ARS | Publication request: The sporicidal activity of Chamaecyparis nootkatensis heartwood and constituents toward Phytophthora ramorum in culture

Submitted to: Pacifichem Symposium
Publication Type: Abstract
Publication Acceptance Date: June 30, 2005
Publication Date: December 15, 2005
Citation: Manter, D.K., Kelsey, R.G., Karchesy, J.J. 2005. The sporicidal activity of Chamaecyparis nootkatensis heartwood and constituents. toward Phytophthora ramorum in culture . Pacifichem Symposium.

Technical Abstract: Many plants protect themselves against attacks from insects or disease by producing compounds that function as a chemical defense. The purpose of this project was to determine whether defensive chemicals produced by non-host plants of Phytophthora ramorum can limit the growth, sporulation, or spore viability of this fungus. Laboratory bioassays show that heartwood from Chamaecyparis nootkatensis (yellow-cedar tree), its steam distilled essential oil, and individual compounds, are strong inhibitors of P. ramorum zoospore germination, sporangia germination, and hyphal growth. Nootkatin and carvacrol are the two most active compounds. Nootkatin instantaneously destroys the membrane surrounding zoospores and sporangia, but not the hyphae. Hyphal growth will resume if the compounds are removed. Yellow-cedar heartwood is abundant and can be read ily processed into shavings or sawdust, which with further research might be useful for reducing spore dispersal in areas infected with sudden oak death. It could be particularly helpful in treating areas where there are high levels of human activity, such as trails and parking lots of parks, or plant nurseries.