Insecticide reductions in Tully

A collaborative working relationship involving industry and science has led to reduced insecticide use in the Tully catchment through an industry-led extension program. As a result, catchment water quality monitoring data has shown observable and immediate improvements in water quality.

Tully Sugar Limited worked collaboratively with scientists from the Great Barrier Reef Catchment Monitoring Program to monitor pesticides in the Tully catchment. Through communication and engagement with industry and landholders, scientists showed that concentrations of imidacloprid (an insecticide and important management tool for controlling the greyback canegrub and other insect pests) had been increasing over many years.

In the 2016-2017 wet season there was a spike in concentrations. Approximately 30% of water samples collected exceeded the proposed imidacloprid guideline value set to protect freshwater ecosystems (Figure 1). These concentrations also accounted for almost 50% of the ‘total pesticide risk’ in the Tully River.

Figure 1. Imidacloprid concentrations measured in water collected from the Tully River at Euramo during wet seasons between 2015 and 2020. Dots above the black dotted line indicate imidacloprid concentrations that exceed the proposed water quality guideline for protecting freshwater ecosystems (95% species protection).

Concerned about the increased risk to aquatic ecosystems and the stewardship of long-term cane grub management, Tully Sugar Limited in association with Sugar Research Australia and Tully Cane Productivity Services developed a proactive landholder extension program in 2017.

The extension program focused on reducing inadvertent use of imidacloprid for Pachymetra root rot; a soil disease that has similar effects as cane grubs in the Wet Tropics. Other activities helping to reduce imidacloprid run-off included education on the appropriate use of imidacloprid for cane grub management and better detection of Pachymetra root rot, fast tracking the uptake of root rot resistant sugarcane varieties, and research trials (led by Tully Sugar Limited) examining the benefits of burial application of imidacloprid.

As a result, water quality monitoring showed that less than five percent of imidacloprid concentrations detected in the 2019-2020 wet season exceeded the proposed guideline value (Figure 1). The contribution that imidacloprid made to pesticide toxicity risk reduced to approximately 25% and toxicity risk was the lowest recorded since monitoring began in 2016.

These great results have been achieved through a positive working relationship involving Tully Sugar Limited, Tully Cane Productivity Services and the Catchment Monitoring team.

This project was funded by Tully Sugar Limited and Tully Cane Productivity Services with the water quality monitoring funded by Queensland Government as part of the Paddock to Reef Integrated Monitoring, Modelling and Reporting Program.