Results are poor growth of the affected area and eventual death of the cane. Stem canker is caused by several different parasitic fungi entering the stem through wounds or dying tissue. Brand canker appears as black sooty patches that develop during winter on climbing roses and those covered for winter protection. Cracking bark is common. The best control is pruning out the infected canes.
Brown canker appears as light brown lesions with deep purple margins.
This fungus will also attack foliage and buds on some cultivars. It is not common if a fungicide program is followed for control of other rose diseases. Stem canker appears as black spots, often at the point of mechanical damage. It is somewhat reddish and becomes brown, sunken and cracked with age. Cankers often appear on plants weakened due to black spot.