Management of Apple Scab

Apple scab, caused by the fungus Venturia inaequalis, is one of the world’s most commercially significant apple diseases and a leading disease of concern for Australian apple growers. Major apple cultivars grown in Australia are highly susceptible to apple scab infection, which reduces the quality and size of fruit and can cause total crop failure without correct management.

The primary tool for managing apple scab is the application of fungicides. The number of applications required for adequate control varies depending on weather, but typically represents a significant input cost for growers. Lack of disease management tools and information can lead to more frequent use of fungicides, which also increases the risk of fungicide resistance developing.

V. inaequalis is considered a high-risk pathogen for the development of antimicrobial resistance. Large-scale testing in growing regions is required to understand the extent of fungicide resistance of V. inaequalis in Australia and mitigate the associated risks.

This project is designed to help Australian apple producers maintain best practice by minimising the use of pesticides for managing apple scab in their orchards. Using state-of-the-art molecular techniques and traditional testing methods, the project will identify the presence of fungicide resistance in V. inaequalis across major apple-growing regions in Australia, and investigate the pathogen’s population structure.

Cultivars within the Australian National Apple Breeding Program will also be screened for resistance to the disease. This will allow for future crosses that have both high-quality eating characteristics and apple-scab resistance. The creation of such crosses would support the long-term goal of breeding high-quality apple cultivars that do not require fungicide treatment to control V. inaequalis.

• Measuring the extent of resistance to different fungicides within the Australian population of V. inaequalis across major apple-growing regions
• Analysing the population structure of V. inaequalis in Australia to determine its genetic variability across different growing regions
• Cataloguing fungicide-resistance genes in V. inaequalis within the germplasm collection of the Australian National Apple Breeding Program and in field populations of V. inaequalis
• Understanding risk factors for fungicide resistance and informing best-practice management guidelines for farmers across Australia.

Australian apple growers, consumers

4.5 years

The Western Australian Department of Primary Industries and Regional Development (DPIRD) is responsible for regulating and advancing agricultural and food industries, fisheries and regional development within Western Australia.

Curtin University