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Published: 3 May 2022

Close-up photo of leaves on a blueberry bush. The leaves show blueberry rust pustules on the underside of the leaves.

The Tasmanian Institute of Agriculture (TIA) will build on its current research into blueberry rust in Tasmania with new funding to develop on-farm management strategies.

The three-year study beginning in 2023 will test on-farm strategies for the prevention and control of blueberry rust in Tasmania.

The research will be supported by  almost $500,000 from the Tasmanian Government's  Agricultural Innovation Fund.

This builds on a current TIA study that is trialing alternative crop protectants for organic growers.

Along with Tasmanian blueberry growers, Fruit Growers Tasmania, Southern Cross University, and the Tasmanian Government will also be involved in the new research project.

Blueberry rust is caused by the fungus Thekopsora minima. Its presence can reduce yield and fruit quality. It reduces leaf area and function, causes premature defoliation and in severe cases, forms pustules on fruit.

When the new study begins in 2023, the research team, led by TIA Plant Pathologist Associate Professor Kara Barry, will focus on two key issues: managing rust on semi-evergreen and evergreen cultivars where infection persists on leaves over winter; and understanding what environmental conditions are optimal for blueberry rust survival and infection and relating these to both climatic conditions in Tasmania and the cultivars grown.

Additionally, the research will focus on defoliation studies, aimed at breaking the rust life cycle; rust survival and infection, which will assess the survival of blueberry rust spores (urediniospore) and mycelium (fungal filaments) under several environmental conditions; and rust survival models, which is intended to help growers identify when and where there is a risk of blueberry rust infection.

“Different methods of defoliation will be tested including organic and conventional products with the aim of achieving eight to 10 weeks of complete defoliation,” Associate Professor Kara Barry said.

“The best products will be tested in commercial orchard environments to measure the impact on bud development, fruit yield and quality over two seasons.

“Growers will be able to use the blueberry rust infection model with local weather data and weather forecasts to identify when there is a risk of blueberry rust infection.

“The rust survival model will help growers decide whether defoliation would be a useful strategy to prevent blueberry rust over-wintering in their orchard.”

Blueberry rust was first detected in Tasmania in 2014, but has been contained to 17 sites (April, 2022) including commercial and non-commercial blueberries.

Biosecurity Tasmania has managed the containment program and retained market access for commercial blueberry growers through site management protocols and property freedom surveys.

Quote from Peter Cross here

Assoc Prof Barry’s research team will also use DNA sequencing to compare blueberry rust in NSW and Tasmania, which will aid the team to confidently use the data from NSW blueberry rust survival studies to develop management strategies for Tasmania.

Additionally, the team will identify the timing and location of blueberry rust risk by collecting climate data from five Tasmanian blueberry farms. This will be matched to records of when blueberry leaf emergence and leaf fall occur.

“Identifying when and where there is a likely risk of rust infection will be modelled by combining climate and leaf data with detailed knowledge of the environmental conditions needed for rust survival and infection,” Assoc Prof Barry said.

“The models will also indicate the risk of where blueberry rust could survive winter conditions. This will help focus blueberry rust surveillance to high-risk locations.”

This article was published in Tasmanian Country Newspaper on 22 April  2022.