SUMMARYEpidemic attacks ofPhytophthora parasiticaon papaya fruits developed during wet, windy weather, but declined rapidly when the weather became dry. During rain, abundant sporangia were liberated from the mycelial mats on infected fruits, but none was trapped in dry air.Collar rots and tree collapse caused by root rot occur irrespective of spray treatments and previous aerial infections on the same tree: they are no more prevalent in blocks with abundant aerial infections than in blocks with none. Basal rots occurred earlier and more frequently on plantings near abandoned diseased fields: they were scattered randomly and appeared before aerial infections.It is suggested that new outbreaks might be initiated from seeds of infected fruit, in which chlamydospores have been found, or from infected nursery seedlings.Drosophilaspp. were found to be occasional vectors of sporangia.Control of aerial infections was obtained with maneb, basic copper sulphate, captan or difolatan. Spraying only the upper half of the acropetally developing fruit cluster gave much better control than spraying only the lower fruits.