Pacific Northwest Research Station

Behavior, Chemistry, and Ecology of Forest Insects and Diseases Team

2008 Science Accomplishments

Compounds in heartwood may slow spread of sudden oak death

Wood chips from the heartwood of western redcedar appear to slow the spread of pathogen. Credit: Rick Kelsey

From the public land manager to the homeowner with an oak tree in the front yard, people are looking for ways to limit the spread of Phytophthora ramorum, the pathogen that causes sudden oak death.

To address this need, scientists tested the antimicrobial activity in extracts from the heartwood of seven conifers and identified their volatile constituents. They found that extracts from the heartwood of incense-cedar and western redcedar were the strongest inhibitors of pathogen growth.

A field trial in California showed that heartwood chips from western redcedar placed on the forest floor for 4 months under a host tree with symptoms of sudden oak death significantly limited the accumulation of P. ramorum DNA in the litter layer. Heartwood chips or shavings from conifers with strong antimicrobial activity toward this pathogen might be useful in slowing its spread as part of an integrated pest management program.

Also, scientists identified several individual chemicals in the heartwood extracts with potent antimicrobial activity that potentially may be used in products such as foliar sprays to increase resistance against P. ramorum.

Partners: Agricultural Research Service, USDA Forest Service Pacific Southwest Research Station, Oregon State University

To learn more, contact Rick Kelsey at rkelsey@fs.fed.us.

Tool: A field guide to predict delayed mortality of fire-damaged ponderosa pine

Description: This field guide for land managers can be used to determine the probability of mortality for an individual tree, or the proportion of trees projected to die within a stand. It is recommended for use in any stand throughout southeastern Oregon or northern California. In the absence of a more accurate validated model, the field guide can be used for ponderosa pine elsewhere in Oregon and Washington. It can be used for trees damaged by prescribed fire or wildfire and is applicable to trees ranging from 3 to 83 inches in diameter and of various ages.

Contact: Walt Thies at wthies@fs.fed.us

More information: Gen. Tech. Rep. PNW-GTR-769. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 16 p. http://www.fs.fed.us/pnw/pubs/pnw_gtr769.pdf