Study on the Susceptibility of Some Almond (<em>Prunus dulcis</em>) Cultivars to the Pathogen <em>Diaporthe amygdali</em>

Diaporthe amygdali (anamorph Phomopsis amygdali) is a phytopathogenic fungus of considerable agronomic importance, responsible for branch canker in almond (Prunus dulcis) and peach (Prunus persica L.) trees, representing a major phytosanitary threat to almond cultivation in Europe—particularly in Mediterranean regions—where almond has become one of the most dynamic crops, with cultivated areas expanding rapidly as a result of new varietal introductions and improved agronomic practices. The objectives of this study were to: (i) isolate and identify fungal pathogens from infected almond samples collected in France through multilocus phylogenetic analyses (ITS, tef1-α, act, his3, tub2, cal genes) combined with morphological characterization; (ii) evaluate the susceptibility of 18 almond genotypes, using ‘Ferragnès’ and ‘Texas’ as reference standards for susceptibility and tolerance, respectively; and (iii) compare three field inoculation methods. All isolates were identified as D. amygdali. The varietal screening revealed notable resistance in cultivars ‘Ferrastar’, ‘R1877’, ‘R1413’, and ‘R1542’, whereas ‘Tuono’, ‘Guara’, ‘Ferragnès’, and ‘R1568’ were classified as susceptible. Among the inoculation techniques tested, the mycelial plug method proved to be the most consistent and reliable. The results confirm the presence of resistant genotypes, wich are useful for genetic improvement programs aimed at enancing resistance to related canker pathogens.