What's eating my wisteria floribunda?

Japanese wisteria shares the scale, aphid, and vine weevil susceptibility of Chinese wisteria. Scale insects on older stems are the most damaging long-term threat. Rabbits and deer may browse young plants, and leaf miners occasionally disfigure foliage. Because W. floribunda blooms on previous year's wood, protecting stems from scale dieback is essential for reliable flowering.

Brown waxy shells encrust stems; weakened wood produces less flower bud; honeydew leads to black sooty mould coating leaves and railings. Remove by hand-scrubbing with a stiff brush in winter; apply winter horticultural oil; treat crawlers in late spring with systemic insecticide if severe.

Irregular leaf margin notching by adults; root damage by white C-shaped larvae in the soil — particularly damaging on pot-grown plants. Apply nematode treatment (Steinernema kraussei) to soil in late summer; use vine weevil drench for pots; check compost of container specimens each autumn.

Colonies on young spring growth and flower stems cause sticky, distorted shoots and can reduce the number of blooms. Spray with insecticidal soap or neem oil; target growing tips early in spring before populations explode; natural predators usually assist from late spring.