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 .