Abstract
Apple scab, caused by the fungus Venturia inaequalis, is the major disease affecting apple production. The fungus destroys the marketability of fruit and can defoliate trees. To minimize the disease, growers apply almost weekly sprays of fungicides. A mycoparasite, Microsphaeropsis ochracea, was shown to kill the resting structures of V. inaequalis and thereby reduce disease in the subsequent crop by lowering the initial inoculum. This chapter describes the benefits and challenges in developing this fungus into a commercial product and marketing it as a sanitation and control measure.