Tomato and tobacco ringspot

About

Tomato ringspot and tobacco ringspot are two related viruses that infect many fruit, vegetables, flowers and weeds. Tiny dagger nematodes in the soil carry them from root to root, so they build up in one spot and slowly weaken perennial crops such as raspberries, blueberries and grapes. Infected plants can't be cured, and the nematodes stay in the soil.

Also called tomato ringspot virus, tobacco ringspot virus, ToRSV, TRSV, tomato ringspot, tobacco ringspot, ringspot virus, nepovirus, yellow vein disease, tomato ringspot decline, tobacco ringspot decline, bud blight

How to recognize it

Symptoms

Leaves show yellow rings, lines, flecks or mottling and may be small, cupped or misshapen. Red raspberries make small, crumbly berries and lose vigor. Blueberries get small cupped leaves, tiny brown spots on leaves and stems, and stunting. Grapes show yellow flecks and line patterns, short shoots and small clusters. Watermelon and other vine crops get mosaic, mottling or tiny brown spots with yellow halos on young leaves. Infected woody plants are more easily hurt by winter cold, and some decline slowly with few other signs.

Often confused with

Many other viruses cause rings and mottling, and slow decline can look like root rot. Only a lab test can name the virus, and a soil test can check for dagger nematodes.

Worse when

Soil with dagger nematodes, weeds that carry the virus (such as dandelion, chickweed and plantain), and replanting the same crop where sick plants grew.

How it spreads

Dagger nematodes pick up the virus while feeding on the roots of infected plants or weeds and pass it to the next roots they feed on, so it creeps slowly along a row (about 6 feet a year in raspberries). It also travels in infected nursery plants, and tobacco ringspot can move in seed and pollen. Nematodes reach new beds in soil carried on tools, boots and equipment.

When

The virus and nematodes persist in the soil year-round. Symptoms are often strongest on young plants early in the season, and damage to perennial plants builds over several years.

What to do, gentlest first

Prevention works best; most sprays only protect healthy leaves and can't cure infected ones. Always read and follow the product label.

1. Buy certified virus-free plants Prevent

   Buy certified, virus-free raspberries, blueberries, grapes and other fruit from a reputable nursery. Don't move suckers or daughter plants out of a patch that has the virus.

2. Clear weeds and old brambles Prevent

   Before planting, remove old raspberry plants, wild brambles and weeds such as dandelion and chickweed. Keep weeds controlled in and around the planting afterward.

3. Test soil and don't replant Prevent

   Have the soil tested for dagger nematodes before planting fruit. Where the virus has been found, don't replant the same crop; plant in a new spot, or switch to a plant that doesn't get it, such as black raspberries instead of red. Commercial growers often leave a site fallow or in a non-host grass for 18 months first.

   The nematodes stay in the soil, so new susceptible plants in the same spot will likely become infected.

4. Keep soil and tools clean Prevent

   Knock soil off tools and boots before moving to another bed, and work in healthy beds before infected ones. Oklahoma State also advises dipping pruners between cuts in 1 part household bleach to 9 parts water.

   Bleach corrodes metal, so rinse and dry tools afterward.

5. Remove infected plants By hand

   Once a lab confirms the virus, dig out infected plants, roots and all. They will never recover, and no spray cures them.

Plants it affects

Apple (backyard tree), Blackberry, Blueberry, Cantaloupe (muskmelon), Cucumber, Edamame, Geranium (annual, Pelargonium), Grape, Green beans (snap beans), Lettuce, Peach, Potato, Raspberry, Southern peas, Spiderwort, Strawberry, Tomato, Watermelon, Winter squash and pumpkin