No evidence that seed is a pathway for this pathogen. There were no references found indicating that seed is a pathway for Leptosphaeria libanotis. Seed has been implicated as a pathway for its asexual stage, Phoma rostrupii, in Russia and surrounding areas (RICH ISTA). However, no original references have been found to support these claims. Until original references are found, these statements are considered unsupported and seed is not considered to be a pathway for this fungus in carrot.
Zhao, P., Crous, P. W., Hou, L. W., Duan, W. J., Cai, L., Ma, Z. Y., & Liu, F. (2021). Fungi of quarantine concern for China I: Dothideomycetes. Persoonia-Molecular Phylogeny and Evolution of Fungi, 47(1), 45-105.