Integrated management of lettuce downy mildew (CP 186)

Bremia lactucae is an obligate biotrophic oomycete causing downy mildew on lettuce, reducing yield and quality, particularly in cooler growing environments.  Information exists on the epidemiology of the disease and environmental requirements for infection, spore production and transmission.  Integrated management strategies should include host resistance, fungicides, cultural control, and disease forecasting where possible.  A robust downy mildew management package is a high priority for the horticultural industry in the UK.  To inform the appropriate use of control measures to manage the disease it is important to understand variability within the B. lactucae pathogen population and to associate molecular markers with phenotype.  Useful markers are currently lacking for B. lactucae and the main aim of this project is to capitalise on the availability of genome sequences to develop and use neutral and/or functional molecular markers to examine population diversity in B. lactucae populations in the UK and to link this diversity to phenotypic characteristics, including pathogen race, as measured using internationally agreed differential host genotypes of lettuce, fungicide sensitivity, geographic location and lettuce variety and other important parameters. 

This work is designed to form the basis of a future lettuce downy mildew national outbreak information service for growers and to link with work on in-field spore detection and disease forecasting conducted elsewhere to form a joined up programme of research towards the aim of a comprehensive IPM approach for the disease. 

Develop neutral markers (e.g. SSR markers as previously developed for P.infestans) and/or functional markers  (linked for example to virulence phenotype) to form the  basis of an integrated  management  system for lettuce downy mildew with the aim of providing a future disease outbreak service.