Morphological and Phylogenetic Resolution of Diplodia neojuniperi Emerging Diplodia Top Dieback of Pinus thunbergii Parl. in China

Abstract

In Bazhong City, Sichuan Province, China, top dieback symptoms were found on many pine trees (Pinus thunbergii Parl). The tips of old needles first turned grayish-green and then developed into brown bands in the field. Phylogenetic analysis of concatenated ITS and EF1-α indicated the pathogen of this dieback disease as Diplodia neojuniperi. Additionally, effects of temperature, pH and medium on the mycelial growth were also characterized. The most favorable temperature and pH level for mycelial growth are 25°C and 8, respectively. The optimal medium for mycelial growth is PDA medium. To our knowledge, this is the first report of D. neojuniperi causes Diplodia top dieback on Pinus thunbergii. Our results provide fundamental information for monitoring and preventing such disease in the future.

A New Species of Biscogniauxia Associated with Pine Needle Blight on Pinus thunbergii in China

“…This is the first report that the new species identified here is associated with discolored and withered needles on P. thunbergii in forest. The symptoms have affected the potential value of pine trees, influenced the balance of the forest environment, and caused consequential economic and ecological losses [10].…”

“…The disinfected material was removed using a sterilized scalpel, and disease/health junction parts were cut into 2-3 × 2-3 mm blocks. These tissue blocks were cultivated on 2% potato dextrose agar medium (PDA) and incubated at 25 °C without light [10]. Conidia were removed from colonies with a needle, and pure cultures were obtained by single spore isolation using serial dilution techniques [11].…”