Cause Tomato mosaic virus (most commonly) or Tobacco mosaic virus, which also affects pepper, eggplant, petunia, and many other solanaceous plants. The virus spreads readily by workers' hands, equipment, and clothing. It persists in infected plant residue and may be on seed.
Symptoms Symptoms depend on the virus strain. Often, foliage mottles with alternating light and dark green areas. New leaflets curl and are slightly malformed. More severely affected leaves are badly distorted and rather fern-like. Plants usually are somewhat stunted and bear few fruit if infected when young. Plants and fruit are not much smaller if plants are infected after they reach fruiting stage. Occasionally necrotic spots or streaks develop on stems and leaves. Sometimes fruit ripens unevenly, or the fruit wall turns brown internally.
- Use resistant varieties.
- Use healthy transplants and pathogen-free seed.
- Wash hands with soap and water before handling plants.
- Disinfect equipment.
- Use clean soil each year in seedbeds, or sterilize old soil.
- Do not plant in a field with infected debris.
- Do not smoke while handling tomato plants.