The overall aim of the present study was to learn more about the prevalence, diversity, and pathogenic lifecycle of Botryosphaeriaceae species in mature avocado orchards in the main producing areas of California. The specific objectives were to (i) determine the prevalence and availability of primary and secondary sources of inocula; (ii) identify the most common species involved and assess their virulence; (iii) compare the susceptibility of unreleased avocado cultivars; (iv) study the effect of wounding on Botryosphaeriaceae seasonal infection and colonization; and (v) assess the in vitro effects of a range of temperatures and different concentrations of perseitol on pathogen mycelial growth.