Tomato black ring virus (TBRV) in Malling Exploit raspberry causes relatively mild symptoms, and for the first few years in the life of a plantation it may have no detectable effect on growth or fruit yield. Later, infected plants produce somewhat shorter canes than healthy ones and yield less. Fruits from TBRV-infected plants are malformed, with many undeveloped drupelets, and weigh less than healthy ones.
The nematode vector of TBRV, Longidorus elongatus, does not thrive on raspberry, and hence populations decline when this crop is planted. However, certain weeds and cover crops (e.g. grass/clover) are hosts for L. elongatus and maintain populations, as well as being reservoirs of virus infection.