Symptoms associated with inoculation of stems on living Douglas-fir and Grand Fir Trees with Phytophthora ramorum

Abstract

To obtain a better understanding of the potential risk of infection and colonization of living Douglas-fir (Pseudotsuga menziesii) and grand fir (Abies grandis) stems, the stems on over 150 trees of each species were inoculated at a Christmas tree farm near Los Gatos, California. This study had the following objectives: 1) Determine if inoculation timing affects the infection of living Douglas-fir and grand fir stems, 2) Characterize symptom development associated with inoculated stems, and 3) Determine what stem tissues were colonized by P. ramorum. Tanoak (Lithocarpus densiflorus) is highly susceptible to sudden oak death caused by Phytophthora ramorum. Symptoms include dying crowns, bleeding cankers, and, eventually, death of infected trees. The cause of mortality is not well understood, but we showed previously that naturally infected mature trees have reduced sap flow and reduced hydraulic conductivity. One possible mechanism for this is the presence of tyloses in xylem vessels formed in response to P. ramorum infection.

Parent Publication

• Proceedings of the Sudden Oak Death Fourth Science Symposium

Citation

Chastagner, Gary; Riley, Kathy; Coats, Katie; Elliott, Marianne; DeBauw, Annie; Dart,Norm. 2010.Symptoms associated with inoculation of stems on living Douglas-fir and Grand Fir Trees with Phytophthora ramorum. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M.  2010. Proceedings of the Sudden Oak Death Fourth Science Symposium. Gen. Tech. Rep. PSW-GTR-229. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 85-86