Tomato
Tobacco Mosaic Virus
TMV
Virus
In a Nutshell
- Infected leaves are distorted, with green and yellow mottling on leaves.
- Plants are stunted to varying degrees and fruit set may be severely reduced.
- Maturing fruits develop brown spots on their surface and internal brown blotches on their flesh.
Tomato
Symptoms
All plant parts can be affected during any growth stage. The symptoms depend on environmental conditions (light, day length, temperature). Infected leaves show a green and yellow mottling or a mosaic pattern. Younger leaves are slightly distorted. Older leaves show raised dark green areas. In some cases, dark necrotic streaks appear in stems and petioles. Plants are stunted to varying degrees and fruit set may be severely reduced. Unevenly ripening fruits develop brown spots on their surface, and internal, browning blotches in the fruit wall. Crop yield might be reduced significantly.
Recommendations
Organic Control
Dry heating seeds at 70°C for 4 days or at 82-85°C for 24 hours will help to rid them of the virus. Alternatively, seeds can be soaked for 15 min in a solution of 100 g/l of trisodium phosphate, rinsed thoroughly with water and dried.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. There is no effective chemical treatment against Tomato Mosaic Virus.
What caused it?
The virus can persist in plant or root debris in dry soil for periods of over 2 years (1 month in most soils). Plants get contaminated through minor wounds in roots. The virus can spread via infested seeds, seedlings, weeds, and contaminated plant parts. Wind, rain, grasshoppers, small mammals, and birds can also transport the virus between fields. Bad cultural practices during plant handling favor virus transmission, too. Day length, temperature, and light intensity, as well as plant variety and age, determine the severity of the infection.
Preventive Measures
- Use seeds from healthy plants or from certified sources.
- Use resistant or tolerant varieties.
- Use steam-pasteurization to rid your seedbed soils of the virus.
- Do not plant in fields previously infected by the virus.
- Optimize the handling of the plants by washing hands, wearing gloves and disinfecting your tools and equipment.
- Do not consume tobacco products (such as cigarettes) around tomato plants.
- Monitor seedbeds and fields, remove diseased plants and burn them.
- Find and eradicate weeds in and around the field.
- Plow and burn plant debris after harvest.
- Avoid planting alternative host plants close to tomatoes.
- Implement crop rotation with non-host crops for at least two years.
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