Co-infection of sp. nov. and Causing Stem Rot in in China.

() (Araceae) is an evergreen herbage, which is intensively grown as an ornamental plant in South China. A new disease was observed in from 2020 to 2021 in Guangdong province, China. The disease symptoms associated with plants were initial leaf wilt, stem rot, and resulting plant death, leading to severe economic losses. In total, six isolates were obtained from diseased plants. The putative pathogen was identified using both morphological characteristics and molecular phylogenetic analysis of calmodulin A (), RNA polymerase largest subunit 1 (), RNA polymerase II (), translation elongation factor-1α (α), and beta-tubulin (β) sequences. Two species were identified, namely, one new species, () belonging to species complex. In addition, () belonging to the () species complex was also identified. Pathogenicity assays were conducted by inoculating each species into potted plants and co-inoculating two species. The results showed that two species could infect plants independently and can infect them together. Co-infection of these two species enhanced the disease severity of . Compared to single inoculation of , severity was higher and disease development was quicker when plants were only inoculated with . In addition, these two species could infect plants without wounds, while inoculation with a physical injury increased disease severity. This is the first report of co-infection by and causing stem rot on worldwide. This study will be an addition to the knowledge of diseases in ornamental plants. These results will provide a baseline to identify and control diseases associated with