PROBLEM TO BE SOLVED: To obtain the subject plant disease-controlling agent against a variety of pathogenic filamentous fungi of plant diseases, particularly that can safely control fungal diseases of black mulberry (sycamine) trees by using a culture product of a specific microorganism as an active ingredient.
SOLUTION: The objective plant disease-controlling agent is obtained by using, as an active ingredient, the culture mixture of a microorganism that belongs to Bacillus amyloliquefaciens and produces a substance inhibiting the growth of plant disease pathogenic fungi. This microorganism is preferably Bacillus amyloliquefaciens RC-2 strain deposited as FERM P-16641. This microorganism can be aerobically cultured in a similar manner to that for known aerobic bacteria. This culture mixture is centrifuged to remove the solid components and the remaining supernatant is applied to the plants. The plant diseases to be controlled are, for example, anthracnose, white root-rot and the like in plants as mulberry tree and the like.