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Abstract
The presence in New Zealand of the reversion disease of black currants was demonstrated by the development of typical symptoms in susceptible cultivars after graft inoculation. Reversion appears to be responsible for the serious crop losses occurring in Otago and Southland regions. It is not restricted to those areas, but occurs at a low incidence in Canterbury and Nelson regions. Spread has occurred through the use of infected cuttings during propagation, and probably also by the gall mite vector. Red currant vein banding disease was detected in several red currant cultivars by graft inoculation to red currant seedlings, and to the indicator B1385/81, but is of low incidence. The disease boysenberry decline, possibly caused by a mycoplasma-like organism, occurs in the northern half of the North Island. During the 1980s it appeared to be spreading rapidly until the removal of most infected plantings greatly reduced its incidence. The boysenberry leatbopper is a possible vector, but in controlled glasshouse and field trials natural spread of the disease by this agent has not been observed. A leaf variegation symptom, widespread in several black currant cultivars in New Zealand, may be a non-transmissible syndrome.