|PSCHEIDT, JAY - OREGON STATE UNIVERSITY|
|OCAMB, CINDY - OREGON STATE UNIVERSITY|
|SACHER, GABRIEL - OREGON STATE UNIVERSITY|
|MESTAS, ANGELA - OREGON STATE UNIVERSITY|
Submitted to: Pacific Northwest Plant Disease Control Handbook
Publication Type: Other
Publication Acceptance Date: 12/30/2018
Publication Date: 1/1/2019
Citation: Pscheidt, J.W., Ocamb, C., Weiland, G.E., Scagel, C.F., Sacher, G., Mestas, A. 2019. Rhododendron-Phytophthora root rot. Pages 4R-28 to 4R-30 in Pacific Northwest Plant Disease Control Handbook. Oregon State University, Corvallis, OR. https://pnwhandbooks.org/node/3437.
Technical Abstract: Phytophthora root rot is a serious disease of both field and container rhododendron in the Pacific Northwest (PNW). The disease is caused by several species of Phytophthora, including the two most common species, P. cinnamomi and P. plurivora. Rhododendrons with Phytophthora root rot show symptoms of nutrient deficiency, wilting, and plant death. Cultural management includes reducing water logging and avoiding overfertilization. Resistant cultivars and species are available, though most have only been tested for resistance against P. cinnamomi. Many fungicides are also available that help control this disease.