Pathogenicity testing of lesser-known fungal trunk pathogens associated with wood decay of almond trees

Abstract

Cross infection of multiple hosts by fungal trunk pathogens has been reported to occur worldwide. It supports the hypothesis that infected hosts adjacent to vineyards may serve as sources of inoculum for these pathogens. Among the alternative hosts, different studies have shown that almond represents a rich catch-crop for many fungal trunk pathogens. The hyphomycetes Collophora hispanica, Phaeoacremonium (Pm.) amygdalinum, Pm. iranianum and Pleurostomophora richardsiae have recently been isolated from wood samples with internal necroses and brown to black vascular streaking of almond trees showing symptoms of decline in Spain, although their status as pathogens was so far unknown. We inoculated almond trees cv. Ferragnes with these fungal species in greenhouse experiments to determine their pathogenic potential. All of them infected, colonised and produced lesions statistically different from the control, Pl. richardsiae being the most aggressive. Therefore, Co. hispanica, Pm. amygdalinum, Pm. iranianum and Pl. richardsiae should be considered as trunk pathogens of almond trees.