Blueberry Rust in Western Australia

The fungus Thekopsora minima causes blueberry rust. It is a serious disease that can cause extensive defoliation and occasional plant death. It is present in most Australian states where industry manage or prevent infection by good farm biosecurity and applying crop management practices that suppress fungal growth.

In April 2022 it was found in multiple locations in WA including the Perth metropolitan area, Manjimup, and Swan View. Suspect detections in Bunbury, Busselton, and Kalgoorlie have also been reported to the Department of Primary Industries and Regional Development (DPIRD). It is a declared pest under the Biosecurity and Agriculture Management Act 2007. This means you may not move, sell, or supply plants infected with blueberry rust to others.

Due to its spread in WA and the factors outlined below, the Department considers it is not technically feasible for the blueberry industry and government to eradicate blueberry rust from WA.

• High dispersal potential, including spores carried on the wind for long distances.
• Pest biology favours spread and establishment, making it very difficult to contain.
• The southwest WA climate is well suited for establishment and spread.
• Blueberry production in WA is mostly evergreen varieties, providing a green-bridge for rust development.
• Spread into urban areas would be difficult to detect, eradicate or contain.
• No reports of successful eradication or containment in Australia or overseas.
• Chemical controls suppress blueberry rust but do not eradicate it.
   

Blueberry rust is spread via spores carried by wind from infected plants, directly by people wearing contaminated clothing, on equipment that has been in contact with infected blueberries or by introducing infected plants. Young leaves are most vulnerable to rust infection. Rain events can trigger the release of spores and favour infection by increasing the humidity. Leaf wetness, due to rain and dew, provide conditions which assist in the severity of the disease.  Mild temperatures favour spore production and infection with temperatures between 19–25°C highly favourable. The latent period from infection to the observation of symptoms can be 10 days at 20°C for susceptible varieties. Infection leads to premature leaf drop and these leaves play a role in the ongoing disease cycle.

Fungicides control blueberry rust but do not eradicate it. Management is best if fungicides are applied in a preventative manner, prior to conditions that favour infection. The best time to apply preventative fungicides will vary according to variety grown and weather conditions.

Unsure if you have blueberry rust? Use the MyPestGuide® Reporter app to send a photograph to DPIRD. A specialist will examine your photograph and send you a diagnosis.

Refer to https://www.agric.wa.gov.au/pests-weeds-diseases/mypestguide for details on using the MyPestGuide Reporter app.

In accordance with national and international biosecurity agreements, the Department intends to update the status of blueberry rust in WA to ‘present’ and revoke its declared pest status.

What this means for industry

Where a pest is present and not under eradication or official control, there is no justification for WA import restrictions.

As host plant material and agricultural machinery used in association with hosts are restricted entry into WA based on the absence of blueberry rust, the Department will also revoke specific import restrictions for these items.

As WA is not free of blueberry rust, host material sent to sensitive markets will need to meet the import requirements as set by the importing authority.

For further information regarding movement and treatment requirements, please see https://www.agric.wa.gov.au/exporting-animals/quarantine-export-restrictions

The Department will support industry to adopt effective management practices for blueberry rust. This support includes advice on good farm biosecurity and crop management practices that help prevent or reduce blueberry rust infection.

These include:

• Restrict access to your property. Ensure visitors and equipment come in and go out clean.
• Prune to create an open canopy. This helps leaves dry faster and reduces humidity and the number of possible rust infections.
• Monitor your plants regularly: the earlier you can remove infected material, the more likely you will be to keep the rust at a manageable level.
• Implement a good farm/nursery biosecurity plan.
• Avoid overhead watering.