Assessment of the Rate of Progression of Butternut Canker in Vermont
D.R. Bergdahl, T.F. Schmalz, D. Ruddell, H.B. Teillon, and S. Halik
University of Vermont, Burlington, Vermont 05405, dale.bergdahl@uvm.edu
Introduction
Scj present
Scj absent
a
a
Percent change (1996-2002) in butternut mortality,
SCJ infection, Armillaria root rot, other root rot, and
heart/trunk rot in northcentral Vermont.
a
b
b
Developed Armillaria root Developed other root rots Developed heart/trunk rot
rot
Percent of trees
Percent of trees
a
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Percentage affected
2002
Percentage affected
1996
Mortality
SCJ Present*
Armillaria root Other root rots* Heart/Trunk
rot*
Rot*
* Data apply to trees living in 2002 only
Mortality
Scj infection
Other root rot
infection
Armillaria
root rot
infection
Heart/trunk
rot infection
20%
Conclusion
WR1
WR4
Overall mean
RD2
WN2
OS3
WM2
LE2
OS1
FN1
OE3
EX1
CN8
Plot
Plot
Butternut canker is increasing mortality of
butternut in Vermont. The occurrence of
secondary pathogens is further reducing tree
health leading to premature mortality. Based on
our mortality prediction curve, about 85% of all
butternut trees in Vermont are expected to die by
2011. We must make an effort to retain and
conserve all healthy appearing trees that may
form the foundation for future selection and
breeding programs designed to restore butternut
to the eastern hardwood forest.
CN6
0%
CN4
10%
WR4
WR1
WN2
RD2
OS3
WM2
OS1
OE3
LE2
FN1
EX1
CN8
CN6
CN4
CN2
CN14
CA3
CN12
CN10
CA1
AN3
0%
AN1
10%
30%
CN2
20%
40%
CN14
30%
CN12
40%
45%
50%
CA3
50%
60%
CA1
60%
70%
CN10
70%
80%
AN3
80%
90%
AN1
Percent butternut tree mortality
90%
BN1
On re-evaluation of original permanent plots, SCJ infection and butternut mortality had increased
to 96% and 41%, respectively, by 2002. Trees that exhibited main stem and root cankering in 1996
were more likely to be dead in 2002 and have Armillaria root rot and other root rots when
compared to healthy trees, especially in understocked stands. Suppressed trees were most likely to
die, but dominant trees had highest rates of root and trunk rots.
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
Suppressed Trees
100%
Location of Butternut
Plots Throughout
Vermont
2001-2004
Results
Comparison between SCJ-positive and SCJ-negative living
butternut trees (1996) developing Armillaria root rot, other
root rots and heart/trunk rots during the interim period 19962002. Letters indicate significant differences at 0.05 level.
Intermediate Trees
BN1
2001-2002 plots
2003-2004 plots
Co-dominant Trees
Projected mortality of butternut in Vermont based on
1996 and 2002 data. Mortality prediction given by
equation Y=mX+b, where Y=estimated percent
mortality at time X (in years from 1996), m=slope of
the line (0.04833), and b=0.12.
100
90
80
70
60
50
40
30
20
10
0
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
Legend
Dominant Trees
During 2003-2004, an additional 24 plots (1054 trees) were assessed. All trees were found
infected, and mortality was 49% (range 5-81%, mean 44% on a plot basis). Combining all 45
plots (2325 trees) throughout Vermont, overall SCJ infection and butternut mortality levels
were 86 and 45% respectively (2001-04 data).
Percent trees infected with SCJ
All trees were recorded by GPS location and included in a GIS
database. Individual tree information included: DBH, height, crown
class, crown diameter, and data on crown condition per FHM
guidelines, epicormic branching, root and stem cankering, and
presence of rot. All trees in the original data set were re-evaluated,
and new plots and trees were added (2001-04) to assess butternut
health in all counties of Vermont.
A diseased butternut with
extensive dieback and epicormic
branching in northern Vermont.
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Percent of butternut trees
Methods
Percent of butternut trees
The butternut canker fungus (Sirococcus clavigignenti-juglandacearum Nair, Kostichka, and
Kuntz) (SCJ) is believed to be an exotic pathogen that has seriously impacted butternut (Juglans
cinerea) throughout its range in eastern North America. In the Northeast, limited information is
available on the health status of butternut because this species is not significantly represented in
the national forest health monitoring (FHM) network of plots.
During 1993-96, Vermont established 18 permanent plots, evaluated 1317 butternut trees, and
found 94% were cankered and mortality was 12%. Reduced crown vigor and secondary
pathogens (esp. Armillaria sp.) were associated. Vermont’s permanent database is a valuable
resource for monitoring butternut canker incidence and severity and rates of tree mortality over
time. This information helps to better understand butternut canker and to develop new
guidelines for management of butternut.
Comparison of 2002 mortality, SCJ infection, Armillaria root rot, other root rot, and
heart/trunk rot rates classified by crown class. Differences among crown classes in
mortality, other root rot, and heart/trunk rot were significant at the 0.05 level.
Year