Rust: how to spot and manage it

What it is: Rust is a fungal disease that shows up as orange-brown powdery pustules on leaves. There are many types and most stick to one group of plants, but they all behave similarly.

How to spot it

• Raised orange, rusty-brown or reddish pustules, mostly on the undersides of leaves.
• Matching yellow spots on the top of the leaf.
• Heavy infections yellow the leaves and drop them, weakening the plant.

Plants it affects

Growing any of these? See our guides to beans, onions, garlic, leeks, mint and spring onions.

Beans, garlic, onions, leeks, silverbeet and a number of herbs are the common ones in a veggie patch.

What causes it and how it spreads

Warm, humid weather and leaves that stay damp. Spores spread on the wind and in splashing water, and build up where plants are crowded.

How to prevent it

• Space plants and keep airflow good.
• Water the soil, not the leaves.
• Rotate crops so rust doesn't build up in one spot.
• Remove affected leaves early to slow the spread.

How to manage it

• Pick off and bin affected leaves (don't compost them).
• For a stubborn case, a copper or sulfur spray is the fallback.

For the bigger picture, see our guide to managing pests and problems safely.

Plan your patch: our free planting calendar shows what to plant now where you live. Ready to grow? Browse our raised garden beds or build your own with the garden bed builder.

Image: CSIRO, CC BY 3.0, via Wikimedia Commons.