FIA OZONE BIOMONITORING PROGRAM

1
FIA OZONE BIOMONITORING PROGRAM Ozone Symptom
Identification Identifying Characteristics of
Ozone Bioindicator Species Prepared By Gretchen
Smith, FIA National Ozone Advisor Ron Kelly and
Jay Lackey,Vermont Department of Forests and
Parks. This presentation is intended to be used
by new and returning crews as a training tool.
There are images of each bioindicator species,
some with classic symptoms of ozone injury and
some with mimicking symptoms. Each slide has been
annotated to focus attention on certain
diagnostic symptoms that may clarify what ozone
injury does and does not look like in the field.
Keep in mind that these are images of dried leaf
samples. Injury on fresh, live plants may be
slightly different in color and appearance. Crew
reminder If you are uncertain if a leaf injury
symptom is caused by ozone exposure, please rate
the plant as if it was ozone injury and send in a
leaf sample for QA review. Use a plant press to
prepare quality leaf vouchers. Leaves should be
labeled and pressed on blotter paper with no
overlap to preserve the injury symptoms. The
following codes are used on each
slide Species codes blackberry
915 black cherry 762 and pin cherry
761 common and tall milkweed 365 white ash
541 (other ash species such as green
ash are sometimes substituted) spreading dogbane
366 (erect dogbane is sometimes
substituted) big leaf aster 364 sassafras
931 yellow poplar 621
OZONE INJURY
NOT OZONE, A MIMICKING SYMPTOM

2
BLACKBERRY 915 Identifying characteristics of
Common Blackberry (Rubus allegheniensis) Leaves
alternate, palmately compound with 3 to 7
leaflets, averages 5, the middle leaflet tends to
have a stalk and averages 31/4 to 5 in length.
Upper leaf surface dark green, smooth to slightly
pubescence, Lower surface green with velvety
pubescence. First-year (non-flowering) canes are
greenish to greenish-red, second-year (flowering)
canes brown. Both first- and second-year canes
are star-shaped and ridged, with stout prickles
along the stem. Flowers borne in clusters, with
small leaves at the base and gland-tipped hairs
along the stalk, appearing from April through
July. Fruit is dark violet to black, juicy,
plump, and sweet, about ¾ long appearing June
through August.
leaflet
Flower
arching branches
Stout prickles
3
Typical ozone injury symptoms on blackberry
visible as red, interveinal pigmentation on the
older foliage.
4
Classic purple-red ozone stipple occurring
between the leaf veins and visible only on the
upper-leaf surface.
915
Ozone stipple
This is a single leaf of blackberry. A perfect
leaf voucher consists of 3 leaves that have been
pressed flat and that show obvious ozone injury
symptoms, just like this one.
5
915
Ozone stipple
Classic upper-leaf surface ozone stipple on
blackberry. Note the purple-red color of the pin
cushion like lesions. The leaf margins and veins
remain relatively green. The undersurface of
these leaves are free of insect or pathogen
infestation.
6
915
Ozone stipple
Classic ozone injury on blackberry. The photo
image has caused some reddening of the leaf
stipple. To the naked eye it is a darker
purple-red than what is shown here. Note the
line of green tissue along the leaf margins and
the absence of injury symptoms where leaf overlap
occurred.
7
Classic red-brown, interveinal ozone stipple on
blackberry. Viewed with a hand lens, both large
and small veins remain green. The
undersurface of this leaf is entirely free of
injury symptoms.
915
Ozone stipple
8
The underside of these leaves are covered with
the dusty spores of the blackberry rust fungus.
The upper-leaf surface discoloration is a uniform
dark red that includes the smaller leaf veins and
is not typical of ozone injury.
This is not ozone injury.
9
915
This is not ozone injury. There are too many
confounding symptoms visible on this leaf sample.
Smaller lesions surrounded by green halos
Bifacial, large brown lesions that cross leaf
veins and involve leaf margins
Ozone-like stipple which under magnification has
bleached white centers
10
915
Brown discoloration is not typical of ozone
injury.
This is not ozone injury.
Bifacial, fungal-type lesions are abundant on the
leaf surface.
11
This is not ozone injury This looks so much like
ozone injury in the field that crews should
collect this injury type and send it in for
review by an expert.
This is an example of a leaf with questionable
ozone symptoms. With a hand lens, it is possible
to see that the discoloration bleeds into all the
smaller veins of the leaf. There is little
classic ozone stipple. The injury appears
concentrated at the leaf margins.
12
This is not ozone injury.
915
This leaf sample may have been placed on top of
another leaf in the plant press causing leaf
moisture to obscure any ozone stipple. Leaf
color is gray to brown with no evidence of
typical ozone injury symptoms.
