A method for controlling conidial germination and mycelial growth in fungi comprising contacting a fungal cell with an anti-fungal small molecule in an amount effective to reduce or inhibit conidial germination and mycelial growth. A method for controlling bark beetle infestations of pine trees comprising contacting one or more fungal cells with an anti-fungal small molecule in an amount effective to reduce or inhibit conidial germination and mycelial growth. The anti-fungal small molecule is 5-(p-Bromobenzylidine)-α-isopropyl-4-oxo-2-thioxo-3-thiozolidineacetic acid. The species of the fungal cell is selected from a group that has an obligate symbiosis with the mountain pine beetle (Dendroctonus ponderosae) and the western pine beetle (Dendroctonus bervicomis).