Both Alternaria japonica and A. brassicae cause severe Alternaria leaf spot on canola (Brassica napus) and mustard (B. juncea). We tested 103 Brassicaceae varieties including 93 Australian canola, nine Indian mustard, and a single variety of Ethiopian mustard (B. carinata) under greenhouse conditions to identify host resistance to Alternaria leaf spot caused by A. japonica and A. brassicae in terms of disease incidence (percentage leaf disease incidence, %LDI), disease severity (percentage leaf area diseased, %LAD) and defoliation (percentage leaf collapse index, %LCI). Against A. japonica, across the three parameters, B. napus Surpass 404 CL was the most resistant (%LDI 7.5, %LAD 5.0, %LCI 0). Varieties Hyola 635 CC, Oscar, AG-Outback and Rottnest, with %LDI 15.6–19.4 and %LAD 12.5–15.6, also showed strong resistance, and with %LCI 10. Varieties 47C02, ATR-Signal and Clancy of B. napus showed a moderate level of resistance across %LDI (21.2–25.6) and %LAD (15.0–20.6), along with a low level of defoliation (%LCI 10). Varieties 46C03, 46C72, ATR-Cobbler and Granite TT of B. napus also showed a moderate level of resistance, with %LDI 23.1–28.7, %LAD 18.1–20.6 and %LCI 11.2–14.4. The significance of this resistance against A. japonica is highlighted by the severe disease on B. napus Thunder TT (%LDI 78.8, %LAD 72.5, %LCI 47.5). Against A. brassicae, all varieties showed susceptibility; however, B. napus ATR-Grace was the least susceptible in relation to disease incidence (%LDI 41.2) and severity (%LAD 36.2), and B. napus Hyola 450 TT the most susceptible (%LDI 90.0, %LAD 82.5). Variety Hurricane of B. napus was the least susceptible in terms of consequent defoliation (%LCI 11.2) and B. napus CBTM Tribune the most susceptible (%LCI 81.2). The B. carinata variety BCA 1 (ATC 95065) and all test B. juncea varieties showed susceptibility to both pathogens. These findings demonstrate high levels of resistance across Australian canola varieties against A. japonica that can be directly deployed where A. japonica is important and can be utilised by breeders for improving resistance in future varieties. By contrast, susceptibility across Australian canola and mustard varieties to A. brassicae is concerning, highlighting a need to locate suitable resistances and, until effective host resistance can be located, to develop and deploy cultural and chemical options.

交链孢霉和芸苔属均在芥花油菜（芥菜）和芥菜（芥菜）上引起严重的交链孢霉叶斑。我们测试了103个十字花科品种，包括93澳大利亚卡诺拉，九个印度芥末，和一个单一的各种埃塞俄比亚芥（的芥温室条件下），以识别所造成的链格孢叶斑病宿主抗性A.粳稻和A.甘蓝在疾病方面发病率（叶片疾病发病率百分比，LDI），疾病严重程度（患病叶片面积百分比，LAD）和脱叶率（叶片塌陷率百分比，LCI）。针对A. japonica，通过三个参数，B. napus Surpass 404 CL的抵抗力最高（％LDI 7.5，％LAD 5.0，％LCI 0）。品种Hyola 635 CC，奥斯卡，AG-内陆和罗特尼，用％LDI 15.6-19.4和％LAD 12.5-15.6，也表现出较强的阻力，并用％LCI 10.品种47C02，的ATR信号和克兰西欧洲油菜显示在％LDI（21.2–25.6）和％LAD（15.0–20.6）上有中等水平的抵抗力，而低水平的落叶（％LCI 10）。甘蓝型油菜的品种46C03、46C72，ATR-Cobbler和Granite TT也显示出中等水平的抗性，％LDI 23.1-28.7，％LAD 18.1-20.6和％LCI 11.2-14.4。这种对日本粳稻的抗性的重要性已通过严重的甘蓝型油菜雷霆TT（％LDI 78.8，％LAD 72.5，％LCI 47.5）疾病突出显示。反对甘蓝型油菜，所有品种均表现出易感性。然而，欧洲油菜ATR-格雷斯相对于发病率（％LDI 41.2）和严重程度（％LAD 36.2）的至少易感，和欧洲油菜Hyola 450 TT最易感（％LDI 90.0，％82.5 LAD）。就随后的落叶（％LCI 11.2）而言，欧洲油菜品种飓风最不敏感，而最容易受到油菜品种CBTM Tribune影响（％LCI 81.2）。的芥各种BCA 1（ATC 95065）和所有测试芥菜品种表现出易感性两种病原体。这些发现表明，澳大利亚双低油菜品种对粳稻的抗药性较高。可以直接部署在重要的日本粳稻上，育种者可以利用它来提高未来品种的抗性。相比之下，澳大利亚油菜和芥菜品种对油菜曲霉的易感性令人担忧，这突出表明需要找到合适的抗性，直到找到有效的寄主抗性，才能开发和部署文化和化学选择。