Abstract

P. spp. were isolated from raspberries from several locations in the UK. The most pathogenic and widespread isolates were identified as a pathogenic form of P. megasperma, although the moderately pathogenic P. cambivora and P. citricola also caused disease outbreaks in waterlogged soil. A metalaxyl and copper nitrate mixture (Ridomil Plus) effectively controlled P. megasperma in fungicide trials. All of the widely grown British cultivars are highly susceptible to this pathogen, however useful levels of resistance have been obtained in the first generation crosses of red raspberry with Rubus spectabilis from North America. Some blackberries and tayberries are also immune.