13
This is not ozone injury.
915
Under magnification, there is no evidence of
discreet ozone stipple on this leaf surface. The
large necrotic areas are uniform in color.
The leaf tissues appear to have
been scorched by very hot weather.
14
This is not ozone injury.
915
Closer view of what appears to be leaf scorch
caused by exposure to very hot, dry weather.
15
915
This is not ozone injury.
The color and injury pattern are not
characteristic of ozone stipple. The undersurface
of this leaf is covered with the cast skins and
cottony filaments of an insect infestation. The
visible injury is probably due to insect feeding.
16
This is not ozone injury.
915
Closer view of a leaflet of blackberry that has
many different lesions and scratches and some
general discoloration, but no obvious sign of
ozone injury.
17
This is not ozone injury.
915
These ring spot lesions are not typical of ozone
injury. Under magnification, the discolored rings
can be seen to cross leaf veins. Other scattered
brown lesions show an atypical injury pattern. No
classic ozone stipple is visible..
18
BLACK CHERRY 762
Identifying Characteristics of Black Cherry
(Prunus serotina) Leaves are 2 to 6 in length
and 1 ¼ to 2 in width with finely serrated
teeth on the margins, dark green and shiny on
top with a paler green below. The midrib is
prominently fringed beneath with white to brown
hair. Fruit is a drupe that is arranged along
a spreading or drooping axis at the end of a
twig. The twigs have a bitter-almond smell and
taste. Bark on younger trees is gray and smooth,
reddish brown to nearly black, with conspicuous,
narrow, horizontal lenticels. On older trees the
bark is exfoliating in small, shiny, platy scales
with upturned edges. Leaves of choke cherry, a
similar species, have a hairless midrib beneath
and are sharp toothed. Leaves of pin cherry are
are longer and narrower with finely serrated
margins.
Brown fringe along midrib
leaves
19
Classic ozone injury symptoms on a black cherry
seedling. Note how the red-brown stipple is more
pronounced on the mid-aged and older foliage.
Ozone stipple
20
severe stippling
762
light stippling
Ozone stipple
no obvious stippling
moderate stippling
Classic distribution of ozone injury symptoms
along a branch stem. Leaves toward the branch tip
remain green those toward the base of the branch
show pronounced stippling.
21
762
The bleached stippling along the leaf veins may
be attributable to leaf hopper feeding.
Ozone stipple
Ozone stipple
Classic ozone stipple on leaves that have also
been heavily chewed, along the margins, by
insects.
22
762
Leaf voucher label has been attached to all 3
leaves and labeled correctly with the identifying
codes for state, county, hex number, plot number,
data collection date, and species.
Ozone stipple
State 42 County 07 HexNum 4107911
PlotNum 1 Date 8/12/02 Species 762
Classic upper-leaf surface purple stippling. Note
absence of stipple along mid-vein. Note how the
major veins, leaf margins and general background
of the ozone injured leaves remain green.
23
762
Purple-red ozone stipple accompanied by larger
brown lesions of unknown origin and some small
white lesions typical of a leaf sucking insect.
The ozone induced red coloration may appear to
bleed through the smaller veins and be faintly
visible on the leaf undersurface.
Ozone stipple
Bleached stippling
Large brown lesions with darkened margins.
Lesions cross all veins.
24
762
Classic interveinal ozone stipple. Note how fine
the stippling is compared to the more blotchy,
aggregated lesions that are visible on the
previous slide. Some insect damage is also
visible.
Ozone stipple
Ozone stipple
25
Leaves injured by ozone eventually lose much of
their green color. Voucher leaf samples collected
for QA review for ozone injury should be
relatively green.
Ozone stipple
Good leaf samples
Poor leaf samples Ozone injured leaf is
exhibiting premature senescence and has lost most
of its chlorophyll.
26
This is not ozone injury.
762
large lesions with apparent fungal fruiting
bodies visible under magnification
possible ozone stipple
These two leaves are dominated by large,
bifacial, necrotic lesions that cross leaf
margins and veins, and brown discoloration along
the mid-rib. There is also scattered ozone-like
stippling visible on the upper-leaf surface. The
amount and degree of confounding injury symptoms
make it difficult to assess ozone injury. Crews
may be uncertain whether or not to rate any or
all of these symptoms as ozone-induced. When
uncertain, rate the ozone-like stipple as ozone
injury, ignore larger, atypical lesions, and
collect leaf samples for QA review.
27
762
This is not ozone injury.
