EPPO Global Database

EPPO Reporting Service no. 05 - 2007 Num. article: 2007/096

Phytophthora foliorum a new species causing leaf blight of azalea

During surveys carried out for Phytophthora ramorum (EPPO Alert List) on nursery plants in California and Tennessee (US), a new species of Phytophthora was found on evergreen hybrid azaleas. This new species was described and called Phytophthora foliorum sp. nov. P. foliorum is morphologically distinct from P. ramorum, P. lateralis and P. hibernalis. However, it gave false-positive response when using the ITS-based diagnostic PCR primers designed to screen plant material for the presence of P. ramorum. So far, no significant azalea mortality attributed to P. foliorum has been observed, and this pathogen has only been found causing leaf spot symptoms on azalea. Further studies are needed to determine its origin, host range, potential impact, and potential establishment in natural ecosystems.


Donahoo R, Blomquist CL, Thomas SL, Moulton JK, Cooke DEL, Lamour KH (2006) Phytophthora foliorum sp. nov., a new species causing leaf blight of azalea. Mycological Research 110(11), 1309-1322.