Blooming good news for floriculture

WESTERN Australia’s protea cut flower industry will soon be flourishing through the work of PhD student Chris Dunne.

Working with collaborators at Department of Agriculture and the Western Australian Protea Growers Association, Chris focused on Sudden Death, a phenomenon where up to 50 per cent of a farmer’s Protea crop can die almost overnight.

“We found that approximately 40 per cent of the properties that were surveyed had suffered from Sudden Death, and autopsies of the plants demonstrated that the major causal agent was Phytophthora cinnamomi, the Jarrah dieback fungus,” Chris said.

“Further tests suggested that other fungal pathogens and exposure to severe environmental conditions were also attributing to the Sudden Death syndrome.

“Phytophthora can affect up to 25 per cent of native vegetation in South West WA, but the main control strategy is to spray the plants with the fungicide, phosphite. Unfortunately, phosphite is not very effective in Proteas”.

With the main defence against Phytophthora not accessible for Protea farmers, Chris developed an innovative strategy to combat the pathogen with a chemical occurring naturally in Brassica plants (Indian mustards, fodder rapes).

“Canola and other Brassica plants have glucosinolate chemicals that convert into toxic compounds called isothiocyanates that act as a natural chemical defence,” Chris said.

“We developed a way to use these chemicals as biofumigants to protect Protea plants through mulching the Brassicas and incorporating it through the top soil. Biofumigation is a great alternative to the use of synthetic chemical fumigants that are frequently used in agriculture and horticulture, such as metham sodium and methyl bromide. Therefore, “integrating biofumigation with a series of other ‘green’ control measures such as solarisation, composting and the sterilisation of irrigation water will provide a first step for Protea farmers to reduce the impact of this devastating pathogen.

“Biofumigation also holds a lot of promise for other economically valuable horticultural crops such as strawberries, tomatoes, Boronia, Geraldton waxes, macadamias and avocadoes. In addition to Phytophthora diseases, biofumigation has also been shown by other researchers to control other plant pathogens.”

Farmers are encouraged to try the Biofumigation technique on Phytophthora infected sites. Chris plans to continue his work in disease management in WA ecosystems after finishing his PhD at the end of the year.

This research project was funded by the Australian Research Council Strategic Partnerships with Industry program.