Potato Target Spot, also known as Early Blight, is caused by the fungal pathogen Alternaria solani. To reduce the risk of fungicide resistance and preserve long-term efficacy of critical crop protection tools, CropLife Australia has released its updated 2025 resistance management strategy. These guidelines are endorsed by leading industry players such as Syngenta, with a shared goal of protecting yield, profitability, and sustainability across Australia’s potato sector.

Key Objectives of the Strategy:

• Reduce over-reliance on any single fungicide mode of action (MoA).
• Encourage rotation and alternation of fungicides from different groups.
• Support growers in applying fungicides preventatively and responsibly.
• Delay the onset of resistance through integrated disease management.

Fungicide Use Guidelines by Group:

• Group 2 (Dicarboximides): Maximum of 6 applications per season. No more than 2 consecutive uses.
• Group 3 (DMIs or triazoles): Maximum of 6 applications. Do not exceed 2 back-to-back sprays.
• Group 7 (SDHIs): Do not follow a Group 7 seed or in-furrow treatment with a Group 7 foliar spray. Limit to 2 consecutive foliar applications.
• Group 9 (Anilinopyrimidines): No more than 2 consecutive uses per season.
• Group 11 (QoIs or strobilurins): If applied in-furrow, the first foliar spray must be from a different group. Do not use more than 2 consecutive sprays. Follow with an equal number of sprays from other groups.
• Multi-site fungicides (Group M) and biologicals (Group BM): Considered low-risk and can be used more flexibly but should still be rotated with other MoAs where possible.

Syngenta’s Technical Recommendations:

Syngenta has expressed strong support for these updated strategies. Matt Sherriff, Technical Services Lead at Syngenta Australia, emphasized the importance of “using fungicides before disease pressure escalates” and ensuring strategic alternation of chemistry. Syngenta recommends the use of the following products in line with the strategy:

• MIRAVIS^® Duo: Contains Groups 3 + 7 fungicides. Registered for target spot and powdery mildew. Suitable for foliar spray and chemigation applications.
• MIRAVIS^® Prime: Contains Groups 7 + 12. Provides control of sclerotinia, botrytis, and target spot. Use preventatively before canopy closure.

Why This Strategy Matters:

With increasing global cases of fungicide resistance, especially within SDHI and QoI groups, proactive stewardship is essential. By adopting these updated practices, growers can extend the usable life of fungicide products, maintain yield integrity, and support the sustainability of the entire supply chain.

Growers are advised to implement these guidelines alongside non-chemical control measures such as crop rotation, resistant cultivars, and improved field hygiene. Consultation with agronomists and strict adherence to label directions remain essential.