Searching for evidence of thousand cankers disease in national
forest inventory data collected in Tennessee
KaDonna Randolph :: U.S. Forest Service :: Southern Research Station FIA :: Knoxville, TN 37919 :: krandolph@fs.fed.us
FHM Evaluation Monitoring Project SO-EM-B-11-01
Background
Results
• The walnut twig beetle (WTB) (Pityophthorus juglandis) has been
identified in six Tennessee counties.[1]
Most plot averages were in the range of normal and healthy with no
obvious clustering of poor crown conditions.
• Thousand cankers disease (TCD) results when Geosmithia morbida
spores on the wings of the WTB are introduced into black walnut
trees.[2] Multiple cankers around the point of infection lead to branch
dieback.[3]
P3 plot
Black walnut crown conditions were generally within the normal range for
hardwood trees.
P2 urban plot
County boundary
TCD quarantine area
* Knox County, initial discovery of TCD
Crown Density
30
Black walnut
25
Percent crown density
0 – 35
36 – 45
46 – 100
• Symptoms of TCD may take many years to develop. Trees typically die
within 2 to 4 years after symptoms are visible.[3]
20
Percentage
of trees
All hardwoods
15
10
*
5
0
• TCD may have been present in Tennessee 10 to 20 years prior to its
discovery in 2010.[4] If so, evidence of its presence might exist in the
data collected by the U.S. Forest Service Forest Inventory and Analysis
(FIA) Program.
<20
25 30 35 40 45 50 55 60 65 >70
Percent crown density
Crown Dieback
100
Percent crown dieback
0–5
6 – 20
21 – 100
Black walnut
80
Percentage
60
of trees
Objectives
*
All hardwoods
40
• Analyze past black walnut crown conditions assessed in Tennessee to
determine if symptoms of TCD were present.
20
0
0
• Locate areas that have black walnut trees with poor crown conditions
that might suggest the presence of TCD.
• Evaluate the effectiveness of the U.S. Forest Service Forest Inventory
and Analysis (FIA) Program plot network for detecting localized forest
health problems.
Percent foliage transparency
0 – 20
21 – 35
36 – 100
>25
5
10-20
Percent crown dieback
Foliage Transparency
50
All hardwoods
40
Percentage
of trees 30
*
Black walnut
20
10
Data and Methods
0
• Collected in Tennessee by the Southern FIA Program, 2005 to 2009.
• FIA level of data collection
• Phase 2 (P2) – Basic forest inventory plot
• P2 Urban – P2 plot in a designated urban area
• Phase 3 (P3) – P2 plot designated for forest health monitoring
• Trees with diameter at breast height > 5.0 inches
• Tree status (live or dead)
• Cause of death
• Crown density, crown dieback, and foliage transparency
Black walnut’s infrequent occurrence across the landscape along with the
P3 sampling intensity limit the number of crown condition observations.
2765 forested P2 plots in Tennessee
17 P3 plots with live
black walnut trees,
with an average of
1.4 live black walnut
trees per plot.
168 P3 plots
<10
>35
15
20
25
30
Percent foliage transparency
Conclusions
• Across the state, black walnut crown conditions are within the range of
what is typically considered normal and healthy for hardwood trees.
• Given the distribution of recent mortality, Middle Tennessee may be an
area for special WTB and TCD surveys.
• The absence of TCD symptoms in the FIA crown condition data could
be due to their actual absence or to an insufficient monitoring system for
detecting their presence.
Density outline
Crown density–percentage
of light blocked by all
crown biomass through the
projected crown outline.
Recent black walnut mortality was concentrated in Middle Tennessee.
Vegetation was the most frequently recorded cause of death, 2005 to 2009.
Dieback
[2]
Crown dieback–recent
mortality of branches with
fine twigs.
Transparency outline
Literature cited
[1] TN.gov Newsroom (2011). http://news.nt.gov/node/7691
Foliage transparency–
percentage of light visible
through the live, foliated
portion of the crown.
vegetation
disease
weather
insect
unknown
County boundary
TCD quarantine area
silviculture/land clearing
* Knox County, initial discovery of TCD
L.P. Newton and others (2009). http://mda.mo.gov/plants/pdf/tc_pathwayanalysis.pdf
[3] M.A.
Hansen and others (2011). http://www.ppws.vt.edu/~clinic/alerts/07-22-11_TCD_alert.pdf
[4] G.
Haun and others (2010).
http://www.tn.gov/agriculture/publications/regulatory/TN_TCD_ActionPlan.pdf
*
“Vegetation” includes competition,
suppression, and vines/kudzu,
and was recorded for 12 trees.
Funding
Funding for this project was provided by the U.S. Forest Service Forest Health
Monitoring Program and U.S. Southern Forest Inventory and Analysis Program.