Phytophthora cinnamomi in the Brisbane Ranges: Patterns of Disease Extension

Abstract

Three patterns of disease extension were observed in areas of uncultivated shrubby dry sclerophyll forest invaded by the pathogen Phytophthora cinnamomi. Environmental factors were found to determine which pattern developed. Where inoculum was spread downhill with drainage water, diseased areas were separated by clearly defined boundaries from unaffected vegetation. Where disease extension occurred uphill through soil or from root to root, a wavy boundary marked the active disease front. Investigations showed that absence of disease extension for 4 years in highly susceptible vegetation may be associated with differences in soil characteristics.