Evaluation continues

Candidate

TSWV has an extremely wide host range with more than 1 300 plants including agricultural crops, wild and weed species (Parrella et al., 2003; Peters, 2003), but the Council Directive 2000/29 is restricting measures to only 10 host plants. TSWV is a systemic pathogen and, as such, it is very efficiently transmitted by all vegetative multiplication techniques (EFSA-PLH, 2012). The virus is transmitted by thrips in a persistent propagative mode (Ullman et al., 1993; Wijkamp et al., 1993). Because of the persistence of TSWV in the vectors, the virus can be carried by infected plant material but also by viruliferous thrips, which can be present on a consignment that is infected with TSVW or even on consignments of non-host plants of the virus. The interception reports in EUROPHYT (very few) indicate that TSWV is found mostly in consignments of ornamentals and in 2011 and 2012 it has been reported four times on Lycopersicon esculentum. TSWV and viruliferous thrips are being transported in living planting material and will survive transport and storage as long as their hosts remain alive (EFSA-PLH, 2012). The plants for planting are a significant pathway compared to other pathways.

Yes

TSWV infections in tomato occurring at an early stage in development result in severe stunting of plants, poor fruit setting and, when fruits eventually develop, fruits that are small and with yellow, brown or necrotic spots or rings (EFSA, PLH, 2012). TSWV causes yield and quality reductions and unappealing symptoms that render fruits unmarketable. While quantitative data on yield loss in crops and ornamentals are generally lacking, losses from TSWV diseases are considered very serious (Verhoeven and Roenhorst, 1994; Scholthof et al., 2011). TSWV is considered a very important pathogen of tomatoes, and severe losses have been encountered in crop production in Italy, Spain, Bulgaria and Greece. A great impact on tomato yield was reported by Moriones et al. (1998) in studies of natural TSWV infections in experimental plots in Northern Spain. Field experiments in Turkey, in which plots were naturally infected with TSWV, resulted in crop losses of up to 42 %, with an almost complete loss of marketable tomatoes (Sevik and Arli-Sokmen, 2012). Recently (2014 and 2015) TSWV infections affected tomato and pepper production (outdoor and indoor) in some Southern parts of Bulgaria.

Major

No

Candidate

The potential economic impact of TSWV is rated as major because the yield and/or quality losses are considerable; targeted controls are frequently needed and the treatment is costly.

candidate

The most efficient and technically feasible risk reduction options (EFSA-PLH, 2012) are those addressing either the sanitary status of the propagation material or those addressing the control of TSWV epidemic development through actions directed at the virus or at its vectors. Inspection and testing for presence of TSWV or of its thrips vectors can be effective to ensure virus freedom of plants. Testing is necessary to ensure that the virus in asymptomatic plants does not evade detection. Production of plants for planting in PFPSs is a highly feasible and effective risk mitigation measure when adequate detection surveys are in place. Control methods (chemical and biological) against thrips vectors can reduce the incidence of TSWV at the place of production. The most important step in insecticide management of thrips is to initiate insecticide applications when the densities are low. Growing TSWV host plants under exclusion conditions may be highly effective in the management of the virus and the thrips vectors in both field- and greenhouse-grown crops. Exclusion conditions for new plants moved in a production area are moderately feasible and effective as measures for prevention of the introduction of the infection to a healthy cultivation.