Tomato black ring virus

(TBRV)

Tomato black ring virus (TBRV, Nepovirus) is found worldwide and occasionally infects the potato, causing heavy losses (yield reduction of 20 to 30%, and up to 80%). It has been identified in Germany, Eastern Europe and in the United Kingdom but has not been reported outside Europe.

The tubers present severe cracking and deformation making them unmarketable.

On the leaves, the primary infections may take the form of necrotic rings and spots  and the secondary infections the form of deformations (frayed leaves, leaf curl, etc.) accompanied by necrosis and sometimes severely reduced plant growth.

TBRV is transmitted by free-living, soil-inhabiting nematodes of the genus Longidorus. Nematodes acquire the virus from infected plants after feeding and retain the ability to transmit it for many weeks in the soil without finding host plants. The virus is also transmitted, often with a high frequency, through the seeds of infected plants, especially in some crop species and weeds. Many plants infected through the seed show no symptoms. Besides aiding dissemination of the virus, infection of the seeds seems to provide an important means of survival of the virus in soils.

TBRV infects a wide range of herbaceous and woody monocotyledonous and dicotyledonous species including many important crop plants such as Vitis vinifera, tree fruit and small fruit species, sugarbeet, potatoes and many vegetables (e.g. species of Allium, Beta, Brassica, Lactuca, Lycopersicon, Phaseolus) and ornamentals.

TBRV can usually be detected by the Elisa test.

TBRV is listed as a quarantine organism in North America (for NAPPO) but not by the EPPO because it is not regarded as a virus of great economic significance. It is already widely distributed thanks to its wide host range and that of its vectors and is more appropriately controlled by certification schemes.