Pests & Diseases

Diagnose problems and keep your silverbeet healthy.

Symptom Finder

Symptom	Likely cause	Action
Small round holes scattered across leaves	Flea beetles	Cover with insect mesh; neem oil spray
Sticky residue on leaves; ants trailing up the stem	Aphids	Blast with water; insecticidal soap
Pale winding tunnels inside the leaf	Leaf miners	Remove and bin affected leaves
Yellow patches above; grey-purple fuzz underneath	Downy mildew	Improve airflow; remove affected leaves
Small tan spots with dark purple border	Cercospora leaf spot	Remove leaves; copper fungicide
Seedlings collapse at soil level	Damping off	Improve drainage; use fresh seed compost

Common Pests

Pest

Aphids

Bladlus

Dense clusters of small green or black insects on stems and leaf undersides. Look for sticky honeydew coating the leaf surface and ants trailing up the stem (ants farm aphids for their honeydew).

Pest

Flea Beetles

Jordlopper

Tiny, scattered round holes in leaves, as if peppered with a pin. Most damaging on seedlings and young plants. The beetles themselves are 2–3 mm, shiny black, and jump when disturbed.

Pest

Leaf Miners

Bladminérflue

Pale, irregular tunnels or blotch-mines visible through the leaf surface: the larva of the fly Pegomya betae is feeding inside the leaf tissue itself. Affected areas turn brown and papery.

Common Diseases

Disease

Downy Mildew

Peronospora farinosa f.sp. betae

Pale yellow or brown patches on the upper leaf surface, with a corresponding grey-purple downy growth on the underside. Favoured by cool, humid weather and poor air circulation.

Disease

Cercospora Leaf Spot

Cercospora beticola

Small circular spots with a grey-tan centre and a distinct dark purple or reddish border. In warm, humid conditions the spots merge into large dead patches and leaves may drop prematurely.

Disease

Damping Off

Pythium / Rhizoctonia spp.

Seedlings suddenly collapse at soil level. The stem appears pinched, water-soaked, or shrivelled just above the soil line. Affected seedlings cannot be revived.