Which of the following describes a characteristic of pathogens?

Pathogens are microorganisms that can cause disease in living organisms, including plants, animals, and humans. The characteristic of pathogens that is profoundly significant is their ability to lead to a variety of diseases in plant life. This includes a range of effects, from fungal infections to bacterial diseases, which can ultimately harm or kill plants, affecting agriculture and ecosystems. Understanding this aspect of pathogens is crucial for pest control applicators, as their role in plant health directly relates to management practices in agriculture and horticulture.

The context of other options helps clarify this understanding. Some pathogens are beneficial to plants in certain circumstances, while the idea that they are exclusively harmful to humans or that they can only exist in water is not accurate. Pathogens can inhabit various environments, both in water and on land, affecting an array of organisms and ecosystems.