Seed to store:a holistic approach to controlling internal rots in onion

Project Description
UK onion growers have invested heavily in technologically advanced drying, curing, refrigeration and controlled atmosphere storage systems designed to maintain availability of UK onions for up to 10 months, with gross annual production of around 400,000 tonnes, over 50% of UK annual consumption. The storage systems are effective in prolonging postharvest life, yet still the industry suffers from sporadic and unacceptably high incidences of internal disease. Rejection of complete lots with low levels of internal disease is a major problem. Main diseases are principally caused by Botrytis allii (neck rot) and various bacterial pathogens. Neck rot has become an increasing problem due to the recent withdrawal of thiabendazole (used as a seed dressing) in January 2010 (91/414/EEC).

In this project novel technologies are sought to address these issues, including the development of non-fungicide-based seed and set treatments as alternatives to thiabendazole, also a grower-friendly Botrytis-specific PCR/immunosensor field test to assess pathogen load and help assist managemant of the curing regime to suppress neck rot. Novel non-invasive technologies to rapidly detect internal disease in onion bulbs during grading and packing will also be researched to enable automatic rejection of internally diseased onions which cannot be seen by visual inspection.