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APAL Spring Future Orchards webinar: Tackling Blackspot

Research & Extension

This webinar was presented as part of the APAL Spring Future Orchards® 2021 program.

The cool, wet spring this year is providing favourable conditions for apple and pear blackspot outbreaks, with frequent rain events making disease management more challenging.

Understanding the infection cycle of the blackspot fungus, the crop development stage and the weather conditions that favour infection and spread can help you to make decisions about the best time to apply control measures.

In this presentation, Horticultural Advisor Marcel Veens and apple orchardist David Finger discuss how they use disease forecasting and modelling based on weather and pathogen biology to make decisions to manage blackspot in apple and pear orchards.

Understanding how the disease works is important for managing it

Key points:

  • Blackspot is caused by Venturia inaequalis in apples and Venturia pirini in pears
  • Infection can occur as soon as green parts are visible on the tree infection (primary infection)
  • Leaves, buds, blossoms and fruit are affected
  • Getting in early to manage the disease can help to reduce build up of inoculum throughout the season, reducing the risk of more infections later (secondary infections)
  • The fungus can survive over winter, so poor disease control in one season can mean more disease in the next season

Where, when and what to apply?

Prediction models and weather forecasts can provide a warning that conditions are suitable for infection to take place and help with management decisions including when and what to apply. For example, if conditions do not favour infection, there is little point in spraying. Under some circumstances, it may be preferable to choose a protectant or curative, or product with a different mode of action.

Tools for decision making

Marcel says, “protection is always better than cure”. Knowing the conditions that are coming helps to make more informed decisions.

David: “There is no guarantee that you won’t get blackspot, but this is another tool for integrated pest and disease management.”

Further resources:

Read more about blackspot at ExtensionAus.

For more details on types of sprays and when to use them, refer to the DPI guide on Orchard Plant Protection

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