First Report of Olive Branch Dieback in Croatia Caused by Cytospora pruinosa Défago

Abstract

Olive (Olea europaea L.) is a very important crop grown in the Mediterranean part of Croatia. Olive branch and fruit dieback symptoms were observed in two olive orchards in Istria, Croatia. The samples from symptomatic trees were collected and brought to the laboratory for analysis. Based on their morphological characterization, isolated fungi were identified as Cytospora sp. Two representative isolates (one per orchard) were taken for molecular analysis, and based on DNA sequence data of the ITS and TUB gene regions, and phylogenetic analysis of the sequences, the isolates were identified as Cytospora pruinosa Défago. To determine pathogenicity, pathogenicity tests were conducted on detached olive branches and two-year-old olive trees in the greenhouse. This is the first report of C. pruinosa causing olive branch and fruit dieback in Croatia.

Identification and Pathogenicity of Biscogniauxia and Sordaria Species Isolated from Olive Trees

“…Cytospora spp. has been identified as an olive pathogen in California [5], Croatia [6], Greece [7], Spain [8] and South Africa [9,10]. Similarly, species from the Botryosphaeriacea family, namely Diplodia spp., Dothiorella spp.…”

“…These fungi enter the tree through wounds, naturally occurring openings or pruning incisions [8]. The manifestations of trunk diseases in olive trees can exhibit variability but frequently encompass branch dieback, diminished fruit production and wilting [6,20]. Pycnidia and/or perithecia of certain fungi linked to olive dieback can be discovered embedded in the bark of the affected areas [11].…”