This is an example of an ozone-like leaf injury
that should be collected as possible injury even
though it does not fit the classic injury pattern
for ozone stipple. This leaf sample was not
validated as ozone injury by the post-season QA
review. Under magnification, the lesions appeared
to regularly cross leaf veins. This, taken
together with the atypical injury pattern, caused
the sample to be considered too uncertain for
ozone injury.
28
Normal sized leaf sample
Always collect normal sized leaves for the leaf
vouchers. Avoid undersized leaves. Ozone-like
stipple is visible on these undersized leaves of
black cherry. There is disagreement amongst the
experts as to whether ozone-like stipple on
undersized leaves is attributable to ozone or is
evidence of a non-specific stress response.
This is not ozone injury.
Undersized leaves are often found at the base of
leaf branches in the inner crown.
762
29
Identifying characteristics of Common Milkweed
(Asclepias syriaca) All parts of Common
Milkweed exude latex when cut. Leaves
opposite, or whorled. Twice as long (2 to 12)
as they are wide, with smooth margins and stems
with latex. Upper leaf surface can be smooth to
slightly hairy, lower densely hairy. Petiole is
short and thick. Flowers borne in large clusters
on stalks in the upper leaf axils. They appear
rose or greenish-white, from June to
August. Fruit is a large comma shaped
pod. Monarch butterflies are a common sight on
milkweed.
Left photo Common milkweed Right photo Tall
milkweed
MILKWEED 365
30
Classic ozone injury symptoms on common
milkweed. Note how the ozone stipple is more
pronounced on the mid-aged and older foliage.
Leaves at the top of the plant remain
green. Towards the end of the growing season, the
yellow, injured leaves at the base of the plant
will drop off prematurely.
31
365
Dark pigmented stipple on the upper leaf surface
of milkweed. The veins and veinlets remain green
as do the leaf margins.
Ozone stipple
32
Close-up view of ozone stipple on green milkweed
tissue.
33
365
Another good example of classic ozone stipple on
common milkweed. The undersurface of this leaf is
entirely green and free of any injury symptoms.
Ozone stipple
These tears in the leaf tissue are unrelated to
ozone injury.
34
365
This is a good example of a leaf voucher for
milkweed. A voucher consists of 3 leaves that
clearly show the ozone injury symptom. The
stippling shown here is classic ozone stipple. A
petiole label has been attached to the leaves to
identify the ozone biosite where these leaf
samples were collected.
Ozone stipple
State 42 County 13 HexNum 4107814
PlotNum 02 Date 7/30/03 Species 365
Labels may be attached to individual leaves or to
a set of leaves as is shown in this slide.
35
This is an example of ozone injury on tall
milkweed, a plant that is closely related to
common milkweed. The pigmented stipple is very
similar to that found on common milkweed. The
dark black stipple occurs on the upper leaf
surface and has a pin cushion-like appearance.
365
Ozone stipple
Ozone stipple on tall milkweed
Both Tall and Common Milkweed are bioindicator
species. Use species code 365 for both.
36
365
The stippled areas on the top leaf are surrounded
by a yellow halo. The lesions show through to
the underside of the leaf. The injury pattern is
not typical of ozone stipple.
This is not ozone injury.
The discoloration on the bottom leaf may be
attributable to hot, dry weather. No ozone
stipple is apparent.
This is not ozone injury.
37
On the top leaf, the stipple-like symptom clings
to the leaf veins. Under magnification, many
veins are discolored. The injury pattern is not
typical of ozone injury.
365
This is not ozone injury.
The gray-brown discoloration on the lower leaf
may be due to improper voucher handling. If
leaves are placed on top of each other in the
plant press they will discolor in this way. Ozone
injury could not be validated on this leaf sample.
38
365
The injury pattern of the bleached and darkened
tissues on this leaf sample are not typical of
ozone injury. Under magnification, a stipple-like
symptom is visible, but the lesions are not
interveinal. The veins are discolored in the
damaged areas.
This is not ozone injury.
39
The most obvious symptoms on this leaf sample are
the blotchy red lesions that appear to bleed
into the surrounding tissues. These lesions are
bifacial and can be seen to cross the leaf veins.
Under magnification, many smaller superficial
black spots are visible on the leaf surface. The
color and distribution of these smaller spots are
not typical of ozone injury.
365
This is not ozone injury.
blotchy red lesions
scattered small black spots
40
365
With a hand lens, the discolored areas on this
sample look like ozone stipple. However, the
discolored lesions occur both on and between the
large and small veins of the leaf and are
surrounded by lightly discolored areas that are
not stipple-like. These symptoms do not fit the
pattern of classic ozone injury on milkweed.
This is not ozone injury.
