What is the function of a pathogen?

A pathogen is an organism, such as a bacterium, virus, or fungus, that can cause disease in its host, which is often a plant or an animal. The primary role of a pathogen is to invade the host, replicate, and disrupt normal biological processes, often leading to symptoms such as wilting, necrosis, or reduced growth. This ability to cause disease influences ecosystems, agriculture, and the management of crops and natural resources.

In the context of aquatic environments, understanding the function of pathogens is crucial, especially for controlling unwanted plant species. While promoting plant growth or enhancing nutrient availability represents beneficial processes typically associated with some organisms or practices, pathogens operate from a different perspective, focusing on causing harm rather than supporting host health. This distinction is essential in aquatic weed control, where understanding the dynamics of plant diseases can inform management strategies to control invasive or unwanted plant species.