The Science Behind Surveillance: Understanding TR4 Monitoring on Banana Farms

The Australian Banana Growers’ Council’s surveillance strategy is a proactive approach to monitoring and managing TR4 across commercial banana farms. It’s designed not only to detect the disease but also to track its spread and ensure that growers have the tools they need to mitigate risks. This surveillance effort is structured under the broader TR4 Disease Management Plan, which aims to protect the entire banana industry.

The goal of the surveillance program is twofold: to provide early detection of the disease and to give growers confidence in the status of TR4’s spread. Growers are understandably concerned about the disease, particularly as it has the potential to devastate crops, especially on farms that have weaker biosecurity practices. As such, the ABGC’s surveillance efforts are integral to helping banana growers have confidence in its management.

The Role of Surveillance

Surveillance is a cornerstone of ABGC’s approach to managing TR4. It is carried out by trained ABGC Surveillance Officers (SO’s) who are authorised to identify symptoms of the disease in banana plants. Early detection is key to controlling the disease before it spreads to neighbouring farms or larger regions.

Surveillance is carried out in a familiar manner (as used in previous surveillance) by walking through banana farms and visually inspecting plants for signs of TR4. Approximately 80% of a farm’s plants are inspected, which helps ensure that any disease symptoms are detected early. If a banana farm is not fully developed, surveillance will focus on the perimeter of the farm, providing a comprehensive check for the disease.

Implementation

The key components of the ABGC surveillance strategy and sequence of prioritisation areas for surveillance are:

i                            ABGC surveillance will commence with high-risk properties in the Tully and    Innisfail areas, as identified by a buffer area of 38km radius from known infested properties.

ii                         Other banana farms in the greater Innisfail area will receive surveillance following the completion of the initial priority area (38km buffer)

 iii                       Banana farms in the Tablelands, Mareeba and Lakeland and other remaining areas will be targeted after the greater Innisfail area.

 iv                       Re-commence surveillance in the Tully-Innisfail buffer area upon completion of the other areas if a new strategy is not yet in place

 v                          Infested properties will not be subject to surveillance by the ABGC. These growers are expected to undertake their own surveillance and must report suspect plants to BQ as a requirement of section 42 of the Act.

 vi                        An extra surveillance visit to banana properties impacted by a Tully River flood event will occur within the first 12 months, to commence at approximately 6-month intervals following their previous surveillance event.

This method of on-the-ground surveillance allows the ABGC to monitor large areas effectively, ensuring that potential outbreaks are identified and addressed before they can spread uncontrollably.

 Buffer Zones and Risk Management

To prioritise surveillance efforts, buffer zones are established around known infested areas. These zones, typically extending about 38km from the site of infection, serve as protective areas to monitor the risk of TR4 spreading. Factors such as water flow, movement of machinery and human activity are considered in determining the extent of these zones.

The ABGC has developed this surveillance strategy based on scientific principles, using data from past outbreaks and modelling techniques to assess the risk of disease spread. This approach allows the team to focus resources where they are most needed, ensuring that surveillance efforts are both efficient and effective.

Sampling and Diagnostics

Banana plants that are flagged as showing external symptoms of TR4 will be further examined by ABGC SO’s, in line with established standard operating procedures based on the approach used by BQ. If internal examination reveals symptoms consistent with the disease, then a sample will be taken and sent to the Department of Primary Industries (DPI) Plant Biosecurity Laboratory for diagnostic testing, in line with established protocols. Molecular diagnostic tests and vegetative compatibility group testing are used as part of a suite of diagnostic testing to confirm the presence or absence of the disease.

The Future of Surveillance: A Risk-Based Approach

As part of ongoing improvements, the ABGC is moving towards a more refined, risk-based approach to surveillance. This will consider not only proximity to known infected areas but also factors like soil and water movement, the presence of disease vectors, and other environmental conditions that increase the likelihood of Panama TR4 spreading. The risk-based approach aims to focus surveillance on the most vulnerable properties, enhancing the efficiency and accuracy of disease detection.

The new strategy will use science-driven methods and risk-based sampling to predict potential disease hotspots. This approach is expected to make surveillance more targeted, minimizing the impact on farms that are less likely to be infected.

Surveillance for TR4 is essential for the long-term sustainability of the banana industry. Through early detection and systematic monitoring, the ABGC’s strategy aims to protect both individual farms and the broader banana growing community. Surveillance will be conducted in the same manner that has been used previously, and draw on scientific methodologies, industry collaboration, and a focus on effective biosecurity practices.  

Ultimately, the science behind surveillance is about creating a balance – helping to protect farmers' livelihoods while ensuring that the banana industry remains healthy and viable for future generations.