Susceptibility of fig cultivars to Diaporthe canker in Iran

Fig canker is a serious concern in the major fig-growing region of Iran, Fars Province. The disease reduces yield and the lifespan of fig trees, particularly the dominant commercial dried fig cultivar, Sabz. Four consecutive years of surveys (2019-2022) led to the identification of four distinct canker types (A-D) in infected fig orchards in southern Iran. Morphological identification and multiple gene phylogenetic analyses indicated that 218 (>66% of the total) isolates from infected fig cultivars belonged to Diaporthe cinerascens, all of which were recovered from Type A cankers, that is, trunk cankers with zonation. Based on scales developed by the principal component analysis (PCA) approach of pathogenicity characteristics, D. cinerascens isolates were clustered into three groups: low, moderate and highly aggressive. The susceptibility of 10 drought and/or salinity-tolerant fig cultivars to a highly aggressive D. cinerascens isolate was evaluated based on five pathogenicity characteristics. These cultivars were clustered into nonsusceptible (cultivar Matti), semisusceptible (the majority of the cultivars) and susceptible (cultivars Dehdez and Gilasi). The present study is the first attempt to assess the response of fig cultivars to the most significant and common pathogen causing fig canker, D. cinerascens, by phenotyping techniques.