Groundbreaking research addresses innovative approaches to Douglas fir root diseases

Photo of a Douglas Fir root with laminated root rot fungus.
Close-up view of the fungus that causes laminated root rot (white stuff on root). Photo: Amy Ramsey-Kroll/DNR

Laminated root rot is becoming more of an issue in Washington State. Why? The disease affects many conifers, including Douglas fir, a vital resource for Washington’s economy and ecology.

A recently released report addresses new approaches to understanding root rot diseases, with a focus on laminated root rot Commissioner of Public Lands Peter Goldmark requested the study, which was conducted by the Washington State Academy of Sciences.

What is laminated root rot?
Laminated root rot is caused by caused by the fungus Phellinus sulphurascens and affects Douglas fir, western hemlock, and other conifers.

Why is this disease so troubling?
The fungus can persist more than 40 to 50 years in roots and stumps and spread from root to root. The fungus eats the living tree roots, causing trees to weaken and fall, endangering roads, homes, campgrounds, and people.

In managed forests, root diseases contribute to major losses in forest growth and have a tremendous impact on revenue from timber sales. If an infected site is harvested, then replanted with Douglas fir, the disease is likely to increase its presence in the stand, killing young trees, setting back forest regeneration, and reducing future productivity.

This study is important because revenue from harvested timber from DNR-managed trust lands funds public schools, universities, and other trust beneficiaries.

Study highlights
The study committee identified a number of opportunities to use existing and emerging tools in molecular genetics and genomics to better understand the dynamic ecological interactions that contribute to forest root diseases and open new approaches to its management. This research could quickly lead to innovative ways to reduce disease infection and tree mortality. Examples of new approaches include:

  • Developing tools to improve foresters’ ability to rapidly and accurately identify laminated root rot.
  • Conducting comprehensive genetic analyses of laminated root rot and close relatives from different host trees and on different continents can help our understanding of how this fungus and its host tree evolved together.
  • Identifying and characterizing at the molecular level how genetically based resistance in populations of Douglas fir could potentially aid plant breeding efforts to preserve or enhance specific tree qualities that reduce susceptibility.
  • Identifying the tree-defense and fungus-virulence genes that occur during specific stages in Douglas fir/laminated root rot host/pathogen interactions.
  • Identifying the microbial composition of the soil surrounding healthy and laminated root rot-infected Douglas fir roots and clarifying whether differences exist between nursery seedlings used for reforestation and naturally established seedlings.

Read the study: Opportunities for Addressing Laminated Root Rot Caused by Phellinus Sulphurascens in Washington’s Forests

News release announcing study.

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