Bacterial spot

Updated June 2026

Worst in warm, wet, humid weather through summer, December to March.

Bacterial spot is a bacterial disease that peppers tomatoes, capsicums and chillies with small dark greasy spots on leaves and fruit. It spreads in warm wet weather and on splashing water, seed and hands, and there is no cure, so clean seed and dry foliage are the defence.

How to identify

• Small dark brown to black spots, sometimes with a yellow halo, on leaves
• Greasy or water-soaked looking spots that may have a pale centre
• Raised scabby spots on fruit
• Leaves yellowing and dropping when spotting is heavy

How to prevent

• Use clean, disease-free seed and seedlings
• Water at the base and avoid wetting and splashing foliage
• Space and stake plants for airflow
• Rotate crops and do not handle plants while they are wet

How to control organically

• Remove and bin affected leaves and fruit promptly
• Avoid working among plants while the foliage is wet
• Spray a copper-based product as a protectant in wet spells
• Pull out badly infected plants to limit spread
• Clear all crop debris and rotate away from hosts next season