Cotoneaster Diseases

Disease	Symptoms	Pathogen/Cause	Management
Botryospaeria Canker	Leaves on affected branches wilt and die. Branches die back and become covered with dark brown to black pimple-like fungal fruiting structures. Wood under the bark is dark brown.	Botryosphaeria	Trees most susceptible are those under drought stress. Therefore, irrigate to prevent drought stress. Prune infected branches.
Fire Blight	Infected flowers are killed and often remain attached throughout the season. The ends of twigs and branches become brown or black and may curl over into a shepherd's crook shape. Dead leaves may remain attached to the tree. Cankers formed the previous season may ooze a cloudy liquid during wet spring weather. Branches will be killed as slightly sunken cankers enlarge into larger branches and even into the main trunk.	Erwinia amylovora	During dormancy when the weather is dry, prune infected branches, cutting at least 4 inches below the base of the canker. Disinfest pruning tools frequently. During the growing season, make pruning cuts at least 12 inches below the base of the canker. Fertilize carefully to avoid promoting excessive succulent growth. Remove root suckers and water sprouts while they are small. Remove nearby unwanted plants that are susceptible fire blight. Grow resistant types such as Cotoneaster anoenus, C. adpressus, C. canadensis, C. dammeri var. radicans, C. horizontalis, C. microphyllus, C. praecox, and C. zabelii.