Objective 1: Elucidate genes and mechanisms involved in postharvest pathology of fruits, such as apple (NP303, C2, PS 2b). Sub-objective 1.A. Functionally analyze 14 specific single-copy genes in Penicillium expansum using recombinant DNA technologies and evaluate mutants for defects in fruit decay, virulence, and patulin production. Sub-objective 1.B. Evaluate P. expansum mutants to inhibit and/or outcompete wild type Penicillium spp. in vitro and under controlled storage conditions. Objective 2: Develop and optimize new treatments during storage to enhance postharvest decay management of fruits. (NP303, C3, PS 3b). Sub-objective 2.A. Determine the spore holding capacity of wooden and plastic storage bins and the ability of bin inoculum to manifest in postharvest decay for stored fruit. Sub-objective 2.B: Examine and optimize new treatments to reduce fungal inoculum, combat antimicrobial resistance, and prevent rot of pome fruit during storage.