Olive Twig and Branch Dieback in California Caused by Cytospora oleicola and the Newly Described Species Cytospora olivarum sp. nov

• Published in: Plant disease p. PDIS09191979RE
• Main Authors: Úrbez-Torres, José Ramón, Lawrence, Daniel P, Hand, Francesca Peduto, Trouillas, Florent P
• Format: Journal Article
• Language: English
• Published: United States 01.07.2020
• Subjects: fungi; olive; pathogen detection; fruit; phylogenetics; dieback; etiology
• ISSN: 0191-2917
• DOI: 10.1094/pdis-09-19-1979-re

Field surveys conducted throughout California olive-growing regions in 2008 and 2009 resulted in a collection of 101 -like isolates from olive twig and branch dieback symptoms. isolates were isolated from multiple cvs. in different olive orchards in Fresno, Madera, Merced, Napa, Riverside, Santa Barbara, Sonoma, Tulare, and Ventura counties. Taxonomic studies of macro- and microscopic structures along with multigene phylogenetic analyses of the internal transcribed spacer region, including the 5.8S rDNA (ITS1-5.8S-ITS2), and fragments of the translation elongation factor 1-α, beta-tubulin, and actin genes identified two species, and sp. nov. Pathogenicity studies conducted in mature olive trees cvs. Manzanillo and Sevillano showed both species to be pathogenic and able to cause vascular necrosis and cankers in olive branches. This study adds to the current knowledge on the etiology of olive twig and branch dieback and provides new important information for the development of effective control strategies against canker diseases affecting olive in California.