This invention provides wallboard with a gypsum core with improved antifungal properties based on the distribution of fungicide and starch. Preferably, the wallboard has a gypsum core having a first surface and a second surface; facing sheets adhered to the first and second surfaces; a fungicide and a starch in the gypsum core; wherein the concentration of fungicide and starch is greater in portions of the core adjacent to the facing sheets than in a center of the core. Also a method for manufacturing wallboard as described above.