Identification and Pathogenicity of Fungal Species Associated with Canker Diseases of Pistachio in California

• Published in: Plant disease p. PDIS10181717RE
• Main Authors: Nouri, Mohamed T, Lawrence, Daniel P, Holland, Leslie A, Doll, Dave A, Kallsen, Craig E, Culumber, Catherine M, Trouillas, Florent P
• Format: Journal Article
• Language: English
• Published: United States 01.09.2019
• Subjects: phylogeny; fungal pathogens
• ISSN: 0191-2917
• DOI: 10.1094/PDIS-10-18-1717-RE

A survey was conducted during 2015 and 2016 in pistachio orchards throughout the San Joaquin Valley of California to investigate the occurrence of canker diseases and identify the pathogens involved. Cankers and dieback symptoms were observed mainly in orchards aged >15 years. Symptoms of canker diseases included brown to dark brown discoloration of vascular tissues, wood necrosis, and branch dieback. In total, 58 fungal isolates were obtained from cankers and identified based on multilocus phylogenetic analyses (internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, β-tubulin, calmodulin, actin 1, and translation elongation factor 1α) representing 11 fungal species: , , , , , , , , , , and . Pathogenicity tests conducted in the main pistachio cultivars Kerman, Golden Hills, and Lost Hills using the mycelium-plug method indicated that all fungal species were pathogenic to . All species tested caused cankers in pistachio branches, although virulence among species varied from high to moderate. Overall, and spp. were the most widespread and virulent species associated with canker diseases of pistachio in California.