Establishment of a Detached Leaf Pathogenicity Assay for Pepper Anthracnose

Pepper anthracnose, caused by Colletotrichum scovillei, is one of the most destructive diseases threatening pepper production in Korea. Detached pepper fruits are commonly used for pathogenicity assays; however, obtaining fruits through plant cultivation requires substantial time and labor. Although commercial fruits can serve as alternatives, essential meta-information—such as cultivar, post-harvest storage duration, and potential chemical residues—is typically unavailable, often resulting in non-reproducible pathogenicity assay outcomes. To address this limitation, we developed a detached leaf pathogenicity assay that offers applicability and consistency comparable to the fruit assay. Using 3-week-old pepper seedlings, we evaluated the effects of conidial suspension concentration, temperature, and incubation period on the pathogenicity of C. scovillei. Under optimal conditions of a 10<sup>6</sup> spores/ml conidial suspension, incubation at 25 o C, and evaluation at 7 days post inoculation, the detached leaf assay showed no statistically significant differences from the fruit assay. We further assessed its feasibility for fungicide efficacy testing by examining the effects of fungicide concentration and spray timing on control efficacy. Taken together, these results support the detached leaf assay as an efficient and reproducible alternative to the fruit assay for evaluating the pathogenicity of C. scovillei.