Several fungi cause Botryosphaeria canker and dieback. Giant sequoia is a common host of B. dothidea, which also infects alder, coast redwood, incense cedar, madrone, and many other woody species. Other Botryosphaeria (=Diplodia) spp. diseases include oak branch canker and dieback and Raywood ash canker and decline.
Identification
Killed branches and sometimes large limbs are scattered throughout the canopy. Branches dying or recently killed from B. dothidea are reddish brown and often exude drops of yellowish pitch, while branches with older infections are grayish brown and (on conifers) mostly bare of foliage. On madrone, dead, brownish leaves often remain attached to dead bark that is gray, reddish, or black, depending on how long ago it died.
There are many other common causes of cankers, including other species of canker fungi.
Life cycle
Botryosphaeria typically infects hosts that are drought stressed or grown away from their native habitat, especially at warmer locations. The fungi spread primarily in splashing water during rain. Infections may develop slowly for many months before symptoms become visible.
Solutions
No matter how good the cultural care provided, species such as giant sequoia are not adapted to heat and develop Botryosphaeria canker where hot weather prevails.
Grow species that are well adapted to local conditions and provide them with proper irrigation and other cultural care.
