Evaluation of some chemical and biological fungicides for controlling stem canker on apricot trees caused by Neoscytalidium dimidiatum

Neoscytalidium dimidiatum (Penz.) Crous & Slippers has caused considerable damage to apricot trees in Türkiye in recent years. This study, conducted in Malatya, Türkiye (2021–2022), evaluated ten chemical and two biological fungicides to control N. dimidiatum, a serious pathogen in apricot trees causing dieback, canker, and host death. Chemical fungicides were tested both in vitro and under field conditions. Biological fungicides were tested only under field conditions. In vitro tests revealed that the majority of chemical fungicides tested, with the exception of metalaxyl-m + acibenzolar-s-methyl (10.46%), efficiently suppressed N. dimidiatum mycelial growth. Regarding the inhibition of mycelial growth of N. dimidiatum, the most effective fungicides were classified as follows: Tebuconazole (100%), cyprodinil + fludioxonil (99.43%), azoxystrobin + difenoconazole (99.40%) and floupyram + tebuconazole (99.26%). Chemical fungicides that showed high efficacy under in vitro conditions also proved effective in field trials. In contrast to the chemical fungicides, the commercial Bacillus subtilis and Trichoderma harzianum Rifai KRL-AG2, tested exclusively in field studies, did not show significant efficacy against N. dimidiatum. This research provides the first field-based insights for managing N. dimidiatum in apricot saplings.