Rhododendrons are members of the Ericaceae family and are frequently used shrubs that enhance any landscape. According to the University of Kentucky, College of Agriculture diseases in rhododendrons are usually the result of poor growing conditions. These shrubs grow best in locations that provide partial shade and protection from the late day sun and wind. Reducing stress from heat or drought reduces the likelihood of disease.
Nematodes - Rhododendrons are particularly susceptible to nematode infestation. Infested plants suffer damage as the leaves turn yellow and plants are stunted. Failure to respond to treatments such as fertiliser is common with nematode infestation. Rhododendrons gradually die from this condition, as there are no chemical treatments available to control nematode infestations on rhododendrons. Preventing nematode damage is best accomplished by providing good growing conditions, water and partial shade.
Botryosphaeria Dieback - According to the University of Kentucky, College of Agriculture, one of the most common rhododendron diseases is Botryosphaeria Dieback. This fungal disease often attacks plants within the first few years after transplanting. Symptoms associated with Botryosphaeria Dieback in rhododendron plants include the growth of dead branches among healthy branches and the leaves on dead branches may roll downward and turn brown. Infection often begins at pruning wounds or leaf scars. Reducing plant stress is important to preventing Botryosphaeria Dieback in rhododendrons. Shade the plants from hot afternoon sun and provide them with plenty of water. Removing dead branches helps prevent the spread of the disease.