Gall plant disease, or crown gall, is a detrimental plant disease that can be found around the world. The disease infects trees and plants, alike and is known to infect more than 140 genera. Although unhealthy plants and trees are most vulnerable to crown gall, all plants are susceptible to this disease. Severe crown gall infections generally result in the death of the plant or tree.
Crown gall is a bacterial disease that infects the vascular system and DNA of the plant. Crown gall is a fairly weak disease that can only infect the plant through its open wounds and cracks. Once it enters the system, however, the disease takes on a much more aggressive approach. The Iowa State University Department of Plant Pathology explains that this causal bacterium mutates the infected plant's DNA by fusing its own DNA into its system.
Crown gall infections restrict the vascular systems of infected plants and trees. The infected vascular system becomes unable to transport water and nutrients throughout the system. As a result, infected trees and plants experience dieback of twig and branches, as well as growth stunt and wilt. Infected plants and trees will also develop small growths on the trunk, stems, crown and roots. Initially, these growths will appear as spongy and flesh-colored but will harden, darken and enlarge with age.
Once a plant or tree is infected with crown gall, it cannot be eliminated. However, gall infections can be controlled. The infected tree or plant must maintain vigorous growth in order to counteract this disease. Infected areas and galls must be pruned from the area. The pruning should be completed with sharp, sterile pruning shears that are sterilized between each cut. Severely infected plants and trees must be removed from the area and destroyed to prevent further outbreak in the area. The roots and stumps must also be removed.
Crown gall can thrive in the soil for years after infection without a host. Therefore, it is important to plant only resistant plants in the area. Seedling and bare-root plants should be treated with a bactericide prior to planting to reduce the potential of infection. Garden equipment, planting containers and shears must be sterilized and fumigated to prevent cross contamination. Trees and plants should also be protected from wounds and injury that can be caused by insects, gardening equipment and winter injury.
Certain best practices will also help to reduce the potential of crown gall infections. These practices include planting trees and plants when the soil temperature rests below 50 degrees F, keeping graft lines above soil level and always planting in clean soil. Proper fertilizing and irrigating will also reduce the potential of crown gall infections. Gardeners should avoid fertilizing during the late growing season to allow the plant or tree ample time to harden before the onset of the winter months. This practice will reduce the potential of winter injury, such as cracking and breakage.