Crown gall is a cancerous disease of many dicotyledonous plants that is caused by five main groups of soil and plant-inhabiting, ubiquitous, pathogenic agrobacteria: Agrobacterium tumefaciens (biovar1), Rhizobium rhizogenes (formerly Agrobacterium radiobacter and A. rhizogenes)(biovar2), A. vitis (biovar3), R. rubi (formerly A. rubi) and A. larrymoorei. These bacteria are present in most agricultural soils and cause disease that affect plants in nurseries, landscapes, vineyards and orchards worldwide.
