How do tobacco, insects, and seeds contribute to plant diseases?

Tobacco, insects, and seeds can significantly contribute to the spread of plant diseases, particularly through the transmission of viruses. Certain insects, such as aphids or whiteflies, are known vectors that carry viral pathogens from infected plants to healthy ones, facilitating rapid outbreaks of disease within crops. Tobacco plants can also harbor specific viruses that can be transmitted during handling or by tools that have contacted infected tissue. Seeds, when infected with viruses, can serve as a source of infection for newly germinating plants, perpetuating the cycle of disease in a population.

While nourishment and protection from pests are essential functions in plant health, they do not directly relate to how these factors specifically contribute to plant diseases. Photosynthesis is a critical process for plants but is not part of the dynamic that leads to plant diseases associated with tobacco, insects, or seeds. Therefore, the focus on the role of these elements in spreading viruses directly addresses how they contribute to the prevalence of plant diseases.