Advice

RHS Help & Advice

Blackcurrant big bud mite (Cecidophyopsis ribis)

Symptoms

Damage is most easily seen in late winter, when infested buds have become abnormally swollen and rounded (left). Healthy buds are pointed and longer than broad (right). Infested buds often dry up, producing no leaves in spring, or stunted foliage and few or no flowers.

Biology

The mites are tiny, much less than 1mm in length. An infested bud can contain hundreds of mites, which feed by sucking sap from the embryonic leaves. They emerge in early summer, spreading over the plant in search of new buds to infest, when they can be blown by the wind onto other blackcurrant plants. The mite can also transmit a mycoplasma disease known as reversion. This debilitates plants, resulting in reduced yields of fruit.

Control

No pesticides are available to home gardeners for the control of big bud mite. Dispose of heavily infested plants after the fruit has been picked and replant in the autumn. One mite-resistant cultivar, ‘Ben Hope’, is available. The affected buds of lightly infested plants can be picked off and disposed of in winter.

Andrew Halstead