A composition containing succinate dehydrogenase inhibitor and a potentiator has been discovered to enhance the activity of the succinate dehydrogenase such that the amount of the succinate dehydrogenase inhibitor need to effectively treat a microbial substance can be reduced substantially. The compositions may be used as additives for paints and coatings, and protecting crops, seeds, wallboard, metal working fluids, wood from mold, fungi and other microbes.
