Pulses, in particular peas and broad beans, are important crops both in the UK and worldwide and they are grown as extensive monocultures. Even with long rotations, the crops are vulnerable to major epidemics of economically important pests and diseases, of which downy mildews (caused by the oomycete biotrophic pathogens Peronospora viciae f. sp. pisi (Pvp) and P. viciae f. sp. fabae (Pvf) in peas and beans, respectively) are the most serious. Breeding companies are challenged to produce cultivars with new resistance genes and will benefit from access to crop wild relatives carrying new resistance genes. The disease is managed through deployment of resistant varieties and chemical controls; however a lack of information on prevalent isolates can lead to serious yield losses in crops grown on contaminated sites through uninformed variety selection. Although a differential set of plant cultivars is available to identify the virulence genes in pathotypes of Pvp/Pvf, the test is too time-consuming to be of immediate use to commercial growers and does not allow rapid monitoring of the prevailing isolates. In addition, generating a model for pathogen spread is impossible using current methods. The problem is exacerbated by reports of resistance of oomycete pathogens to pesticides such as metelaxhyl. Without adequate control regimes, pea and broad bean production will incur greater crop wastage and it is therefore imperative that methods are developed to decrease growers' reliance on pesticides for the control of downy mildew. Deployment of pulse cultivars resistant to prevailing isolates is the most promising approach. Use of appropriate molecular tools will enable breeders, epidemiologists, modellers and growers to: a) identify the prevailing virulent isolate; b) investigate the epidemics of disease; c) monitor pathogen movement and d) deploy the appropriate cultivar(s) resistant to the prevailing isolate rapidly and thus control the disease in an environmentally friendly and sustainable manner. Accurate advice to growers about resistant cultivars requires correct information on the virulence of Pvp/Pvf races within the locality. However, diagnosing the pathogen at the isolate level requires the right tools. The innovative approach described in this project focuses on the development of molecular tools for accurate identification of Pvp/Pvf isolates as well as for breeding for resistance. We aim to identify new resistance sources to include in breeding programmes and develop molecular markers to enable rapid identification and monitoring of pathogen isolates. We will use next generation sequencing to identify polymorphisms in several isolates. These polymorphisms will then be utilised to generate isolate-specific markers. Once identified, markers will be tested under laboratory conditions and subsequently will also be checked in commercial fields. In addition, we will use biological control agents to control downy mildew disease. These will lead to increased crop productivity, reduced reliance on pesticides and less wastage from diseased plants.