ep·i·phy·tol·o·gy \ˌepəˌfīˈtäləjē\noun (-es) Etymology:epiphytotic + -ology 1.: a science that deals with character, ecology, and causes of outbreak of plant diseases especially of epiphytotic nature 2.: the sum of the factors controlling the presence or absence of a disease or pathogen of plants < aspects of epiphytology and control of tomato fruit rot >