Paramicrosphaeropsis eriobotryae as an emerging canker pathogen in pomegranate trees and the susceptibility of various cultivars

The pomegranate (Punica granatum L.) is highly valued for its significant health benefits, adaptability, cold resistance, and ability to thrive in low-fertility soils. Iran, a major producer, contributes nearly one-fifth of global pomegranate production, with Fars Province being the leading region. Recently, there has been a notable increase in pomegranate diseases, including decline, dieback, and canker. This investigation aimed to identify the fungal pathogens responsible for these diseases in Fars Province. Morphological and molecular analyses identified several fungal isolates belonging to Paramicrosphaeropsis eriobotryae, an emerging canker-associated ascomycete pathogen. The most aggressive isolate was identified through inoculation on detached branches of the 'Rabab-e-Neyriz' cultivar and subsequently used in pathogenicity assessments on five commercially important cultivars. The 'Malas-e-Saveh' and 'Wonderful' cultivars exhibited higher susceptibility, while 'Malas-e-Danesiyah-e-Esfahani' cultivar demonstrated relative resistance. Cross-pathogenicity assessments with isolates from pomegranate and other natural hosts, including fig, loquat, almond, and olive indicated diverse levels of host susceptibility and isolate aggressiveness. This study represents the first global report of P. eriobotryae causing branch canker and dieback on pomegranate trees.