Aculus fockeui Nalepa Trouessart Plum rust mite

Recently, infestations of this generally common pest have become more significant (at least in some areas). The mites inhabit the underside of expanded leaves of both fruiting and ornamental species of Primus, often in considerable numbers. Infestations on young leaf trusses result in the development of large spots on young green shoots, a distinctive yellow flecking of the leaves and, sometimes, distortion. Heavy populations may cause severe bronzing and lead to the death of young leaves. Along with certain other free-living species, the mites attack both established and young trees and are sometimes troublesome in gardens, nurseries and orchards. Some fruiting cultivars, especially Victoria, are particularly susceptible.

Cecidophyopsis ribis (Westwood) Black currant gall mite

This mite is an important and widely distributed pest of black currant. The mites induce the formation of characteristic 'big buds'. Also, leaves that emerge from infested apical shoots are often deformed and have rounded outlines to the main lobes. Affected bushes grow vigorously but crop poorly. 'Big buds', that may reach 15mm in diameter, are particularly noticeable after leaf-fall. They remain on bushes throughout the winter and into the following summer, when they eventually dry out and die. Although having a direct effect on host plants, black currant gall mite is of greatest significance as a vector of reversion virus disease. The presence of this virus is often a major cause of the decline of bushes and it will shorten considerably the economic life of plantations.


Black currant gall mites live and breed within the shelter of swollen, galled buds, each of which may contain many thousands of individuals. Adult mites begin to emerge from these 'big buds' in the early spring, from the grape growth stage onwards; emergence is favoured by warm, humid conditions, the mites often swarming on the outside of the galls in considerable numbers. Individuals eventually migrate over the bushes and are also carried from bush to bush by insects, wind or rain. This dispersal period lasts into the summer but is at its peak in May, from early flowering to early fruit swelling. New buds are invaded in June or early July, when egg laying begins. The mites breed rapidly within the buds from early summer onwards, particularly as the buds begin to swell, and populations reach their maximum in September. Egg laying ceases temporarily in the early winter but resumes in January; breeding activity reaches a second peak in the early spring, when attacks may also spread to the growing points of apical shoots.


Adult mite 0.2-0.4 mm long, whitish and vermiform; hysterosoma finely cross-striated, with equal numbers of tergites and sternites; prodorsal shield setae absent.

NOTE Similar-looking mites associated with other Ribes hosts are recognized as distinct species, e.g. Cecidophyopsis grossulariae Collinge on gooseberry and C. selachodon Eyndhoven on red currant.

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