Disentangling Co-Occurring Pathogens: Lack of Significant Interaction Between Agrobacterium tumefaciens and Ganoderma adspersum in Almond Orchards.

Abstract

While plant diseases often involve co-infections of multiple pathogens, there are few studies that focus on understanding plant host-multi-pathogen interactions. To understand the complexities of cross-taxa co-infections, we investigated the interactions between an almond tree, wood-decay pathogen, Ganoderma adspersum, and a bacterial pathogen, Agrobacterium tumefaciens. The high co-incidence of the fungal and bacterial pathogens in almond orchards suggests mutualistic effects in pathogenesis. However, co-inoculation assays revealed that the pathogens do not significantly interact directly with each other nor promote increased initial disease development. The rise of multi-pathogen diseases in almonds likely results from the adoption of management practices that have created a system capable of sustaining multiple pathogens.