The rice pathogen, Magnaporthe oryzae, undergoes a complex developmental process leading to formation of an appressorium prior to plant infection. In an effort to better understand phosphoregulation during appressorium development, a mass spectrometry-based study was undertaken. Phosphosites were identified from phosphoproteins from mycelia, conidia, germlings, and appressoria of the wild type and a ckpA mutant. The cyclic-AMP dependent protein kinase A (CPKA) is required for initial perception of the leaf surface, development of functional appressoria, and timely mobilization of storage reserves in conidia, including glycogen and lipid bodies.