The invention relates to an agent for treating and/or preventing fire blight, particularly present in wood and fruit trees, comprising formic acid and/or a salt of formic acid, particularly calcium formiate as an active component. Further disclosed is the use of formic acid and/or a salt of formic acid, particularly calcium formiate as an active component in herbicides, particularly for treating and/or preventing fire blight, and the use of formic acid and/or a salt of formic acid, particularly calcium formiate, for the production of an agent for treating and/or preventing fire blight.
