New York State ranks second only to Washington State in apple production in the United States, its ~600 growers responsible for about 13% of the nation’s supply; over half of which is destined for the fresh market. Apple powdery mildew (caused by the fungus Podosphaera leucotricha) is endemic in production regions statewide. Left unmanaged, the disease renders fruit unmarketable due either to flower bud malformation or fruit russet damage and negatively impacts tree vigor by colonization of the host trees’ foliar tissues. Currently, the disease is not of extreme concern in New York compared to the rapidity with which other diseases – namely apple scab and fire blight – may devastate an orchard. However, long-term observations of the northeast’s shifting climate indicates that the environment of the state’s production regions will likely become more conducive to survival, development, and spread of P. leucotricha in coming decades. In the absence of durable host resistance, commercial producers rely on fungicide programs to manage apple powdery mildew. Misuse of single-site fungicides with specific modes of action, however, may lead to resistance selection in populations of P. leucotricha and render these limited tools ineffective. The first goal of this research evaluated a series of fungicide programs timing applications to weather thresholds conducive to development of P. leucotricha. This work demonstrated that said programs managed apple powdery mildew just as well as a standard “calendar-interval” program while using significantly fewer fungicide inputs. The second goal of this work was to determine whether the demethylation inhibitor (DMI) fungicide class remained viable for apple powdery mildew management. We found that DMIs indeed were still effective despite their historical widespread use in fungicide programs statewide and resistance development in the fungus Venturia inaequalis, which P. leucotricha is co-managed with. The third goal was to conduct a thorough survey of commercial orchards statewide and assess collected samples for mutations in genes (CYP51, cytb, and sdhB) known to confer fungicide resistance in P. leucotricha. We found no evidence of such mutations nor observed control failures in orchards, indicating that these single-site chemistries should remain useful for future growing seasons with proper rotation. The work completed in this dissertation contributes to the continued management of apple powdery mildew in New York State.