The single most destructive fungal disease of azaleas is probably Phytophthora root rot caused by Phytophthora cinnamomi. It is a soil-inhabiting organism, and it attacks the small feeder roots. This disease is most prevalent in soils that remain wet for periods of time or have poor internal drainage. The pattern of disease attack is random plant death in the landscape. Control is available but not very effective in home plantings. Improving surface and internal soil drainage and purchasing disease-free plants are critical in preventing further spread.

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