Plants affected by root rot show an inward curling of the leaves. Drought alone, however, causes the same top symptoms. With root rot, a single branch near the soil surface may develop curled leaves, then die and drop its leaves. This branch dieback occurs when the root rot fungus is splashed up onto a leaf, infecting the leaf and the branch. Root rot of rhododendron is often symptomless in the landscape until stress from drought or flooding brings on disease.
Fertilizers are also important in predisposing the plants to disease.
High amounts of nitrogen fertilizer are the most important factor in bringing about the root rot disease in the urban landscape. It is particularly important to not add high nitrogen rates at transplanting. Fungicides for controlling root rots are available for use as soil drenches. Visuals associated with this text. This information is for educational purposes only.