Symptoms A consistent suite of symptoms has been identified in tanoak , coast live oak , black oak and Shreve's oak . Although symptoms are similar in these species, their appearance, both chronologically and physically, varies somewhat among the four species. New growth may droop or turn yellow to brown.
Droop occurs on most or all of the crown, rather than in a localized area.
However, tanoak may not show the bleeding symptom at all. Bleeding has occasionally been observed at greater heights. The species of Phytophthora isolated from dying oaks does not match any of the 60 previously known Phytophthora species in the world. At this time it is unknown whether the fungus was recently introduced into California or if it is native and has only recently increased in importance as a tree- killer. The half-dome shaped fruiting bodies of the Hypoxylon thouarsianum fungus may also be present.