Sooty bark disease (squirrel scratches)
Emerging Concerns


Emerging Plant Health Issues of Concern

Introduction

Emerging issues

There are several plant health issues emerging as major concerns in the Pacific Northwest. A few concerns are highlighted below, but we will continue to update this section as new threats to plant health are detected.

More Research is needed

More research is needed because the factors driving these declines are not well understood. For example, changes in the environment and the onset of more frequent, longer and hotter droughts in some areas of the Pacific Northwest will affect the way plants and parasites interact.

It is often difficult to pinpoint the most important factors leading to the decline of species because it is often a complex interaction between organisms and the environment. Changes in the host plant, environment, pest or pathogen, or a combination of changes, can lead to the emergence of novel disease epidemics or pest outbreaks (see Disease Triangle). This complexity is further demonstrated by Manion’s Disease Decline Spiral, highlighting the numerous factors that can interact to drive tree mortality.

Invasive Species and Early Detection

The introduction of exotic organisms into our ecosystems can also drive irreversible change. Many novel disease epidemics and pest outbreaks have arisen from introductions of ‘alien’ or exotic species originating from other areas of the planet. It is therefore possible that the emerging plant health issues highlighted below are consequences of the introduction of an invasive plant pathogen or pest, but more research is needed.

the word "disease" inside a triangle. at the points of the triangle are the words: host, environment, pathogen
a spiral showing the contributing, inciting, and predisposing factors of disease decline of trees
Disease decline spiral from: Manion, P.D. 1991. Tree disease concepts. Second edition. Prentice-Hall, Inc., Englewood Cliffs, New Jersey

Briefs

Bronze Birch Borer
Agrilus anxius
Photo by John .A. Davidson
Bronze Birch Borer
Agrilus anxius
Photo by John .A. Davidson

Bronze Birch Borer

Emerald Ash Borer
Agrilus planipennis
Photo by Debbie Miller
Emerald Ash Borer
Agrilus planipennis
Photo by Debbie Miller

Emerald Ash Borer

Japanese cedar longhorn beetle
Callidiellum rufipenne
photo by Connecticut Agricultural Experiment Station
Japanese cedar longhorn beetle
Callidiellum rufipenne
photo by Connecticut Agricultural Experiment Station

Japanese Cedar Longhorned Beetle

Mediterranean Oak Borer
Xyleborus monographus
Photo by University of California Agriculture and Natural Resources
Mediterranean Oak Borer
Xyleborus monographus
Photo by University of California Agriculture and Natural Resources

Mediterranean Oak Borer

Spotted Lanternfly 
Lycorma delicatula 
photo by Lawrence Barringer, Pennsylvania Department of Agriculture
Spotted Lanternfly
Lycorma delicatula
photo by Lawrence Barringer, Pennsylvania Department of Agriculture

Spotted Lanternfly

Sudden Oak Death
Sudden Oak Death
Caused by Phytophthora ramorum
photo by WSU Urban Forest Health Lab

Sudden Oak Death

Row of dead Western Redcedars experiencing dieback
Western Redcedar Dieback
photo by WSU Urban Forest Health Lab

Western Redcedar Dieback

Western Sword Fern (Dead Stump)
Polystichum munitum
 Photo by WSU Tree Health Labs
Western Sword Fern (Dead Stump)
Polystichum munitum
Photo by WSU Tree Health Lab

Western Sword Fern Dieback