The fungus Botryosphaeria can cause a branch dieback on horsechestnut, redbud, dogwood, beech, walnut, tulip poplar, sweetgum, crabapple, pine, oak, rhododendron, azalea, rose, willow, elm, yew, and many other woody ornamentals. Cankers girdle and kill twigs and branches. Small black fungal fruiting structures which contain fungal spores develop in the canker. Rough, sunken, dark brown to black areas form around wounds or natural openings in the bark. The wood and pith of the branch is blackened or turn dark brown.
Dead bark falls off the cankered area .
Leaves on affected branches wilt as affected branches die. Cankers enlarge along the branch more quickly than around its circumference. Botryosphaeria enters natural openings in the bark, such as lenticels or through pruning cuts and other wounds. Plants most susceptible to the disease are wounded plants that are under drought stress. The fungus remains dormant in the wood during the winter.