See:
Tanoak (Notholithocarpus densiflorus) - Sudden Oak Death
Rhododendron - Ramorum Leaf Blight and Shoot Dieback
Notes Mexican Orange is on the associated plants list where it has been found naturally infected with Phytophthora ramorum by culturing and/or detected using PCR. Generally, it causes leaf blight or dieback of twigs. Foliar inoculation tests, however, have shown Choisya ternata to be virtually immune.
References Defra. 2005. Non-tree host range and diagnosis of Phytophthora ramorum (sudden oak death) in support of pest risk assessment, management and policy. Project code PH0193S. Central Science Laboratory Research Project Final Report. file:///C:/Users/pscheidj/Downloads/p21006coll3_14514.pdf