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Portland, Ore. August 31, 2010. “My
job was to locate the previously marked study trees. . .and record
data on the activity
of treated blister rust cankers,” wrote Charles “Terry “ Shaw. “The
work took [me] in rickety four-wheel drive vehicles to remote locations
scattered across the white pine forests of northern Idaho.” Shaw,
now editor of a recently published special issue of Forest Pathology,
described how 44 years ago, he and other young forestry students
collected data about a destructive forest disease for senior scientists.
Today,
Shaw and his colleague, Dr. Brian Geils of the Rocky Mountain Research
Station are now the senior scientists. Together, they
have compiled a collection of 12 journal articles on the biology
and management of Cronartium ribicola, an introduced invasive pathogen
that causes white pine blister rust, a seriously damaging disease
of North American white pines.
The August 2010 journal issue provides
a synthesis of knowledge on C. ribicola, identifies policy and
management actions to mitigate
disease impacts, and reviews future issues facing white pine management
such as climate change and new pathogen introductions. Through
this comprehensive and scholarly review of the literature, Shaw,
Geils, and thirty-three contributing authors provide a scientific
basis for protecting and sustaining white pine ecosystems.
“
The rust pathogen has a very complicated life cycle,” explains
Shaw, “with
five different spore stages alternating between two different hosts.” The
disease produces stem cankers that can eventually girdle and kill susceptible
host pines; spores that can only infect Ribes (currants and gooseberries) are
produced on infected trees. The fungus intensifies on Ribes leaves and may
cause early defoliation; but more importantly wind-born spores spread the rust
back
to nearby white pines. Until the 1960s, managers exploited this requirement
in the rust’s life cycle to control the disease by poisoning or grubbing
out Ribes bushes from farms and forests. Although Ribes eradication reduced
losses
in some stands and provided needed employment during the Depression, the practice
was unreliable, expensive, and could be environmentally damaging. Continued
research discussed in the special issue has led to silvicultural and genetic
practices
that are used today and could be adapted for managing future populations of
white pines for their economic and ecological values.
The western white pine
is an evergreen tree capable of rapid growth to great
size with desirable wood properties. This pine and the similar sugar pine
were once important timber trees, but logging, other disturbances,
and loss of regeneration
led to a marked decline in supply.
The release of the publication compiled
by Shaw and Geils coincides with the centennial of the introduction
of the pathogen to Western North America
as
well as the Great Fire of 1910, often called the largest fire in American
history. This fire burned over 3 million forest acres in northern Idaho
and western
Montana
and killed 86 people. The area it burned was about the size of the state
of Connecticut and the forests were said to be so dense that a person had
to cut
a way through.
Also consumed in this fire were acres and acres of western white pine.
After the destruction, the white pine readily regenerated, along
with the Ribes
which set up a perfect condition for the newly introduced Cronartium ribicola
to
kill millions of young pines.
In higher elevations of the mountainous West
where white bark pine grows, white pine blister rust and bark
beetles have so devastated some populations
that
the Department of the Interior is now reviewing a petition to list the
species as
threatened or endangered. This special issue of Forest Pathology contains
considerable scientific information that may be of significant value
as the agency evaluates
the status of this tree species.
Shaw, Geils and their colleagues hope
this edition of Forest Pathology (volume 40, issue 3-4, 145-418,
August 2010) will inform and increase
discussion and solutions to managing and eventually controlling the
spread of this
disease
on white pines. To read the abstract and order a copy of the journal
please visit
http://onlinelibrary.wiley.com/doi/10.1111/efp.2010.40.issue-3-4/issuetoc.
_____________________________________________________________________
The PNW Research Station is headquartered in Portland, Oregon.
It has 11 laboratories and centers located in Alaska, Oregon, and
Washington and about 425 employees.
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