Pestalotiopsis trachicarpicola, a novel pathogen causes twig blight of Pinus bungeana (Pinaceae: Pinoideae) in China

Pinus bungeana is one of indigenous trees in China and widely distributed in poor and arid regions for vegetation and industrial woody use. However, since a high-incidence disease threatens the growth of mature P. bungeana tree in the garden and in the plantation every year, the overwintering shoots were infected and died in the next spring with a ratio over 70%, but the cause was beyond understood. A total of 120 fungal isolates were separated from symptomatic twigs by histological isolation methods, including Pestalotiopsis spp., Fusarium spp., Trichothecium spp., Penicillium and some unknown fungal species. Pestalotiopsis spp. was dominant, accounting for 85%. Morphological observation under microcopy showed all Pestalotiopsis species are identical, and six isolations among them were randomly selected for pathogenicity tests. Fulfilling Koch's postulates showed that all six isolates of Pestalotiopsis spp. were pathogens of twig blight, causing the same symptoms as observed in the field, while other non-Pestalotiopsis isolates were avirulent to P. bungeana twigs. Multi-gene (ITS, tub2 and TEF1) analysis and morphological observation revealed that all the six Pestalotiopsis isolates belonged to P. trachicarpicola. To our knowledge, this is the first study reporting P. trachicarpicola as the pathogens responsible for P. bungeana twig blight in China.

Automated summary

Pinus bungeana is an indigenous tree in China, widely distributed in poor and arid regions for vegetation and industrial woody use. However, a high-incidence disease threatens the growth of mature trees, with over 70% of overwintering shoots being infected and dying in the next spring. Fungal isolates from symptomatic twigs revealed that the pathogen responsible for twig blight in P. bungeana is Pestalotiopsis trachicarpicola, marking the first report of this pathogen in China.