Antagonism (phytopathology)

Antagonism (in phytopathology) occurs when one organism inhibits or slows down the growth of a plant disease-causing organism, such as harmful bacteria or fungi. Most plants can host a variety of pathogens and are often infected by multiple species simultaneously. In ecology, species competing for the same resource can influence each other in two ways: antagonism, where one pathogen harms another, and synergism, where one pathogen supports the growth of another.

Antagonism is often employed as a natural method to protect plants from diseases. This can occur through mechanism such as competition for space and nutrients, the production of toxins or siderophores by one pathogen to suppress another, induction of host resistance, or other processes that inhibit the growth or reproduction of pathogens, as demonstrated in the Ascochyta blight complex on peas.