetlands.

“The last catchment-wide survey for pond apple was in 2008. Pond apple now covers 2000 hectares in the Wet Tropics region and it’s spreading in floods when seed and fruit travel downstream. The seeds are also spread via feral pigs.”

The upcoming survey work follows on from pond apple control work as part of Terrain NRM’s ‘Fish Homes and Highways’ project. More than 20,000 mature pond apple trees in the Upper Warrami and Corduroy Creek wetland areas were removed in 2021 and 2022 and there was follow-up work last year to remove seedlings at the same sites. In the process, larger patches of pond apple were found in wetlands.

Deb said survey results would be used to source funding and plan future whole-of-catchment weed control work. The focus area is from the Bruce Highway west to the foothills of the Upper Murray River catchment.