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Tomato/tobacco
ringspot virus decline - Tomato ringspot virus, tobacco ringspot virus
Annemiek
Schilder, MSU Plant Pathology |
| Home > Scouting guide> tomato/tobacce ringspot virus decline |
These viruses occur
sporadically in vinifera grapes and interspecific hybrids. Labrusca grapes
are resistant. In the first year of infection, a few leaves may show mottling.
The second year, new growth is generally sparse because infected buds are
prone to winterkill. Infected vines show shortened internodes with small,
distorted leaves and sparse fruit clusters with uneven ripening. The third
year, growth is very stunted and limited to basal suckers, and the vine
eventually dies. Dead and dying vines are usually present in a roughly circular
pattern in the vineyard. The viruses are introduced into vineyards with
infected planting stock or by dispersal of seed from infected weeds. The
virus is then spread by dagger nematodes feeding on roots of infected plants.
The nematodes can retain the virus for long periods.
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| Mottling on a Riesling leaf. |
Ringlike lesion on leaf. |
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| Both
viruses infect common weeds such as dandelion, sheep sorrel, common
chickweed and red clover. Tomato ringspot virus also infects many
fruit crops. These viruses may already be present in land used to
establish new vineyards. |
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