Susceptibility of fig cultivars to three fungal pathogens associated with Botryosphaeria canker

Abstract

Botryosphaeria canker poses a significant threat to the health and productivity of various woody plants, including edible fig trees, worldwide. This study aimed to evaluate the susceptibility of different fig cultivars to three prominent species of the Botryosphaeriaceae family: Botryosphaeria dothidea, Neofusicoccum parvum, and Neoscytalidium dimidiatum. These well-known canker-causing pathogens were isolated from infected fig trees in northern and western Iran and identified via morphological observations and molecular tools. This is the first global report of B. dothidea as a canker-associated pathogen on fig trees and the first report of N. parvum causing canker disease on fig in Iran. We assessed the susceptibility of 11 drought and/or salinity-tolerant fig cultivars to these pathogens using artificial inoculation of fig saplings. The assessment was based on six pathogenicity characteristics: external and internal lengths and widths of wood discoloration, number of pycnidia (whenever present), and latent period. The external length of wood discoloration was the principal contributor to the first dimension of principal component analysis (PCA), which accounted for 66.6 % of the total variance observed. This result was consistent with the outcome of the analysis of variance (ANOVA) conducted on this variable. Based on their clustering pattern in the PCA graph, as well as their ranking in induced lesion length from Tukey's multiple range comparison, fig cultivars could be classified into susceptible, semi-susceptible, and less susceptible groups. Ficus carica cv. 'Matti' exhibited the least length of wood discoloration and the most extended latent period when inoculated with the three Botryosphaeriaceae species. Among the pathogens, N. parvum was identified as the most aggressive, caused canker and dieback in inoculated fig saplings. The cultivars 'Siah', 'Sabz', 'Gilasi', and 'Dehdez' were susceptible to all three species within the Botryosphaeriaceae family. These findings enhance our understanding of Botryosphaeria fig canker and provides insights for future disease management efforts.