Integrated control of Sclerotinia disease in celery and lettuce

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The soilborne plant pathogenic fungus Sclerotinia sclerotiorum causes stem and crown rots on a range of important horticultural crop plants such as beans, brassica, carrots, celery, lettuce and potatoes, resulting in major economic losses globally. Infection is initiated by airborne ascospores released from mushroom-like apothecia which are produced by soilborne survival structures known as sclerotia. Disease control is primarily focused on preventing ascospore infection through application of fungicides but this approach is becoming increasingly undesirable. The number of S. sclerotiorum sclerotia also continues to build up in many soils, resulting in increased disease pressure and presenting a major long-term challenge for growers. However, little attention is given to reducing this primary inoculum as part of a more sustainable disease management strategy. This is very much the case for intensive vegetable production systems such as in southern Spain where celery and lettuce are grown by Gs Growers as a large part of their business to ensure year-round availability for the UK. Losses due to Sclerotinia in lettuce in these areas averages at least 10% and in severe cases more than 50%. The importance of Spanish production for both UK suppliers and consumers has recently been highlighted through the recent 'lettuce crisis' where adverse weather disrupted supplies. The main aim of this project is to develop methods for reducing the impact of Sclerotinia disease by reducing sclerotial survival and viability. The main objectives are to 1) collect, identify and characterise Spanish S. sclerotiorum isolates using molecular genotyping to compare with existing data for UK isolates, 2) determine environmental conditions required for sclerotial germination of Spanish isolates compared to UK isolates, 3) determine efficacy of different soil treatments including (bio) solarisation, biofumigation, anaerobic disinfestation and biological control agents. G's Growers are one of Europe's leading family-owned fresh produce companies and a major producer of celery and lettuce. Although the student will be based in at the University of Warwick, they will have a unique opportunity to spend a significant amount of time in Spain embedded in the G's business and carrying out field based research. The studentship will therefore suit an individual who wants to learn from both academia and commercial environments, is keen to see their research put into practice and envisages a career at the interface between agricultural practice and research. The project will therefore combine high quality science with real-world agronomy and includes aspects of plant pathology, soil science and agronomy.