Systemic Fungicide Rotation
Systemic triazoles and strobilurins for curative action against rust and powdery mildew.
Unlike contact fungicides, systemic products move inside plant tissue, giving them limited curative action against an outbreak that has already started — but that same mobility is what makes resistance management non-negotiable here.
Step-by-step protocol
- Scout weekly; treat at first pustule or 5% incidence.
- Apply propiconazole (250 g/L) at 0.5 mL/L, thorough coverage.
- Rotate to azoxystrobin (250 g/L) at 1 mL/L to preserve efficacy.
- Never make more than two consecutive applications of the same FRAC group.
Frequently asked questions
Can systemic fungicides cure an existing infection?
They offer some curative action within the first few days of infection, but they work best as part of a rotation started at first symptom rather than as a rescue treatment for advanced disease.
Why limit consecutive applications of the same FRAC group?
Using the same mode of action repeatedly accelerates fungicide resistance in the pathogen population, which is why rotating FRAC groups is standard resistance-management practice.
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