During the summer it becomes active on plants severely affected by mite infestations. During propagation of cuttings, it becomes active after rooting, as new stem tissues develop. At this stage, spread of the disease can be controlled. Inoculum of Botryosphaeria is present in cankers of many trees and shrubs. It spreads as airborne spores early in the spring.
Chemical control is effective only if used on a preventative basis.
Sprays must be applied immediately after the damage has occurred. Plant types such as Rhododendron and Pieris do not recover once dieback symptoms have developed. Pruning of affected stems often does not prevent further decline. Control of Root Rots Cultural practices are very important for control of root rots. Part of this effect is due to the improved aeration and drainage properties as compared to peat-sand container media.