Many strains of the virus exist, affecting many unrelated plants in different families. TMV is a very stable, persistent virus that is readily spread by human activities. TMV can be a severe problem during production of tomato transplants in greenhouses. Handling plants during standard production practices such as transplanting, tying, and pruning can effectively spread the virus. Symptoms of TMV first appear about 10 days after plants become infected.
Symptoms appear as light and dark green mottled areas on leaves.
Plants infected early in their development are stunted and have a yellowish cast. Symptoms may vary depending on virus strain, time of infection, variety, and environmental conditions. In hot weather, symptoms may not be as obvious although plants remain infected. Certain strains of TMV can cause dark, longitudinal streaks of varying lengths on stems. Affected stems are brittle and appear brown internally.