Crown Gall is a disease that effects roses. It causes a large corky growth, that can grow to several inches in diameter. You will see it at the base of the plant, on the stems, and on roots.
The cause of Crown Gall is a soil-inhibiting bacterium ( Agrobacterium tumefaciens) This bacteria will effect not only roses, but ornamental plants, and fruit trees as well.
The bacterial causing this rose disease is usually brought to the garden initially on stems or roots of an infected plant that spread with soil, and contaminated pruning tools. (Always dip your pruning tools in bleach water, to disinfect them)
This rose disease (bacteria) will enter the plants in a wound in the stem or roots. Once inside the plant, they produce a compound that stimulates rapid cell growth in the plant, that causes the formation of the Gall.
Although this rose plant disease (Gall) does not usually kill the plant, it does disrupt the flow of nutrients and water from the stems and roots, which will weaken and stunt the top of the plant.
If the plant has many galls, it will appear weak: leaves will turn yellow, and growth is slowed. Branches or the entire plant may die back. Sometimes pests and diseases such as this has little effect on the bush, and removing the Gall is all that is necessary.
This plant disease, appear rounded, with rough irregular surfaces, and may be dark colored and cracked. They look like an ugly cracked growth.
Gall diseases of rose plants cannot be eliminated from a plant. The infected plant can live for many years. You can make it look better by pruning out any destroying any gall stems.(be sure to disinfect your pruning shears after each cut by dipping in a solution of rubbing alcohol or bleach water.)
The bacterium will remain in the soil for up to three years, so if you decide to replace the infected plant, select a new one that is resistant to this specific disease.
Note: I had this on one of my climbing roses, so I cut out the infected part. This rose continues to grow and produce beautiful roses for me (three years later)......So if you really love the rose, before trying any treatment for diseases such as Gall, cut it out, and see what happens.