Sensitivity of in Tennessee and North Carolina to Mefenoxam, Oxathiapiprolin, Mandipropamid, and Fluopicolide.

causes devastating disease in a range of hosts, including tobacco ( L.), tomato, citrus, strawberry, and numerous ornamentals. Black shank, caused by , is the most economically important disease to tobacco production in Tennessee and North Carolina. Black shank management includes the use of resistant cultivars, crop rotation, and fungicides. Fungicide resistance is a concern for black shank management due to the limited number of active ingredients available and the repeated exposure of pathogen populations to these products. In vitro fungicide sensitivity assays were conducted on 155 isolates collected in Tennessee and North Carolina in 2021 and 2022 to determine their EC values for oxathiapiprolin, mandipropamid, and fluopicolide. The was isolated predominantly from burley, dark, and flue-cured tobacco showing symptoms of black shank as well as tomato with buckeye rot symptoms. A discriminatory dose was used to determine each isolate's sensitivity to mefenoxam in 2021 and 2022. In 2021, EC values were determined for oxathiapiprolin, mandipropamid, and fluopicolide. In 2022, discriminatory doses based on EC values were used to determine each isolate's sensitivity to these fungicides. All isolates from the 2 years were sensitive to mefenoxam, mandipropamid, and fluopicolide. One isolate in 2022 was moderately sensitive to oxathiapiprolin, while all other isolates were sensitive.