Crown Gall Disease: A Growing Threat to Fruit Tree Health and Productivity (A Case Study from North Africa)

Abstract Crown gall disease is a widespread plant disease manifested by the development of tumors on several plant species. Stone fruit trees, grapevine and roses remain particularly susceptible to this disease. The causal agent of this disease are pathogenic agrobacteria of different genus species. They are responsible of serious economic losses in landscapes, nurseries and orchards. Although agrobacteria are common bacteria in soils, and may have beneficial attributes to plants, they become tumor-inducers once they gain the plasmid Ti, and can make soils unsuitable for susceptible cultures for decades. The dynamic and outbreak fluctuations of pathogenic agrobacteria are closely related to climate factors. Therefore, climate changes are thought to be responsible of the recent outbreak of this disease on vineyards in some North African countries. Although serious efforts have been deployed in searching for more sustainable management solutions, a systemic review of studies on crown gall in this region shows a lack of information regarding the current situation of the disease. Crown gall control is believed to be achievable only with exhaustive analyses of both pathogenic and non-pathogenic agrobacteria, as the Ti plasmid (responsible of the gall induction) is conjugally transmitted among all agrobacteria. Information © The Authors 2025