In vitro and in vivo activity of chemical fungicides and a biofungicide for the control of wood diseases caused by botryosphaeriales fungi in apple and pear

Abstract Dieback and canker disease caused by species of Botryosphaeriales affect the productivity of pome fruit orchards. In this study, we evaluated the efficacy of fungicides and biofungicide for controlling canker and dieback diseases in apple and pear using in vitro and field trials. Isolates of Diplodia seriata, D. mutila, and Dothiorella omnivora from apple, and of D. seriata and Aplosporella aquifolii from pear were used. Cercobin® (thiophanate-methyl), followed by Bellis® (pyraclostrobin + boscalid), and Nativo® (tebuconazole + trifloxystrobin) inhibited mycelial growth, conidial germination and pycnidia formation in vitro in all fungal isolates. T. harzianum produced mycelial growth inhibition and mycoparasitism in dual culture assays. Thiophanate-methyl and T. harzianum fully inhibited pycnidia production, while pyraclostrobin + boscalid and tebuconazole + trifloxystrobin were most effective against conidia germination. In the orchard assays, protective sprays of the fungicides on pruning wounds reduced incidence by up to 20%, while T. harzianum and tebuconazole + trifloxystrobin reduced the lesion severity up 37 and 41%, respectively. This study represents the first evaluation of fungicides and biofungicide effectiveness for the control of canker and dieback diseases of apples and pears in Argentina.