Blueberry is considered one of the most disease-free fruit crops in Kentucky. Many of the diseases that affect blueberry result in minor damage. However, the most common disease of blueberry, Phytophthora root rot, can cause severe dieback and often results in plant death. The causal agent of blueberry root rot is Phytophthora cinnamomi, a soilborne water mold that occurs world-wide and can infect a wide range of hosts, including woody ornamentals. Under optimal conditions, the pathogen proliferates, and disease symptoms occur.