Botryosphaeria canker disease is the most common cause of leaf roll and eventual dieback of individual rhododendron branches. Cankers on stems and branches are caused by species of the fungus Botryosphaeria and are often found on plants growing under stressful conditions. Not surprisingly then, this is one of the most common diseases occurring in the first couple of years after transplanting. Other stress factors include cold winter temperatures, summer heat and drought, and mineral element deficiency. Other fungi such as Phytophthora can cause shoot dieback, but Phytophthora dieback is not associated with plant stress. To manage Botryosphaeria dieback, reducing plant stress such as transplant shock is the most important control measure. Heat and cold stress are difficult to avoid, but drought stress can be alleviated with watering, and mineral element imbalance can be corrected. Promptly pruning out all of the dead and dying branches to below the cankered, discolored wood will help prevent the spread of the disease, as will avoiding all unnecessary wounds.

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