Site Visit by WSU Plant Pathologists Marianne Elliott and Jenny Glass

Tuesday November 10th, Dr. Marianne Elliott and Jenny Glass (Diagnostic Plant Pathologist) braved the traffic and drove up to Seward Park from the WSU Plant and Insect Diagnostic Laboratory in Puyallup.

Accompanied by undergraduate students Tristan O'Mara, Kramer Canup and me, Marianne and Jenny spent a couple of hours inspecting the extended die-off site, and collecting soil and leaf samples from affected sites and a mostly healthy region (Kramer and Tristan's 5x5m "Plot 1").

Jenny describes her self as a lab generalist (a most expert generalist, it seems to me).   Marianne is a research plant pathologist who, among other things, has coordinated (and is celebrated for) Washington's statewide response to Sudden Oak Death.  She is active in phytophthora research.  Though previous tests for Phytophthora came up negative (Jenny in 2014, Olaf Ribeiro in spring 2015) Marianne suggests that a closer and more sustained examination is worthwhile.

The site visit resulted in what is, at present, a very tentatively held hypothesis.  Marianne noticed small and mostly dead cedar seedlings, about 12 inches tall, each marked with a red-on-white plastic tag, in and around ground zero.   We found several of these up above the north-facing ground zero slope, the flat area where Catherine Alexander first noticed signs of distress and die-off.

Lisa Cieko learned from fellow Parks plant ecologist, Michael Yadrick, that these tagged cedar seedings were among 10,520 bareroot cedars Parks contractors had planted throughout the forest in February of 2011.  Lisa adds: one article that I found did says that this could be an issue -

      Root Rot of Western Swordfern Caused by Phytophthora cinnamomi in California.

The abstract mentions that the "pathogen was inadvertently brought to the site via rhododendron nursery stock".    

Thus we have a conjecture, a  hypothesis,  and the good fortune to also have experts both skilled and experienced to test it out.   Their lab methods may also reveal other candidates, may suggest other hypotheses.   We are very grateful to Marianne and Jenny!