Leaf spot (septoria): how to spot and manage it

What it is: Leaf spot is a fungal disease that peppers leaves with lots of small, round spots. Septoria leaf spot is the common one on tomatoes — it won't touch the fruit, but it can strip a plant of leaves.

How to spot it

• Many small (2–3 mm) circular spots with a grey or tan centre and a dark edge.
• Sometimes tiny black specks in the centre of each spot.
• Starts on the lowest leaves and works up; leaves yellow and drop.

Plants it affects

Growing any of these? See our guides to tomatoes, silverbeet, celery, carrots and parsley.

Tomatoes most of all, plus silverbeet and chard, celery and parsley.

What causes it and how it spreads

Warm, wet conditions. The fungus lives in old debris and splashes up onto low leaves in rain or overhead watering.

How to prevent it

• Mulch to stop soil splash, and water the soil in the morning.
• Stake and space plants for airflow.
• Remove debris and rotate crops each season.

How to manage it

• Pick off affected leaves early and bin them (don't compost).
• If it spreads, a copper fungicide 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: Dr Parthasarathy Seethapathy, Tamil Nadu Agricultural University, Bugwood.org, CC BY 3.0, via Wikimedia Commons.