Scientific Name: Tomato apical stunt viroid

Describer: nan

Common Name: Tomato apical stunt viroid, TASVd

Title: Tomato apical stunt viroid found on Solanum jasminoides and Cestrum sp.

Summary:

Significance: During recent pospiviroid host surveys by Verhoeven et al. (2008, 2008b) samples from symptomless Solanum jasminoides and Cestrum sp. plants were found positive for Tomato apical stunt viroid (TASVd). These finds represent new host records for TASVd.

The two positive samples for S. jasminoides were collected in Germany and the Netherlands but the plants were imported from Israel, a country where TASVd had previously been reported (Verhoeven et al., 2008).

The positive finds on Cestrum sp. occurred with samples taken from nurseries in the Netherlands (Verhoeven et al., 2008b). Trace backs, trace forwards, and eradication efforts are underway.

Issues of Concern: Certain strains of Tomato apical stunt viroid are reported to be very damaging to tomato (Antignus et al., 2002). This concern has led EPPO to list the viroid on their "EPPO Alert List" (EPPO, 2007). The viroid is known to occur in Israel (in greenhouse tomato systems), Indonesia, Cote d'Ivoire, Senegal, and Tunisia (EPPO, 2008). 

Solanum jasminoides, also known as the potato vine, is a plant native to Brazil but is grown as an ornamental in warmer climates or greenhouses of North America (Monrovia, 2008). Verhoeven et al. (2008) report that TASVd did not reduce the quality of the S. jasminoides; the plants were symptomless. Since S. jasminoides is grown as an ornamental in parts of North America it could act as an infection source for other crops, such as tomato, where the damage can be significant. 

Cestrum species are also grown as ornamentals in warmer parts or greenhouses of North America (Monrovia, 2008) and like S. jasminoides the sampled plants displayed no symptoms (Verhoeven et al., 2008b). 

Antignus et al. (2007) reported that TASVd can be seed transmitted, but also spread by bumble bees (Bombus terrastris).  In a greenhouse tomato system, seed transmission could initiate a TASVd outbreak with secondary spread by bees brought in for pollination or mechanical spread by workers (Antignus et al. 2007).  Antignus et al. (2007) found no evidence of transmission by naturally or artificially infested growing medium or transmission by Myzus persicae or Bemisia tabaci (common greenhouse pests). 

To date, TASVd has not been reported from any NAPPO country. Control of viroids can be difficult in practice; therefore avoiding further spread of these types of organisms is a worthwhile objective.

References:

Antignus, Y., O. Lachman, and M. Pearlsman. 2007. Spread of Tomato apical stunt viroid (TASVd) in Greenhouse Tomato Crops Is Associated with Seed Transmission and Bumble Bee Activity. Plant Disease. 91(1): 47-50. 

Antignus, Y., O. Lachman, M. Pearlsman, R. Gofman, and M. Bar-Joseph. 2002. A New Disease of Greenhouse Tomatoes in Israel Caused by a Distinct Strain of Tomato apical stunt viroid (TASVd). Phytoparasitica. 30(5). 

EPPO. 2007. Tomato apical stunt pospiviroid: A new disease of tomato. European and Mediterranean Plant Protection Organization (EPPO). http. www.eppo.org. 

Monrovia. 2008. Monrovia Plant Library Online Search. https://azdomino.monrovia.com/MonroviaWeb.nsf/Splash!OpenPage  

Verhoeven, J. Th. J., C. C. C. Jansen, J. W. Roenhorst, S. Steyer, N. Schwind, and M. Wassenegger, 2008. First Report of Solanum jasminoides Infected by Citrus exocortis viroid in Germany and the Netherlands and Tomato apical stunt viroid in Belgium and Germany. Plant Disease Vol. 92(6):973. 

Verhoeven, J. Th. J., C.C.C., Jansen, J.W. Roenhorst. 2008b. First report of pospiviroids infecting ornamentals in the Netherlands: Citrus exocortis viroid in Verbenasp., Potato spindle tuber viroid in Brugmansia suaveolens and Solanum jasminoides, and Tomato apical stunt viroid in Cestrum sp. Plant Pathology. 57: 399.