In a recent webinar hosted Dr Rob Beresford of PFR shared interim findings from his research into non-synthetic fungicide options for controlling myrtle rust.

Funded by MPI, the study involved glasshouse and field trials using a range of alternative products on the highly susceptible cultivar Lophomyrtus ‘Red Dragon’. Each treatment was assessed for both efficacy in preventing infection and any adverse effects on plant health (phytotoxicity).

While synthetic fungicides remain the most effective option, some promising results emerged from alternatives:

• Copper-based fungicides (oxide, oxychloride, hydroxide) and sulphur offered moderate protection with minimal phytotoxic effects.
• Sodium bicarbonate (5%) was somewhat effective in preventing infection but caused severe plant damage, including shoot dieback and suppressed growth.
• Lower concentrations of sodium bicarbonate and potassium-based products (bicarbonate and silicate) were less effective and still showed moderate to high phytotoxicity.

A full report is due next month, after which NZPPI will update the Myrtle Rust Prevention with Fungicides protocol to reflect the latest science.

Rob's webinar will soon be uploaded to the Beyond Myrtle Rust website.