Tomato Ringspot

Tomato ringspot is a viral disease that can kill far more than your dreams of sweet summer salsa.

​This virus infects an astounding number of other plants and is fatal.

Tomatoes infected with tomato ringspot virus (sorhocam.com) Public Domain

In addition to tomatoes, the tomato ringspot virus infects stone fruits, apples, grapes, cucumbers, cowpeas, beans, strawberries, currants, soybeans, and cane fruit, including those luscious raspberries and blackberries. This disease also infects begonias, geraniums, iris, hydrangeas, and many other popular garden flowers. Dandelion seeds can also carry this disease. Sadly, tomato ringspot is an incurable, highly contagious disease. Infected plants, and their neighbors, should be removed completely to prevent further spread.

Tomato ringspot virus on currants (USDA) Public Domain

The virus responsible for tomato ringspot can be carried through the air, on pollen, or by dagger nematodes in the soil. As they feed on roots, they transfer the virus to healthy plants. 

Symptoms of tomato ringspot

Plants infected with tomato ringspot may fail to thrive but have no symptoms, acting as a way station for the disease without being impacted directly. They may slowly decline. You may see chlorosis or mottling. Cane fruits may turn dry and crumbly, similar to dryberry mite infestations. Stone fruits may develop prunus stem pitting or yellow bud mosaic.

    Yellow bud mosaic causes lower branches to lose leaves, moving upward into the canopy as the virus spreads. Leaf veins on either side of the midrib may turn white, and leaflike growths, called enations, may grow along the midrib on the underside of the leaf.

    Prunus stem pitting causes late leafing out. Leaves look pale and tend to wilt in summer, turning red or purple early in the season. Fruit size, quantity, and quality are all reduced due to the virus blocking the flow of water and nutrients through the graft union, effectively starving the tree. These symptoms can be mistaken for root damage caused by rats and voles, girdling roots, and fungal diseases. The difference is that the tomato ringspot disease causes the bark, above and below the soil line, to thicken and become spongy. This weakened area often allows the tree to topple over. Before that happens, you will also see pitting in the sapwood of the trunk. Usually, the tree dies before pitting occurs in any branches.

How to control tomato ringspot

In a word - you can’t. The disease is incurable and infected plants put nearby plants at risk. All you can do is remove the infected plants and those nearby and toss them in the trash. Just because symptoms disappear does not mean the infection is gone. Plants that no longer show symptoms can still spread disease throughout the garden. After removing infected plants, the affected area should be allowed to go fallow for at least eight months to starve out any dagger nematodes lurking underground and remove any potential disease-carrying weeds.

These tips can help prevent tomato ringspot:

• Quarantine new plants.
• Use certified pest- and disease-free plants.
• Plant disease-resistant rootstocks.
• Disinfect tools regularly.
• Remove infected plants and those surrounding them.

While removing plants from the garden or landscape is disappointing, removing more plants because of an initial delay is worse.