Foliar blight, leaf spot, and stem blackening diseases caused by Stemphylium beticola, Alternaria alternata, and Alternaria atra on dragon's head (Lallemantia iberica) in Iran

Dragon's head, Lallemantia iberica, is an oilseed crop adapted to be grown in cold-dry areas. In the growing season of 2022–23 a severe foliar blight, leaf spot, and stem blacking symptoms were observed in commercial fields in northern and northwestern Iran, leading to more than 50 % yield loss. Infected samples were collected and transferred to the laboratory. Following the isolation of fungal agents, five representative isolates were selected for further studies. Morphological studies, based on conidial shape, conidiation, and other mycological characteristics, were carried out on a pure culture established from a single spore. Furthermore, multigene phylogenetic analyses were performed using sequences of translation elongation factor 1-α (TEF1), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), RNA polymerase II second largest subunit (RPB2), and Internal Transcribed Spacer (ITS) rDNA genes for Alternaria isolates, along with calmodulin (cmdA) for the Stemphylium isolate. The morphological and molecular studies identified the fungal isolates as Alternaria atra, Alternaria alternata, and Stemphyliium beticola. Pathogenicity tests on the commercial cultivar ‘Sara’ indicated that all isolates were pathogenic to dragon's head, but they differed significantly in aggressiveness. To the best of our knowledge, this is the first report of the association of these fungal species with an important foliar disease on this crop in Iran and worldwide. •Stemphylium beticola, Alternaria alternata and A. atra are three fungal pathogens isolated from infected Lallemantia iberica sampled from commercial infested fields of Iran.•These three pathogens producing foliar blight, leaf spot and stem blacking are responsible to yield loss up to 50 % in infested fields.•There are significant differences between isolates belonged to these species in term of aggressiveness on the examined Dragon's head commercial cultivar.