Hundreds of pond apple trees have been removed from the edge of the picturesque Russell River.

Indigenous rangers are targeting the pest species, which was originally introduced as grafting stock for commercial custard apples. It’s now out-competing native species along waterways and in world-heritage rainforests.

Jaragun Ecoservices’ team has treated more than 400 mature trees over a six-month period, along with pond apple seedlings. They reached the areas by boat, to inject trees with targeted dry herbicide capsules.

Pond apple removal work was part of a broader ‘Forest Resilience’ project to better protect six forest types across the Wet Tropics region through weed and pest control, tree-planting and conservation agreements.

Important area with unique microclimates

Terrain NRM’s Deb Bass said the Russell River is an important area.

“Along the lower Russell River, there is lowland rainforest, littoral rainforest and mangroves growing side by side, creating unique microclimates for rare and ancient plants,’’ she said.

“Both littoral and lowland rainforest are listed as Threatened Ecological Communities.”

Cyclones creating opportunities for pest plants

Pond apple got a foothold in the lower Russell River area after Cyclone Larry, when tree canopies were damaged, letting more light in. The project is focused on removing pond apple trees before they create thickets and take over rainforest areas.

“Left untreated, this invasive species will grow into dense thickets. It hasn’t taken over the rainforest yet, so it makes sense to remove the individual mature pond apple trees now.”

Ongoing monitoring for pond apple is needed

Pond apple seeds can remain viable for up to two years. Jaragun Ecoservices rangers will continue to monitor the river system.