Leaf spot

Worst in warm, wet, humid weather through summer and autumn, December to April.

Leaf spot covers a range of fungal and bacterial diseases that pepper leaves with brown or black spots, common on silverbeet, beet, tomatoes and many others. It rarely kills a plant but spreads on wet foliage and weakens the crop, so we remove affected leaves and keep foliage dry.

How to identify

• Small round brown, grey or black spots scattered over the leaves
• Spots with a darker ring or pale centre, sometimes with a yellow halo
• Spots joining into larger dead patches as it spreads
• Lower, older and shaded leaves affected first

How to prevent

• Space plants and prune for airflow so leaves dry quickly
• Water at the base in the morning and avoid wetting foliage
• Rotate crops and clear infected debris each season
• Use clean seed and resistant varieties where available

How to control organically

• Pick off and bin spotted leaves at the first sign
• Avoid handling plants while the foliage is wet
• Spray a copper-based fungicide as a protectant in wet weather
• Thin crowded plantings to open up airflow
• Clear all infected debris at the end of the crop