Garden pest control - Big Bud Mite (Description and control instructions)

Scientific name: Cecidophyopsis ribis
Other name: Blackcurrant Gall Mite

The picture here shows the result of an infestation of tiny gall mites called Cecidophyopsis ribis, in the buds of a blackcurrant bush. As they feed the buds become enlarged and more rounded than pointed, fail to develop properly and eventually wither. As well as damaging the buds the mites can carry the currant reversion virus which alters the size and shape of the leaves, further reducing the vigour of the plant and fruit production suffers.
Gooseberry and Red Currant bushes should also be checked for their presence.

The mites breed in the buds during summer and autumn, overwintering there then increasing their numbers from January onwards ready to disperse as the buds open. They are only capable of crawling short distances so are carried to young healthy dormant buds by other insects, washed downwards the rain and on the wind. These dormant buds develop the following season.

Infestation usually occurs in the late spring or early summer so the bushes should be checked carefully and affected buds removed. If most of the branches are infected the entire bush should be destroyed. Growing nettles nearby is said to provide shelter for predatory insects and improve fruit yeilds.
Derris or pyrethrum can be used when the leaves are just emerging, after any enlarged buds are removed and burnt, but chemical control is not usually successful. If reversion disease has occured there is no remedy so the bushes should be burnt. Use only healthy plants from a certified source and plant in a new site if possible following an infestation.