Characterization and pathogenicity of Diplodia seriata causing branch canker on Pinus pinea in Tunisia

Abstract

Several species of Botryosphaeriaceae family are among the most aggressive pathogens associated with botryosphaeria dieback of agricultural and forestry trees. Particularly, Diplodia spp. having a cosmopolitan distribution, are well-known as virulent of woody plant hosts including Pinus spp. In recent years, symptoms of canopy wilt, branch dieback, necrosis, and trunk cankers have been noticed on Pinus pinea trees in Tunisian forests. However, this has been less welldocumented in North Africa and especially in Tunisia. The aim of this study is to characterize the causal agent of P. pinea dieback in northeastern Tunisian forest. A collection of thirty-eight isolates obtained from symptomatic branches of P. pinea trees was identified as Diplodia seriata by means of morphological characteristics, and phylogenetic analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA. A pathogenicity test was conducted on 3-years-old P. pinea seedlings, confirmed the virulence of the fungus. To the best of our knowledge, this is the first record of D. seriata associated with branch canker on P. pinea in Tunisia.