Field Results of White Pine Blister
Rust Resistance in Sugar Pine and
Western White Pine Seedlings
Andrew D. Bower and Richard A. Sniezko
USDA Forest Service, Dorena Genetic Resource Center.
Field Results of White Pine Blister Rust Resistance in
Sugar Pine and Western White Pine Seedlings
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Background
Introduction
Objectives
Materials and Methods
Results
Discussion
Conclusions
Background
• White pine blister rust (Cronartium ribicola) (WPBR)
introduced to western N. America in 1910.
• WPBR affects western white pine (WWP)(Pinus
monticola), sugar pine (SP)(P. lambertiana) and other 5
needle pines.
• Alternate hosts are Ribes spp.
• Produces a diamond-shape canker that eventually can
girdle the stem, killing the tree.
• Low level of naturally occurring resistance.
• Major Gene Resistance and virulent strains of rust.
Introduction
• USDA Forest Service has been screening WWP and SP
for WPBR resistance since the 1950’s.
• Progeny of over 10,000 phenotypic selections have been
tested at the Dorena Genetic Resource Center (DGRC).
• <5% of these selections have >30% canker-free progeny,
and 95% of the seedlings develop lesions and die within
the 5-year evaluation period.
Objectives
• Investigation of field performance of progeny of
individuals selected in short-term screening.
• Field validation of resistance mechanisms
observed in artificial screening.
• Examination of the gains from WPBR resistance
screening and breeding.
Materials and Methods
• Established in Spring 1996 at Happy Camp,
California, with 1-0 container stock.
• 12 SP and 13 WWP families of varying resistance
levels.
• 12 blocks.
• Randomized complete-block design.
• 4 tree row-plots, each family represented once in
each block.
Measurements
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Height
Number of cankers on bole
Type and number of infections
Damage
Tree vigor
Stem Infection Types
• Normal (N) – active stem infection.
• Bark Reaction (BR) – canker inactive or “corked
out”.
• Partial Bark Reaction (PBR) – bark reaction with
some area of canker still alive.
• Blight (BL) – inactive canker on a branch that
was killed.
Analysis
• ANOVA used to test for differences between species and
among families within a species.
– Infection % (using rep means)
– Height (using individuals)
– # infections per tree (using individuals)
• X2 test of independence to determine presence of an
association between species and stem infection type.
Results
Results of analysis comparing species published as part of the
proceedings of the “Ribes, Pines, and White Pine Blister Rust
Conference” in Corvallis, Oregon. September 8-10, 1999.
HortTechnology 10(3):519-522
Survival and Growth
# Planted
# Surviving
% Survival
Height
SP
WWP
560
555
99.1%
34.8” (88.5cm)
616
607
98.5%
29.8” (75.6cm)
Infection Percent
SP
WWP
% of living trees infected
70.2%
34.3%
% with only 1 canker
27.5%
21.8%
% with >1 canker
42.7%
12.5%
Infection
SP
WWP
Total # of cankers
953
356
Total # of infected trees
393
211
Mean # Infections/tree
(infected trees only)
Range
2.42
1.69
0-17
0-9
Species Difference Results
P-value
Source
% Infection
Height
# Cankers
Block
0.0068**
0.0829*
0.1433
Species
0.0001**
0.0005**
0.0014**
-
0.0326**
0.2697
BxS
* Significant and a = 0.1
** Significant and a = 0.05
Family Analysis Results
P-value
Source
% Infection
Height
# Cankers
Block
0.0068**
0.0063**
0.0975*
Species
0.0001**
0.0019**
0.0001**
0.8444
0.2815
0.0893*
0.0001**
0.0001**
0.1714
-
0.0001**
0.0001**
BxS
Family(S)
B x F(S)
Observed and expected # of stem infections
Sugar Pine
Western White Pine
Obs.
Exp.
Obs.
Exp. Total
Normal
PBR
BR
BL
Total
256 (26.9%)
267
111
(31.2%)
100
367
134 (14.1%)
148
69
(19.4%)
55
203
394 (41.3%)
370
114
(32.0%)
138
508
169 (17.7%)
168
62
(17.4%)
63
231
953
356
C2 test for independence = 12.272, P = 0.007
1309
Bark Reaction
• High incidence of Bark Reaction NOT expected.
Mean of family means
SP
WWP
% BR in screening
13.2
28.4
% BR in field
60.9
25.4
0.336
-0.270
Correlation
Discussion
• Reason for high incidence of BR unknown.
• Hunt (1997) isolated several different fungi types
from BR phenotypes in WWP.
– Most common was phoma wilt (Phoma herbarum),
which produces lesions identical to BR
• BR has been shown to be real and repeatable.
• Other confounding biological or environmental
factors causing high level of BR.
Conclusions
• SP more susceptible than WWP at this site.
• Significant differences between species exist for
infection percentage, height, and number of
cankers/tree.
• Significant differences among families within a
species exist for infection percentage, and height
only.
Conclusions
• Both species exhibit moderate levels of BR.
• A significant association exists between species and
infection type.
N
PBR
BR
SP
< exp.
< exp.
> exp.
WWP
> exp.
> exp.
< exp.
• Low correlation between family mean BR % in screening
and field site.
Future Assessment
• 5th year measurements currently under way.
• Differential rates of mortality following infection.
• Long term differences in BR and tolerance
between species and families with species.
• Essential validation of results of artificial
inoculation tests.
• Information on current gains in rust resistance
from seed orchards.
Acknowledgements
• Dean Davis, and Deems Burton.
• Dr. B. B. Kinloch and Dr. R. Westfall
• Lee Riley, Jude Danielson, Bob Danchok, Sally
Long, and Ann Willyard.
• USDA Forest Service, Forest Health and
Protection Program