Back to “Basic Facts” questions How does P. ramorum impact plants?
Symptoms vary by plant species and often resemble symptoms caused by other species of Phytophthora. Laboratory tests are required to make a diagnosis. For most host species, the symptoms range from leaf spots to twig lesions. Some plant species suffer a die-back of stems or branches. A few species of plants can be killed by the fungus, including tanbark oaks and some live oaks. It is generally confined to attacking above-ground parts of plants, and is rarely found in soil or associated with roots. Thus, it is considered an aerial Phytophthora (as opposed to being a root-rotting form of Phytophthora.) It can persist either as an active, vegetative infection, or as a dormant spore. On some plants, including camellia, the fungus generally causes few symptoms, and it reproduces at a very low level. This combination of factors makes it difficult to detect on camellia and has thus set the unfortunate conditions that allowed the shipment of infected camellia plants to nurseries across the U.S
