Severe infections cause defoliation. Coniothyrium canker is not a common problem in this area. However, it can be found in greenhouses. Occurrences were reported on outdoor roses in the spring of 1991. The fungal cankers eventually can girdle the plant.
Crown gall is caused by a bacterium that survives in the soil.
The pathogen enters the crown or roots via wounds made by mechanical damage or insect feeding. The tissue eventually girdles the rose and kills the plant. Destroy infected plants. The bacterium can survive in galls and plant residue in the soil for many years without a rose host. Do not plant roses in infested soil for at least five years.