A new disease complex, referred to as "sudden oak death", has killed thousands of coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and tanoak (Lithocarpus densiflorus) trees in California since 1995. Additional hosts in other plant families are still being discovered. The primary pathogen, Phytophthora ramorum, probably an introduction into North America, is now found from Big Sur to Mendocino Co. The primary symptom in infected oak trees is a characteristic "bleeding" of viscous sap. Bark beetles (Pseudopityophthorus pubipennis) and ambrosia beetles (Monarthrum scutellare and M. dentiger), normally associated with dead and severely weakened trees, are rarely observed in living trees. In trees with bleeding cankers caused by P. ramorum, these beetles colonize the bleeding areas of the trunks in unusually large numbers. Trees with multiple Phytophthora infections and extensive beetle colonization may live for two or more years. However, these trees are prone to accelerated structural failure rates. The attraction of beetles to infected trees is being monitored in trapping studies. The role of beetles in the loss of structural integrity in living trees will be explored. The possible involvement of these beetles as vectors of the pathogen will be discussed.
Species 1: Coleoptera Scolytidae Monarthrum scutellare
Species 2: Coleoptera Scolytidae Monarthrum dentiger
Species 3: Coleoptera Scolytidae Pseudopityophthorus pubipennis
Keywords: Phytophthora ramorum, sudden oak death
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA