Characterization and pathogenicity of Cylindrocarpon-like asexual morphs associated with black foot disease in Algerian grapevine nurseries, with the description of Pleiocarpon algeriense sp. nov.

Several Botryosphaeriaceae species are known to occur worldwide, causing dieback, canker and fruit rot on various hosts. Surveys conducted in ten commercial citrus orchards in the northern region of Algeria revealed five species of Botryosphaeriaceae belonging to three genera associated with diseased trees. Morphological and cultural characteristics as well as phylogenetic analyses of the internal transcribed spacer (ITS) region and the translation elongation factor 1-alpha (tef1-α) identified Diplodia mutila, Diplodia seriata, Dothiorella viticola, Lasiodiplodia mediterranea and a novel species which is here described as Lasiodiplodia mithidjana sp. nov.. Of these, L. mithidjana (14.1% of the samples) and L. mediterranea (13% of the samples) were the most widespread and abundant species. Pathogenicity tests revealed that L. mediterranea and D. seriata were the most aggressive species on citrus shoots. This study highlights the importance of Botryosphaeriaceae species as agents of canker and dieback of citrus trees in Algeria.

A field survey conducted on asymptomatic grapevine propagation material from nurseries and symptomatic young grapevines throughout different regions of Algeria yielded a collection of 70 Phaeoacremonium-like isolates and three Cadophora-like isolates. Based on morphology and DNA sequence data of β-tubulin (tub2) and actin (act), five Phaeoacremonium species were identified including Phaeoacremonium minimum (22 isolates), P. venezuelense (19 isolates), P. parasiticum (17 isolates), P. australiense (8 isolates) and P. iranianum (4 isolates). The latter two species (P. australiense and P. iranianum) were reported for the first time in Algeria. Multi-locus phylogenetic analyses (ITS, tub2, tef1) and morphological features, allowed the description of the three isolates belonging to the genus Cadophora (WAMC34, WAMC117 and WAMC118) as a novel species, named Cadophora sabaouae sp. nov. Pathogenicity tests were conducted on grapevine cuttings cv. Cardinal. All the identified species were pathogenic on grapevine cuttings.