may 2020 – april 2023
Eithne Browne
Phytophthora, the reported causal genus for root rot in European raspberry (Rubus idaeus) are oomycete pathogens which have been attributed with significant losses in productivity throughout the UK.
Recent observations suggest there may be other species of Phytophthora responsible for causing the disease other than Phytophthora rubi. The incidence of the disease across the UK and pathogenicity of these additional Phytophthora species is also unclear.
Current control strategies rely on cultural practices due to the lack of fungicide efficacy. Infection prevention is employed through securing clean planting material, maintenance of freely draining soil and sterilising irrigation lines. Infection risks have led to ~70% of UK raspberry growers moving from field to pot-based cultivation.
This project has thus far established a reliable and efficient method for DNA extraction from raspberry roots, identified a panel of root pathogens isolated from diseased raspberry plants on UK farms, and collected survey data from growers on how they manage and control root rot. This project will employ various methods of Phytophthora identification such as direct isolation, PCR and High Throughput Sequencing to determine the diversity of root pathogens in raspberry. The potential pathogenicity of these isolates will be determined in field and laboratory trials on a panel of commercially relevant varieties. Results will improve our understanding of raspberry root rot, help provide a method to produce Phytophthora-free planting material and inform growers on how best to reduce the disease.