In addition to ornamentals, cotton, grape, tobacco, and many vegetables are also susceptible to attack by A. tumefaciens. Initially, small, soft, green or white swellings appear on lower stems at the soil line or crown of the plant. Swellings or galls may also appear on roots and sometimes on the lower stems or trunks. As the galls continue to develop and enlarge, the surface layers may become brown, woody, and roughened. With old galls, the surface layers often decay and slough off.
Galls can be spherical or contorted into a variety of shapes.
Plants with galls usually become unthrifty and possibly stunted. Plant death may eventually occur. Persistence And Transmission. Agrobacterium tumefaciens is a soilborne bacterium that is often introduced into landscape beds on diseased plant material or infested soil. The bacterium enters through wounds on the roots or crowns of the plant.