Hopes disinfectant against the rough
Tomato brown rugose fruit virus (ToBRFV, colloquially known as “rugose virus”) was first reported in Israel in 2014. It mainly poses a threat to greenhouse tomatoes, but also peppers, in Canada. And in the world. Infection of plants with the virus can cause symptoms, rendering the fruit unmarketable or prohibited for export. According to reports, crop losses ranged from 30 to 100 percent.
Like other Tobamovirus species, ToBRFV is known to be seed-borne and difficult to manage. It is easily transmitted mechanically by anything that comes in contact with the plant (eg workers’ hands, tools, etc.), and it is persistent in the environment. Biosecurity remains the main line of defense. Despite recent announcements from various seed companies regarding the development of tolerant and resistant varieties, resistant tomato varieties suitable for the greenhouse market are not yet widely available.
Recent studies show the effectiveness of disinfectants in eradicating the virus and should be of interest to producers.
For hand washing, a study from the UK has shown that the virus can survive on the surface of gloved hands for up to 120 minutes (maximum time tested). Only one product tested, Nzym Rugo, was found to be effective for washing hands after one minute of contact time. However, this product is currently not available in Canada. For this reason, it is currently suggested that workers wear gloves and change them frequently.
For surface disinfection, studies by the same group of British researchers have shown that the virus can survive for weeks or even months on greenhouse surfaces (glass, concrete, aluminum, hard plastic, polyethylene and stainless steel). Four of the six disinfectant products tested – Huwa San, Menno Florades, Javel and Virkon – were partially to fully effective on most surfaces after 60 minutes of contact time. But this time may be difficult to achieve or impossible for some applications (eg footbaths).
A recently published study by researchers at the United States Department of Agriculture examined the effectiveness of additional disinfectant products. Three products – bleach, Virocid and lactoferrin – has been shown to be very effective in inactivating the virus in test tubes, with a short contact time of up to 60 seconds. Five additional products – Virkon, trisodium phosphate, Lysol, Virex and SP 2700 – also showed some efficacy even with this short contact time.
Two recent studies also evaluated various seed disinfection protocols.
In the first study by Italian researchers, three heat treatments and three chemical treatments inactivated the virus at least partially, without significantly affecting seed germination. These chemical treatments with trisodium phosphate or sodium hypochlorite (the active ingredient in bleach) have been shown to be particularly effective.
In the second study conducted by collaborating researchers from Italy and Jordan, treatment with hydrochloric acid or sodium triphosphate resulted in complete inactivation of the virus, without negative impact on seedlings.
Disinfection is a key part of managing ToBRFV in the greenhouse. As research into the virus continues around the world, the list of potential disinfecting agents will continue to grow.
It is important for growers to confirm whether particular products and protocols are approved for greenhouse use. Not all of the products mentioned here are available or registered as greenhouse disinfectants in Canada. Different formulations and concentrations could affect the result and even pose a risk to the culture.
Producers interested in the products and protocols mentioned here are encouraged to discuss them with local extension specialists and seed suppliers.
Samarah, N. et al. (2020) Disinfection Treatments Removed Rough Tomato Brown Fruit Virus in Tomato Seeds. Eur J Plant Pathol https://doi.org/10.1007/s10658-020-02151-1
Davino, S. et al. (2020) Rough Fruit Virus of Brown Tomato: Seed Transmission Rate and Efficacy of Different Seed Disinfection Treatments. Plants 9, 1615; doi: 10.3390 / plants9111615
Geneviève Marchand, Ph.D., is a research scientist and plant pathologist at Agriculture and Agri-Food Canada, based at the Research and Development Center in Harrow, Ontario. Dante Cacciotti and Destin Lamondin are students of Niagara College.
This is one of a series of searches updates, written in collaboration with the students of the Hort1346 Greenhouse Production Course at Niagara College and initiated by instructor Sébastien Jacob.