In 2002 and 2003, studies in nurseries throughout California and Oregon tested for "Phytophthora ramorum". The symptoms of the disease were large necrotic spots with water soaked outside borders and rust colored centers. Symptomatic plants were collected, and DNA was extracted from the spots. After amplifying it with a PCR assay, GenBank matched the DNA to that of "Phytophthora ramorum" and "P. lateralis". In 2004, Rhododendron leaves with similar symptoms were studied and showed the host range of P. hibernalis as well (Blomquist et al. 2005).