New records of Bipolaris from Algeria causing leaf spots of corn including two new pathogens on the host, a challenge to corn silage production

Fungi, especially Bipolaris species, seem to be among the main causative agents of leaf diseases of corn in Algeria. This study aimed to investigate fungal species associated with these diseases in northern Algeria. For this purpose, corn leaves exhibiting spot and blight symptoms were collected from different fields across Algiers and Boumerdes regions. A total of 53 fungal isolates were recovered from the leaf samples and identified using morphological characterization and multi-locus phylogenetic analyses of the internal transcribed spacers 1 and 2 with intervening 5.8S nrDNA (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and translation elongation factor 1-α (TEF1) genes. All isolates were initially assigned to the Bipolaris genus based on conidial morphology and germination. Based on morphology and multi-locus phylogeny, the isolates were identified as B. cynodontis (15 isolates), B. salkadehensis (15 isolates), B. variabilis (11 isolates), and B. zeae (12 isolates). B. variabilis and B. zeae are closely related phylogenetically and displayed very similar morphological characteristics. Additionally, they were more aggressive and invasive in pathogenicity tests compared to B. cynodontis and B. salkadehensis which showed weak infections. This is the first documented occurrence of these four pathogens in Algeria and the first record of B. salkadehensis and B. variabilis on corn worldwide, providing useful information for disease diagnosis, prevention and control.