VIRTIGATION partners have contributed to the recent update of the EPPO Pest Risk Analysis (PRA) for the ToBRFV virus.
Article by Tiziana Centofanti from the VIRTIGATION project
ToBRFV - the unseen invader
Since 2020, ToBRFV has been slipping into the EPPO region through various pathways, including infected fruits and seeds. Despite efforts by EPPO countries and plant health stakeholders to block its entry, the virus has found numerous ways to spread, particularly through seeds of pepper and tomato, plants for planting, and even through the tools and vehicles used in farming. The updated PRA reports that while some EPPO countries have since then tightened their regulations, the virus remains a persistent threat to the region.
Once it has established a foothold, ToBRFV finds a welcoming environment, especially in greenhouses. Countries like Israel, Jordan, Greece, Italy, and the Netherlands have already reported established populations. The virus thrives under protected conditions, where it can easily spread and develop. Outdoors, its establishment is also likely, though it faces more challenges depending on local farming practices, according to the EPPO’s updated PRA.
A rapid spread impacting growers worldwide
The ToBRFV plant virus can spread with alarming efficiency. ToBRFV is a virus that is mechanically transmitted, meaning human activities play a significant role. Workers, visitors, tools, and equipment can all carry the virus from one plant to another, making containment a daunting task. The trade of plants, seeds, and fruits further accelerates its spread. In 2020, EPPO members reported outbreaks in 9 EPPO countries, whereas in 2024, this was already the case in 31 countries, as stated in the updated PRA for ToBRFV.
For tomato growers, ToBRFV is a formidable adversary. It overcomes the established TM-22 tobamovirus resistance genes in tomato crop, reducing plant vigour and causing yield losses. The fruits often become unmarketable due to the virus’s symptoms. In addition, research has shown that the virus was also able to break the resistance of a new resistant tomato cultivar. While the impact on pepper production is currently minimal, the economic and social toll on tomato growers is significant. The costs of surveillance, outbreak declaration, eradication, and hygiene measures add up quickly.
Value chain actors fighting back against ToBRFV
Despite the challenges, there is hope. Hygiene measures, resistant varieties, and seed testing are making progress in reducing the impact of ToBRFV. The EPPO’s Expert Working Group on ToBRFV still recommends classifying ToBRFV as an A2 quarantine pest, as some countries remain unaffected, as noted in the EPPO’s updated PRA.
One biological technique that can be used to fight ToBRFV is a cross protection strategy. This method works by stimulating the plant’s immune response: by pre-infecting the tomato crop with a mild strain of the ToBRFV virus, the plant becomes primed to defend itself against future infection with more aggressive strains. As a result, severity of symptoms and potential yield losses could be reduced, thereby protecting the overall health and productivity of tomato plants. The feasibility of this strategy to combat ToBRFV infection is not certain yet and is being thoroughly researched in the VIRTIGATION project. VIRTIGATION partners will thoroughly evaluate potential cross-protection candidates under different environmental conditions, in different cultivars and under different stressors to ensure that they are stable and mild under all conditions.
Risk Management Strategies for ToBRFV
To reduce the probability of entry, the EPPO considers various risk management options in its updated PRA for the virus. These include measures for host seeds, plants for planting, fresh fruits, used containers, tools, equipment, and conveyance vehicles. Hygiene practices have proven effective at the plant production level, including the treatment and disinfection of greenhouse surfaces, irrigation systems, seeds, soil, and the disposal of crop material.
New resistant varieties could also minimise the impacts of ToBRFV. The EPPO Panel on Phytosanitary Measures recently suggested that, based on the pest situation, EPPO countries might implement certain measures under different regulatory frameworks, such as RNQP (Regulated Non-Quarantine Pests) and ISPM (International Standards for Phytosanitary Measures) from the IPPC.
VIRTIGATION contributions to the EPPO PRA update
Several VIRTIGATION partners contributed to the recent EPPO update of the PRA for ToBRFV. This included Inge Hanssen (DCM CORP), Elise Vogel (DCM CORP and Scientia Terrae), Aviv Dombrovsky and Moshe Lapidot (Volcani Center), Heiko Ziebell (JKI) as well as Heike Scholz-Döbelin (LNW). Inge Hanssen, Aviv Dombrovsky and Heiko Ziebell are part of the EPPO’s Expert Working Group on ToBRFV, while the other members contributed outside of this framework to the PRA update. Furthermore, VIRTIGATION advisory board member Valérie Grimault, EPPO Assistant Director, also contributed to this crucial update.
The EPPO highlighted various research advancements of VIRTIGATION in the field of ToBRFV in the PRA update. It underlined the work of Christine Vos (Scientia Terrae) in observing that mixed infections of ToBRFV with aggressive PepMV isolates were much more devastating for the plant than a combination of ToBRFV with a mild PepMV isolate. The EPPO also welcomed the project’s research on methods concerning substrate disinfection such as solarization, for countries located in the south of the EPPO region, and steaming.
A glimmer of hope in the battle against ToBRV
As the battle against ToBRFV continues, the combined efforts of growers, researchers, and regulatory bodies offer a glimmer of hope. With vigilant management and innovative solutions, the spread of this tenacious virus can be curtailed, safeguarding the future of tomato cultivation in the EPPO region.
In line with these efforts, VIRTIGATION is leading the charge making strides in combating the devastating ToBRFV plant virus. With innovative solutions and a proactive approach, VIRTIGATION is seeking to help turn the tide against this relentless virus, ensuring that tomatoes can continue to thrive as a key crop for billions of people.
