Globally, onions are the second-most popular vegetable, with production at 99Mt p.a. In the UK, they are the fourth-most consumed vegetable and growing in popularity, given recent resurgences in the perceived health benefits of eating vegetables and enthusiasm for home cooking. Whilst it might be anticipated that the UK onion industry (based primarily in eastern England), would be thriving, this is not the case. Home-onion production fulfils less than half of the UK's demand (≈800kt p.a.), with the deficit made up by imports over approximately three months, associated with greater-environmental impact and higher-overall prices. The situation has been exasperated by recent-hot summers, seeing onions go unirrigated in favour of other crops, resulting in a 20%-yield reduction. Defra anticipates this trend to continue and growers are under intense pressure to increase productivity and regain import trade and in so doing, reduce waste, crop-input losses and transport impacts in a transition to net-zero production. **Our vision** is to allow UK growers to grow, store and supply onions to the UK market all-year-around. Improved-crop quality is key to increased productivity, with bacterial infections being the greatest cause of crop- and storage-failures, economic losses (£8.5M p.a. farm-gate losses) and reputational damage. 'Allium Protect' follows a recent IUK SMART project, which detailed the main onion-rot bacteria and generated proof-of-concept for an **innovative, bacteriophage-based solution**; naturally-occurring, highly-specific bacterial viruses, with zero non-target effects. Bacteriophage form the basis of a low-risk biocontrol and are being pioneered by the Project Lead as Plant-Protection Products in key fresh-produce sectors. Allium Protect's **key objectives** are to build on the SMART data, addressing new **scientific- and technological-challenges** and assessing the technology's **feasibility** within **commercial-onion growing**. English growers are central to the project, led by Rix Farms/Stourgarden, producing 20% of the UK's onion crop and supplying ≈90kt for retail (including 100% Tesco's requirements). 'Allium Protect' **aims** to optimise a pilot-bacteriophage mix from the earlier SMART project, assess its efficacy in preventing crops from field-infections and subsequent in-store breakdown. Key academic knowledge exchange will detail the full onion-growing environment microbiome and any impacts of bacteriophage on the dynamics within it. Success will provide confidence to invest in further R&D and exploitation towards full-commercialisation. The project addresses a timely opportunity given the impact of rot-induced losses on the UK onion industry. It also represents a significant opportunity for the Lead Application to reinforce its position as a major player in a rapidly-growing, global-biopesticide market.

Fusarium basal rot (FBR) is a disease caused by the soil-borne fungus Fusarium oxysporum f. sp. cepae (FOC) that infects the roots and basal plate of onions leading to severe pre- and postharvest losses. Onions can become infected with FOC at any time during crop growth, but the biggest losses occur after harvest when asymptomatic bulbs extensively rot in store. Entire stores can be lost if disease levels rise above \>10-15% since it is unfeasible to rogue out infected bulbs. FOC is an increasing problem for UK onion growers due to climate warming, with warmer wetter summers favouring disease development. Critically, there are no effective control options and annual UK crop losses are increasing, leading to contraction of the industry in terms of both land plated and grower numbers. The industry desperately needs ways to assess FBR risk and manage the disease at different production stages, and as early as possible, to reduce losses. We have assembled a multidisciplinary team to implement novel detection and control approaches to FBR. The team's expertise spans remote sensing, onion agronomy, laboratory science and fundamental biology, enabling us to follow a holistic approach that covers the onion production from soil to store. This affords maximum flexibility and adaptability to provide a range of solutions including: \*A molecular diagnostic tool to measure Fusarium levels in soil and assess the risk of FBR pre-planting. \*Enhanced knowledge of agronomic factors affecting FBR expression and field-level management options to control FBR. \*A vision system to early detect FBR-infected onions in the field and during harvest. \*Smell-based sensor technologies to detect FBR-infected onions in early stages of storage. We intend to provide UK onion growers with a suite of FBR monitoring and mitigation options with the potential to reduce the prevalence of FBR by 50%. The anticipated impact of our project will be reducing the \>£10M annual losses due to FBR, and hence substantially improve the long-term productivity and resilience of the sector. This will give growers confidence to expand planted area and, in turn, allow the UK to reduce reliance on some of the ~300,000 tonnes of bulb onions that are currently imported annually. Reducing waste from FBR-infected onions will also improve sustainability of the industry by ensuring that financially valuable and carbon-intensive inputs for onion production are not lost.

Standard growing practices for field crops such as alliums must be updated to overcome challenges presented by climate change and the increasing prevalence of soil-borne diseases. Onions (the main focus of this project) are a staple for UK households - in constant demand throughout the year as a foundation ingredient in dishes prepared by families across the nation. Onions are susceptible to diseases such as Fusarium, white rot, neck rot, and downy mildew, and land used for growing onions can only support their growth for one in every six/seven years, as any traces of plant matter left in the ground post-harvest can lead to re-infection. It is becoming increasingly difficult to secure suitable 'clean' land for farming onions to meet demand. Alongside land pressures, farmers are being urged to contribute to improving UK food security and reducing food miles by growing more produce locally. One approach to addressing land scarcity, reducing CO2-heavy inputs, and better controlling disease in the growing of onions is to move this traditional 'field crop' into a CE. **Aeroallium** Through this project, Stourgarden will be the first UK growers to test the viability of protected growing for onions on a commercial scale. We anticipate the following benefits flowing from the development of a CE system for onions: -Reduction in water use through capture and recycling -Avoid infection of soil borne diseases such as Fusarium -Significant reduction of nutrient inputs, and elimination of any risk of nutrient run-off impacting waterways and ecosystems -Removal of the need for heavy farm machinery for growing and harvesting processes -Increased automation leading to decreased reliance on low-skilled labour, with new, skilled technical and engineering roles created as Stourgarden develops its CE capability -Significant reduction in land pressure - freeing up land for growing other crops, enabling land to be rested more often, improving soil quality and rewilding margins -Remove reliance on importing onions to cover gaps in the UK growing season (vastly reducing transport-related emissions and improving the UK's trading position) -Remove impact from climate change-related adverse weather during the growing season, which can typically affect crop yield by up to 30% -More reliable crop will deliver supply chain security for retailers and households -Reducing need for cultivation of soil which releases significant amounts of stored carbon -Increased company profitability and growth in sector with traditionally low margins, and thus gains for the regional economy and UK Plc

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.