Diaporthe actinidiicola: A novel species causing branch canker or dieback of fruit trees in Henan Province, China

Pear (Pyrus), walnut (Juglans) and kiwifruit (Actinidia) are important cash crops in China. Recently, symptoms of branch canker or dieback have been frequently observed in many orchards in Henan Province and have resulted in high losses of fruit production. In this study, symptomatic branches were collected for aetiological isolation from three hosts during 2020 and 2021. Seven isolates from these hosts were identified as one novel species, based on morphological characteristics and phylogenetic analyses of the concatenated sequences of the internal transcribed spacer of the ribosomal DNA (ITS), translation elongation factor 1α (TEF), β‐tubulin (TUB), histone (HIS) and calmodulin (CAL). We proposed the name Diaporthe actinidiicola and completed Koch's postulates to confirm pathogenicity. Host range evaluation indicated that D. actinidiicola could infect all inoculated fruit trees (pear, kiwifruit, walnut, apple [Malus] and peach [Prunus]) and the isolates from different hosts were most virulent on their original host. This study characterizes a novel Diaporthe species from three different hosts in China and contributes useful data for practicable disease management. The novel species of Diaporthe actinidiicola can cause branch canker or dieback of walnut, pear and kiwifruit, resulting in fruit yield reduction.