538 DISEASES OF CULTIVATED PLANTS 



caused by Eriophyes ribis (Nalepa), sometimes known as ' big 

 bud,' is unfortunately too well known to require a detailed 

 description. Diseased buds are known by their large size, 

 globular form, and in remaining on the tree for a considerable 



FiG. 163. Eriophyes ribis, causing ' big bud ' of black currant. 



time in an unexpanded condition in fact they are killed by 

 the mites, which are often present in thousands. During 

 early summer most of the mites leave the old dead buds and 

 migrate to the newly formed buds, where they remain for 



