Source: USDA Agricultural Research Service. Research announced in 2025; explained here for home gardeners.
A tomato virus that has worried commercial growers worldwide may have met a promising opponent. Researchers with the USDA’s Agricultural Research Service (ARS) found that an experimental tomato line developed in the 1990s shows good resistance to tomato brown rugose fruit virus, often shortened to ToBRFV. The virus can damage tomatoes and peppers, and it spreads easily, so it is worth every tomato grower knowing what it is and how to keep it out of the garden.
What the researchers found
ToBRFV belongs to a group called tobamoviruses, which also includes tobacco mosaic virus. It has been able to overcome the resistance genes bred into many current commercial tomato varieties, which is why it has caused so much concern.
The ARS team tested a tomato line known as tomatoNN, created decades ago by ARS scientists who moved a resistance gene (the N gene) from a wild tobacco relative into tomato to protect it against tobacco mosaic virus. According to the USDA, this line also resists ToBRFV at moderate temperatures of around 72°F (22°C), but the protection weakens at higher temperatures of around 86°F (30°C). The researchers say more study is needed on how temperature affects this resistance, and they see the line as a valuable starting point for breeding new resistant varieties.
Importantly for home gardeners, this is breeding research, not a new variety you can buy. It may lead to resistant tomatoes in the future, but for now, prevention is your best protection.
What this means for your garden
Know the warning signs
- Leaves with a mottled or mosaic pattern of light and dark green, sometimes distorted or narrowed.
- Fruit with yellow or brown patches, uneven ripening, or wrinkled, rough (rugose) areas on the skin.
- Reduced yield from affected plants.
Other problems can cause similar symptoms, so compare carefully with our guide to common tomato problems, try the plant problem identifier, and contact your local Cooperative Extension office if you suspect a virus. Many offices can help confirm a diagnosis.
Prevention is everything
The USDA notes that the virus is carried in seed and spreads easily through contact with contaminated tools, hands, clothing and infected plant material, and that cleaning and sanitizing are the most effective ways to manage it. In a home garden, that means:
- Buy seed and transplants from reputable sources. Seed-borne viruses often arrive with the plant.
- Do not save seed from plants that showed unusual mottling or fruit symptoms.
- Wash your hands before working with tomatoes and peppers, and between plants if any look unhealthy.
- Clean and disinfect pruners, stakes and cages regularly, and always after handling a suspect plant.
- Remove and bag suspect plants, including roots and fallen fruit, rather than composting them.
- Handle healthy plants first, and suspect plants last.
These habits also protect against other common tomato diseases, so they are worth adopting whether or not the virus is in your area.
The bigger picture
Tomatoes are the most popular crop in home gardens, and viruses that slip past existing resistance are a reminder of why plant breeding research matters. For now, healthy soil, clean tools, good spacing and reliable seed sources remain the foundation of a healthy tomato patch. Our guides to starting seeds indoors and starting a vegetable garden cover the basics of growing strong plants from the start.
Read the full release from the USDA Agricultural Research Service.