When can viruses enter plants?

Viruses can enter plants primarily through specific entry points, and one of the most common methods is through pollination or wounds. When a plant experiences injury, whether from mechanical damage, insect feeding, or even physical cuts, the disrupted tissues can create openings where viruses can infiltrate. Additionally, during the process of pollination, if a virus is present on the pollen or the pollinator, it can be transmitted to the plant.

The idea that viruses can only enter during the seedling stage is too restrictive, as viruses can infect plants at any growth stage. Similarly, the notion that viruses can only enter through healthy tissues is inaccurate, since healthy tissues are typically resistant to infection. Heavy rainfall can create conditions that favor certain pests or pathogens, but it's not a direct entry route for viruses. Hence, the most accurate understanding is that viruses invade through wounds or during the pollination process.