Olive pests and leaf spots: what to check

Separate olive scab from scale before acting: scab makes purple or brown spots with a halo, while scale may sit on leaves or twigs with sticky honeydew or sooty mold.

Plant coveredOlea europaeaOlive tree (indoor) · indoor and outdoor

Check the leaves, stems and pot

Look for pests or spreading spots

Inspect for olive-scab spots that are circular and purple or brown with a yellow or purple halo, and for scale coverings or sticky honeydew with sooty mold. These are distinct observations, not one explanation for every olive mark.

Check both leaf surfaces, young twigs, and fruit where present. Note whether spots have halos, whether scale is a fixed gray or black covering, whether honeydew or ants are present, how wet the foliage has been, and whether leaf fall is premature.

Use the visible signs to choose the next check

What the signs may mean

What could cause it

RHS links olive scab with olive-specific leaf spots and premature fall. UC IPM and UF describe armored scale or black scale as separate olive pests that can mark leaves, twigs, or fruit and produce honeydew or sooty mold.

What to do next

Start with inspection and hygiene: remove fallen diseased leaves and debris, prune clearly affected twig growth with clean tools where RHS supports it, improve airflow, and avoid prolonged wet foliage. Isolate visible scale while its identity is checked.

Watch for new damage or recovery

What to check again

After removing debris or isolating a plant with suspected scale, recheck new leaves, leaf undersides, and twigs for new spots, coverings, or sticky residue. The sources set no indoor recheck interval.

Do not diagnose from one sign alone

What visible signs cannot tell you

Sources