MONITORING BLISTER RUST SPREAD AND ESTABLISHMENT IN THE
CENTRAL ROCKY MOUNTAINS: STAGE 2
Kelly Sullivan Burns and Brian Howell
USDA Forest Service, Rocky Mountain Region, Forest Health Management, Lakewood Service Center
INTRODUCTION
RESULTS
An Evaluation Monitoring project was initiated by J.L. Harris (USFS-R2FHM) and J.T. Hoffman (USFS-R4-FHP) in 2001 to monitor the
distribution and spread of white pine blister rust (WPBR) in the central
Rocky Mountains. Field crews discovered isolated outbreaks of white
pine blister rust (causal fungus Cronartium ribicola) in the Sangre de
Cristo and Wet Mountains of southern Colorado in 2003. Most infected
trees were limber pine (Pinus flexilis) although infected Rocky Mountain
(RM) bristlecone pines (P. aristata) were identified for the first time in
their native range within the Great Sand Dunes National Park and
Preserve (GRSA). In light of the new infestations a more in-depth
survey was initiated in southern Colorado in 2004.
• Incidence and intensity of WPBR on plots were inversely correlated with
elevation.
• There was no relationship between Ribes presence on plots and disease
incidence.
• Incidence of severe infections was significantly greater on trees smaller
than 6 inches DBH.
• No infected trees were observed above 10,076 feet.
Sangre de Cristo Mountains
• 26 long-term monitoring plots were established.
• The distribution of WPBR extends from Medano Pass to the Huerfano
River on the east side and North Arrastre Creek on the west side.
• WPBR intensity on plots was greatest (56%) on the west side of the
range within the GRSA along Mosca Creek.
• The disease has been present since 1993 based on maximum canker
length (Kearns 2005).
METHODS
•
•
•
•
•
OBJECTIVES
Survey locations were selected randomly. The occurrence of WPBR was not a selection
factor.
Methods were adapted from Smith and Hoffman (2000) and the Whitebark Pine
Ecosystem Foundation (Tomback et al. 2004).
Site data collected included: elevation, slope, aspect, stand structure, slope position,
species mix, regeneration, needle retention, and Ribes species present in the plot and
their density.
White pine variables included: species, DBH, height, health status, crown class, incidence
of cones, number of cankers and their characteristics, and other damages and severities.
A WPBR severity rating was assigned to infected trees based on the distance from the
bole to the nearest (most lethal) canker:
9MINOR = cankers > 24 in from bole
9MODERATE = cankers 6 - 24 in from bole
9SEVERE = cankers < 6 in from bole or on bole
Wet Mountains
• WPBR is scattered throughout the range extending from Holt Mountain to
just west of the town of Rye.
• No infected trees were observed on the western slopes of the range.
• WPBR intensity on plots was greatest west of Beulah (79%).
• The disease has been present since 1999.
Incidence on Bristlecone Pine
• 1 infected bristlecone pine was observed in all plots combined.
• Infected bristlecones were observed along Mosca Creek, GRSA only. No
infected bristlecone pines were observed in the Wet Mountains.
1) Delimit the current geographic extent and intensity of the
southern Colorado infestation.
2) Determine the incidence of the disease on RM bristlecone pine.
3) Establish long-term survey plots in the Sangre outbreak to
monitor distribution, rates of spread, intensification and
ecological impacts of the disease.
4) Create a GIS database of recent USFS (R2, 3, 4) and Colorado
State University survey locations that can be used to map the
current distribution in the central Rockies and locate areas for
future surveys and monitoring.
Plots were belt transects. Length and width varied to ensure
approximately 30 living white pines occurred in each plot.
White Pine Blister Rust Damage
57%
60%
Twig beetles were the most
common damaging agent
observed.
Over 90% of
plots had
white pine
regeneration.
Infected
regeneration
was observed
in 10% of all
plots.
ACKNOWLEDGEMENTS:
This project could not have been completed without the help of many others. Special thanks to Meg
Halford, Michele Laskowski, Russell Beam, Phyllis Bovin, Anna Schoettle, Bill Jacobi, Brian Geils, Jim
Worrall, Jim Blodgett, Jim Hoffman, John Guyon, Dave Conklin, Dan Ryerson, Mike Smith and Ed
Biery. Funding was provided by the USDA Forest Health Monitoring, Evaluation Monitoring Program.
Percent of Infected Trees
50%
40%
30%
20%
24%
19%
10%
Most infected
trees had
stem cankers
or cankers
within 6” of
the stem.
Minor
Moderate
Photo credit: Anna Schoettle
Infected RM bristlecone pines were
observed only within the GRSA.
0%
Severe
Damage Severity Class
Sangres
Total Plots
36
% with WPBR
50
Mean Intensity
(infested plots only)
14%
Wets
56
21
25%
Mean
Mean Elevation
Elevation (infested plots only)
10,137
9,731
9,572
8,690
Contact Information:
ksburns@fs.fed.us, behowell@fs.fed.us
A GIS database was created to display and query the nearly 1000
stands that have been surveyed in the central Rockies since 1997.
REFERENCES:
Kearns, H.S.J. 2005. White pine blister rust in the central Rocky Mountains: Modeling current
status and potential impacts (Ph.D. diss., Colorado State University, Fort Collins, CO). 243 p.
Smith, J.P. and Hoffman, J.T. 2000. Status of white pine blister rust in the Intermountain
West. Western North American Naturalist 60: 165-179.
Tomback, D.F., Keane, R.E., McCaughey, W.W. and C. Smith. 2004. Methods for surveying
and monitoring whitebark pine for blister rust infection and damage. Whitebark Pine Ecosystem
Foundation, Missoula, Montana. 28 p.
http://www.whitebarkfound.org/PDF_files/WPEF%20Blister%20rust%20survey%20methods%20(
2).pdf