Abstract：
Fluazinam, a fungicide widely used in agriculture and turf management, was traditionally thought to pose a low risk of resistance. However, our in vitro sensitivity test conducted in 2021 revealed reduced sensitivity of fluazinam in dollar spot, highlighting the need for more careful field monitoring. In 2022 and 2023, we evaluated the field responses of four Clarireedia jacksonii isolates with different in vitro sensitivity to fluazinam. Fluazinam was used at a full labeled rate (0.5 oz/1,000 ft2) and a half-rate (0.25 oz/1,000 ft2) to evaluate the effectiveness of isolate-inoculated plots in the field. In 2022, natural and sensitive isolates showed significantly better control than insensitive isolates in both half- and full-rate treatments. However, in 2023, half-rate fluazinam demonstrated limited control in high disease pressure, providing relative disease control of dollar spot less than 45% across all treatments. In contrast, full-rate fluazinam maintained significantly better control of natural and sensitive isolates compared to insensitive isolates. Our results showing in vitro insensitivity leading to field insensitivity under inoculated field conditions suggest the development of fluazinam insensitivity in the C. jacksonii population. This highlights the need for judicious use of the fungicide fluazinam and the establishment of continuous resistance monitoring. Furthermore, the loss of control observed when applied at half-rates under high disease pressure highlights the importance of careful use of fungicides.
摘要：
氟尿嘧啶,一种广泛用于农业和草皮管理的杀菌剂，传统上被认为具有低抵抗风险。然而,我们在2021年进行的体外敏感性测试表明，氟嗪南在美元现货中的敏感性降低，强调需要更仔细的实地监测。在2022年和2023年，我们评估了四种对氟西南的体外敏感性不同的Clarireediajacksonii分离株的田间响应。以全标记速率（0.5oz/1,000ft2）和半速率（0.25oz/1,000ft2）使用氟西南，以评估田间隔离接种地块的有效性。2022年，在半率和全率处理中，天然和敏感分离株的控制效果明显优于不敏感分离株。然而,在2023年，半速率氟西南在高疾病压力下表现出有限的控制，在所有治疗中，提供相对疾病控制的美元点不到45%。相比之下,与不敏感的分离株相比，全率氟西南对天然和敏感的分离株保持了明显更好的控制。我们的结果表明，在接种的田间条件下，体外不敏感导致田间不敏感，这表明在杰克氏梭菌种群中，氟西南不敏感的发展。这突出了明智使用杀真菌剂氟嗪南和建立连续抗性监测的需要。此外，在高病害压力下以半速率施用时观察到的控制丧失突出了谨慎使用杀真菌剂的重要性。
