Definition - What does Pathogen mean?
A pathogen is an infectious agent that disrupts the normal functioning capabilities of a healthy vine. Types of pathogens include, diseases, bacterial infections, fungal infections, viruses that all cause damage and can spread from one vine to another. Pathogens in plants can cause root or stem rot, wilted fruit and leaves, cankers and blights.
WineFrog explains Pathogen
Plant pathogens that are present in grapevines are typically parasitic (live off the vine) and they either take shelter in the vine or use it as food or both. These parasitic pathogens from bacteria like fungi or viral are spread from one vine to another by rain, wind, overhead irrigation or movement (like driving or walking) through the vineyard.
The bacteria can enter the vine through natural openings in the leaves, wounds that haven’t healed and occasionally in the roots or stems (even though the wooden texture of these parts are harder to penetrate).
The bacteria can survive inside the plant or in the vineyard on infected plants, infected soil or debris/equipment that is used in the vineyard which spreads bacteria. They can be treated with antibiotics or fungicides that kill the pathogen but may harm the host vine as well.