The Tomato Brown Rugose Fruit Virus (ToBRFV) has emerged as a significant and relatively new threat to tomato and pepper crops across the globe. This plant pathogen is known for its rapid spread and the substantial concern it has generated within the agricultural industry.
What is Tomato Brown Rugose Fruit Virus
Tomato Brown Rugose Fruit Virus is a plant virus classified within the Tobamovirus genus. It was first identified in Israel in 2014, and subsequently, a separate outbreak was reported in Jordan in 2015. Since its initial discovery, ToBRFV has rapidly spread to numerous countries across Europe, Asia, Africa, and North America, becoming a global concern.
The virus is highly contagious and exhibits remarkable stability, allowing it to remain viable on various surfaces and in plant debris for extended periods. The presence of ToBRFV can lead to substantial economic losses for commercial growers, primarily due to significant reductions in marketable yield and compromised fruit quality.
Recognizing ToBRFV Symptoms
Identifying ToBRFV infection relies on recognizing specific visual symptoms that appear on affected plants. On leaves, common signs include a distinct mosaic pattern, characterized by areas of light and dark green, often accompanied by mottling or a marbled appearance. Leaves may also show yellowing between veins, blistering, or develop necrotic lesions, areas of dead tissue.
Symptoms on the stems can include brown necrotic streaks, particularly on the petioles (leaf stalks) and main stems. The most distinctive and damaging symptoms typically appear on the fruit. Infected fruits often develop rough, brown patches, sometimes described as rugosity (a wrinkled or ridged surface).
Fruit may also display green or yellow spots, particularly near the calyx (the leafy part at the stem end), and exhibit irregular ripening patterns. Additionally, fruits can become deformed or misshapen, further reducing their market value. The severity of these symptoms can vary depending on the plant variety, environmental conditions, and the stage of infection.
How ToBRFV Spreads
ToBRFV primarily spreads through mechanical transmission. This occurs when the virus is physically transferred from an infected plant to a healthy one via contaminated tools, equipment, or even the hands and clothing of workers. The virus particles can remain active on these surfaces for a considerable time, facilitating widespread contamination within a growing area.
Infected seeds are another significant pathway for the long-distance spread of ToBRFV. Similarly, the movement of infected plant material, such as seedlings or cuttings, is a common means by which the virus is introduced into new growing operations. Once present, the virus can spread rapidly through routine cultivation practices like pruning, tying, and harvesting, especially in high-density environments like greenhouses.
Preventing and Managing ToBRFV
Preventing the introduction and spread of ToBRFV requires strict adherence to biosecurity measures for growers. Sourcing certified disease-free seeds and seedlings from reputable suppliers is a foundational step to avoid introducing the virus from the outset. Once plants are acquired, new additions should be isolated from existing healthy plants for a period to observe for any developing symptoms before integration.
Rigorous hygiene protocols are essential for preventing mechanical transmission. This involves the regular disinfection of tools, equipment, benches, and surfaces that come into contact with plants, using appropriate viricides. Hands should be washed thoroughly and often, or disposable gloves should be used and changed frequently, especially when moving between different plant sections.
Wearing dedicated clothing and footwear within growing areas can help prevent the accidental transfer of virus particles from outside sources. Regular scouting for symptoms allows for early detection of potential infections. If ToBRFV is suspected or confirmed, prompt removal and destruction of infected plants are necessary to prevent further spread.
Infected plants should be carefully bagged and disposed of through burning or deep burial to ensure the virus is inactivated and prevent soil contamination. Isolating affected areas within a greenhouse or field and restricting movement can help contain outbreaks. Implementing crop rotation, where non-host plants are grown in previously affected areas, can also help reduce the viral load in the soil. Ongoing research focuses on developing tomato and pepper varieties with genetic resistance to ToBRFV, which offers a promising long-term solution for managing this persistent threat.
Is ToBRFV Harmful to Humans
Tomato Brown Rugose Fruit Virus is a plant-specific pathogen and poses no known health risk to humans or animals. It is not capable of infecting or replicating in human cells. While infected fruit may exhibit visual symptoms like rough patches or irregular ripening, making them unappealing for sale, they are entirely safe for consumption.