Economic impacts of Xylella fastidiosa on the Australian wine grape and wine-making industries

Overview \r\nXylella fastidiosa is a bacterium that affects many plant species. In Brazil X. fastidiosa infects an estimated 200 million citrus trees. In California, it causes over $100 million in yearly losses to the grape industry. And on the Italian peninsula of Salento, around one million olive trees are estimated to be infected. There is no cure for the disease. \r\n\r\n Recent outbreaks in Europe prompted Australia's biosecurity authorities to introduce emergency measures in late 2015 to reduce the risk of an incursion. As part of the heightened preparedness, the Department's Plant Biosecurity Division requested ABARES to assess the economic impacts of a potential X. fastidiosa outbreak on the wine grape and wine-making industries in Australia. \r\n\r\n ABARES assessed a range of scenarios and the expected benefits to the wine industry of keeping Australia free of X. fastidiosa and its vectors. Three scenarios of progressively smaller habitat suitability were assessed: \r\n• Scenario 1 - all existing wine grape growing areas \r\n• Scenario 2 - Scenario 1 areas with an average minimum winter temperature above 1.7 degrees C, and \r\n• Scenario 3 - Scenario 2 areas that were in close proximity to riparian vegetation. \r\n\r\n ABARES estimated that if it enters and establishes in Australia, X. fastidiosa could cost the Australian grape vine industries between $2.8 billion to $7.9 billion, over 50 years, on a net present value (NPV) basis. ABARES also found that if X. fastidiosa appears in a region but was contained within that region, the aggregate impact on the wine industry would be a fraction of the impact of an uncontrolled spread. Containing the outbreak to either the Murray Darling - Swan Hill or Lower Murray regions, for example, could avoid losses estimated between $2.6 billion and $2.0 billion, on a NPV basis. \r\n\r\nKey Issues \r\n• X. fastidiosa is not present in Australia, but is a major concern. \r\n• If it established in Australia, X. fastidiosa would pose a significant threat to the productivity, sustainability and competitiveness of Australia's wine industry. \r\n• Habitat suitability in Australia is likely to be high. \r\n• The current level of investment in prevention measures to reduce the risk of X. fastidiosa entering Australia appear to be highly cost-effective. \r\n• International experience suggests that successful eradication is unlikely. Nonetheless, were it to enter, enhancing early detection capacity would be prudent. \r\n\r\n概述 苛养木杆菌（Xylella fastidiosa）是一种可侵染多种植物物种的病原菌。在巴西，据估算已有2亿株柑橘树被该病原菌侵染；在美国加利福尼亚州，其每年给葡萄产业造成逾1亿美元的经济损失；在意大利萨伦托半岛，约100万株橄榄树被估算已受侵染。目前该病害尚无有效防治方案。 近期欧洲暴发的疫情促使澳大利亚生物安全监管机构于2015年末出台紧急防控措施，以降低病原菌入侵风险。作为强化防控准备的举措之一，澳大利亚农业部植物生物安全局请求ABARES评估潜在的苛养木杆菌暴发对澳大利亚酿酒葡萄及葡萄酒产业带来的经济影响。 ABARES评估了多种情景，以及维持澳大利亚无苛养木杆菌及其传播媒介状态可为葡萄酒产业带来的预期收益。本次评估共设置3种生境适宜性逐步降低的情景： • 情景1：所有现有酿酒葡萄种植区 • 情景2：在情景1的区域基础上，筛选冬季平均最低气温高于1.7摄氏度的区域 • 情景3：在情景2的区域基础上，筛选紧邻河岸植被的区域 ABARES估算，若苛养木杆菌入侵并定殖澳大利亚，以50年周期的净现值（NPV）计算，澳大利亚葡萄产业将蒙受28亿至79亿美元的经济损失。ABARES同时发现，若该病原菌仅在单个区域出现并得到有效管控，其对葡萄酒产业的总体影响仅为无限制扩散时的极小一部分。例如，若将疫情管控在墨累达令-天鹅山（Murray Darling - Swan Hill）或下墨累（Lower Murray）区域，以净现值计算可避免约20亿至26亿美元的经济损失。 核心议题 • 苛养木杆菌目前尚未在澳大利亚境内发现，但仍是极具威胁的防控对象。 • 若该病原菌在澳大利亚定殖，将对澳大利亚葡萄酒产业的生产效率、可持续性与竞争力构成严重威胁。 • 澳大利亚境内的病原菌生境适宜性大概率较高。 • 当前为降低苛养木杆菌入侵风险所投入的防控措施，性价比极高。 • 国际防控经验表明，彻底根除该病原菌的难度极大。即便如此，若病原菌入侵，提升早期检测能力仍是审慎之举。