Tomato black ring virus

Tomato black ring virus is a nepovirus with a host range beyond that of its namesake, tomato. Other hosts include: grapes, potato, Allium species, beets, brassicas, lettuces and legumes. In practice, however, the most important hosts have proven to be cane fruit, Ribes species and strawberry.

Symptoms
Most naturally infected weed and crop plants may show few or no symptoms especially in the year of infection or when infection occurs through the seed. Nevertheless, plant growth and vigour in such plants may be impaired. Where infection occurs through nematode transmission, this often appears as patches of poor growth which slowly extend in size each year. Symptoms are generally most obvious in plants in early spring growth and are less noticeable during more rapid growth in summer.

Cane fruit & Strawberry
Depending on the cultivar, natural infection in cane fruit and strawberries may induce chlorotic mottling and/or ringspots in leaves.

Potato
Leaves may develop black necrotic spots.

Celery
Leaves may show bright-yellow vein-clearing.

Control
Avoidance of infection is by planting healthy material (seed or vegetative material) at sites free from infestation with Longidorus vector nematodes carrying the virus.

Chemical
At sites contaminated with infective nematodes, soil treatment with nematicides prior to planting can be used as a control. . This treatment kills most nematodes and also any infected weed and crop seeds that might act as virus reservoirs for the few nematodes surviving the soil treatment. To minimize the risk of reinfecting such treated sites through the presence of virus-infected weed seedlings, continued weed control is an additional and recommended treatment.

Cultural
The virus was eradicated from infected potato tubers and some fruit tree budwood by thermotherapy.