TOMATO BROWN RUGOSE FRUIT VIRUS – AN EMERGING THREAT TO UK TOMATOES AND PEPPERS What do we know about Tomato brown rugose fruit virus? Adrian Fox and Anna Skelton, from Fera Science, explore how the virus spreads and how it can be controlled.
In June 2019, Tomato brown rugose fruit virus (ToBRFV) was reported for the first time in the UK. The outbreak was promptly reported to the Plant Health and Seeds Inspectorate (PHSI) and necessary steps were taken towards virus eradication, including crop destruction. At the time of printing, no further outbreaks had been reported. Now that the disease has entered the UK, propagators and growers are advised to review their production protocols, particularly regarding imports of seed and plants, and crop hygiene. Tomato and pepper are the major economic hosts of ToBRFV, but inoculation trials have demonstrated experimentally that Nicotiana species, as well as Solanum nigrum, Chenopodium quinoa, Petunia hybrida and Chenopodium murale can act as minor hosts, showing slight symptoms.
18 AHDB Grower PROTECT
It is advised that glasshouse workers wear gloves when handling plants and these should be changed often. The virus is also likely to survive on clothing and hair SYMPTOMS
Symptoms of ToBRFV infection can vary with variety. In tomato, symptoms can include mild to severe mosaicism, discolouration of the leaves, with some leaves becoming narrower. Tomato fruits can be discoloured and misshapen, turning yellow or brown, with crinkling of the skin (rugose patches). Fruit can develop pale marbling similar in appearance to infection with other viruses such as Pepino mosaic virus. ROUTES OF INFECTION
ToBRFV is closely related to the Tobamoviruses Tomato mosaic virus and Tobacco mosaic virus. However, ToBRFV
can overcome the resistance genes to these viruses and, at present, there is no reported tomato resistance to ToBRFV. Tobamoviruses are stable outside of their host. The main routes of ToBRFV transmission are through propagation material (cuttings and grafts); contact through contaminated tools, hands and clothing; or plant-to-plant contact. As with other Tobamoviruses, it is also thought that ToBRFV is seed-transmitted. However, ToBRFV has not been found present within the seed, but rather on the seed coat, so good seed treatment protocols should reduce the risk of spread. It has also recently been reported that the virus can be transmitted by bumblebees during pollination.
