A method for controlling conidial germination and mycelial growth in fungi comprising contacting a fungal cell with anti-fungal small molecules 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 anti-fungal small molecules in an amount effective to reduce or inhibit conidial germination and mycelial growth. The anti-fungal small molecules are 5-(p-Bromobenzylidine)-α-isopropyl-4-oxo-2-thioxo-3-thiozolidineacetic acid, 2-[5-(4-chlorobenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]-3-methylbutanoic acid, 2-[5-(4-hydroxybenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]pentanoic acid, [5-(4-isopropylbenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]acetic acid or 2-[5-(2-chlorobenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]pentanoic 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 brevicomis).
