Why Are My Fig Leaves Going Pale and Bronze?

If your fig tree's leaves are developing a stippled, pale or increasingly bronze appearance — as if the colour is being leached out of the upper surface — and on close inspection you can see fine silky webbing on the underside of the leaves along with tiny moving dots, your fig tree has red spider mite. This pest is one of the most common problems affecting container-grown fig trees, particularly those kept in warm indoor conditions or in glasshouses, but it also affects outdoor figs during hot, dry summers.

Identifying red spider mite

Two-spotted spider mite (Tetranychus urticae) is the most common species on fig trees. Despite the name, the mites are not always red — they are often yellowish-green with two dark spots on the body. They are tiny (under 1mm) and most easily visible on the underside of leaves where they feed. The first symptom is the fine pale stippling on the upper leaf surface caused by the mites puncturing individual leaf cells to feed on the contents. As the infestation progresses, the stippling merges into a general pale bronzing, and webbing becomes visible.

Why container and indoor figs are most affected

Red spider mite thrives in warm, dry conditions with low humidity — exactly the conditions found in a centrally heated conservatory, greenhouse or indoor room during summer. Outdoor figs in a normal UK summer are less severely affected because higher ambient humidity and natural predators (particularly the predatory mite Phytoseiulus persimilis) keep populations in check. Moving a container fig indoors or into a glass structure during hot weather without adequate ventilation creates ideal mite conditions.

Increasing humidity to slow mite spread

Misting the leaves with water, particularly on the underside, significantly slows mite reproduction by raising the local humidity around the plant. Misting twice a day in hot conditions is not excessive for a heavily infested plant. Stand container figs on trays filled with damp gravel or pebbles to maintain humidity around the foliage. Ensure good ventilation rather than sealing the plant in a hot enclosed space.

Biological control with predatory mites

Phytoseiulus persimilis is a predatory mite commercially available from biological control suppliers that feeds specifically on spider mites. It is very effective in enclosed or semi-enclosed environments such as a greenhouse. Introduce the predatory mites as soon as spider mite is detected — they work best when the pest population is not yet overwhelming. This is a highly effective and non-chemical approach.

Plant-based sprays

Neem oil or fatty acid-based insecticide sprays applied to the undersides of leaves are effective against spider mites. Multiple applications at five to seven day intervals are required to break the breeding cycle. Ensure thorough coverage of the leaf undersides where the mites concentrate. Do not apply in very high temperatures or full sun as this can cause scorch on the treated leaves.