Integrated disease management of citrus black spot and ‘Emperor’ brown spot (CT20009)

What was it all about?

This investment developed practical, field‑tested guidance to help mandarin growers manage citrus black spot (CBS) and ‘Emperor’ brown spot (EBS) under increasing residue, crop safety and market pressure.

The research develop management practices that can improve fruit quality through integrated disease management approach while meeting export requirements. Key findings included identifying promising low‑residue and alternative fungicides, clearer guidance on safer copper use, and strong evidence that canopy hygiene plays a major role in reducing disease.

The project tested new fungicide options and copper programs in commercial orchards across several seasons. Trials assessed low‑residue chemistries for late‑season use, SDHI‑based fungicides for early‑ to mid‑season control, spray timing and frequency, and how copper formulation, pH and timing affect fruit marking. The research also examined whether dead wood and pruning debris in the canopy act as disease sources.

The project addressed the challenge growers face in controlling CBS and EBS while managing phytotoxicity risk, fewer effective fungicides and tighter export residue limits. Traditional programs alone are becoming harder to sustain, particularly in subtropical conditions with high disease pressure.

Results showed that maintaining clean canopies and targeting sprays during key infection periods are critical. New fungicide options may expand future choices once registered, and improved copper practices can reduce fruit injury. Together, these outcomes will support more reliable, integrated disease management and better export fruit outcomes for growers.

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Access the Integrated Disease Management for Foliar and Fruit Diseases of Citrus guide here.

Download a fact sheet on Inoculum management in citrus nurseries.