Didymella Segeticola is a new pathogen causing leaf spot disease on Zanthoxylum bungeanum

Zanthoxylum bungeanum (family Rutaceae) is an economically important deciduous shrub that is widely distributed across Asia. The leaves of this plant are rich in chemical compounds and have a variety of biological activities. However, a spot disease was discovered on Z. bungeanum leaves in Zunyi, China, in 2020. In the present study, a fungal isolate (YY-815) was obtained from Z. bungeanum leaves with leaf spot symptoms and identified as Didymella segeticola based on its morphological characteristics and phylogenetic analysis. This isolate could cause leaf spot disease and be re-isolated, fulfilling Koch's postulates. The fungicides boscalid, penthiopyrad and pydiflumetofen significantly inhibited hyphal growth of D. segeticola under in vitro conditions. This is the first study to report a leaf spot disease on Z. bungeanum caused by D. segeticola.