Crews that encounter these symptoms on milkweed
in the field may be uncertain whether or not to
rate this as ozone injury. Even with a hand lens,
it is difficult to be certain. When there is
doubt, rate the injury as ozone and collect leaf
samples for expert review.
41
WHITE ASH 541
Identifying characteristics of White ash
(Fraxinus americana) Leaves are opposite and
compound. Generally have 5-9 leaflets that are 2
½ to 5 long. Twigs are round, shiny, mostly
hairless. Buds are inset in the leaf scar. Bark
is ashy gray, on older trees it becomes finely
furrowed into close diamond-shaped areas
separated by narrow interlacing ridges.
Green ash buds are set above the leaf scar.
White ash buds are inset in the leaf scar.
42
Classic purple-red ozone stipple on ash. The
stippling occurs between the major veins on the
upper-leaf surface. The undersurface of the leaf
is green and entirely free of injury.
Ozone stipple
Dark brown lesion with a pale necrotic center -
unrelated to ozone injury.
43
Closer view of typical ozone stipple on an ash
leaflet. Note the line of green tissue along the
margins of all major leaf veins. Pigmented
stippling is contained within the smaller veins
of the leaf.
541
Ozone stipple
Ash leaves are compound. This is a single leaflet
taken from a compound leaf. An acceptable ash
leaf voucher consists of 3 entire leaves of ash,
not 3 leaflets.
44
541
Ozone stipple
Severe ozone stippling on white ash. The lesions
are dark purple-red in color and, under
magnification, can be seen to be contained
within the leaf veins. The undersurface of this
leaf is clean and green.
45
541
This is not ozone injury.
Darkened lesions cover the leaf surface, often
darkest along the midrib and other major leaf
veins. This is not typical of ozone stipple.
With a hand lens, it is possible to see white
necrotic centers scattered throughout the
discolored areas that may be attributable to
insect feeding. There is honeydew and other
evidence of insect activity on the undersurface.
The leaf is generally messy and damaged by a
variety of factors..
Ozone-like stipple visible along the edges of the
heavily chewed tissues is assumed to be a
response to a biotic stress agent, not ozone.
46
541
The white to tan lesions visible on this leaf are
characteristic of feeding activity by the ash
plant bug. The undersurface of the leaf is
covered with plant bug excrement.
This is not ozone injury.
47
This ash leaf is infected with the ash ring spot
virus. The reddened tissue is probably a result
of virus infection and cannot be validated as
ozone injury. Under magnification, the stippling
appears less distinct than classic ozone stipple.
541
This is not ozone injury.
48
541
This is not ozone injury.
Large brown lesions have a tan necrotic center
and are outlined by dark pigmented tissue. A fine
stippling, similar to ozone injury, is visible in
the surrounding tissue. This cannot be attributed
to ozone due to the confounding presence of the
more dominant stress agent.
ozone-like stipple
49
541
This is not ozone injury.
It is difficult to see without magnification, but
the purple stippling visible on this leaflet has
an atypical injury pattern for ozone. It tends to
cling to the leaf veins. Injury along the vein is
characteristic of insect feeding, not ozone.
50
This is not ozone injury.
Similar to the injury on the preceding ash
leaflet, the stippling symptom visible here
clings to the leaf veins. This produces a lined
injury pattern that is not typical of ozone
injury.
Note that the darkest stippling occurs along the
leaf margins and tips. This is not typical of
ozone injury.
541
51
This is an example of a questionable leaf
voucher. Leaves with similar symptoms should be
collected and sent in for expert review. The
discoloration is diffuse with no obvious stipple.
It is darkest at the leaf margins. The symptoms
are very similar to normal Fall coloration.
541
52
541
Leaf bronzing possibly due to exposure to hot,
dry weather. The injury color and pattern are not
typical of ozone injury.
This is not ozone injury.
53
DOGBANE 366
Identifying characteristics of Spreading Dogbane
(Apocynum androsaemifolium) All parts exude a
milky juice when broken. Leaves opposite, oval,
oblong, or egg-shaped, with smooth margins and
red stems. Dark green above, pale beneath, 2 to
3 long. Flowers small, pink, bell-shaped, with
pink stripe in the center. Flowers appear from
mid-June through August. Fruit a narrow, long
pod with many seeds. Each seed has a long tuft
of cottony hairs.
Top and right photo Spreading dogbane Far right
photo Erect dogbane
54
Classic upper-leaf surface ozone stipple.
Note that the leaves are otherwise relatively
green and healthy. The most severe stippling is
towards the base of the plant stem.
366
Ozone stipple
Light and scattered ozone stipple on the younger
leaves
Note the more pronounced stippling on the older
leaves. Veins remain green.
55
Typical, dark brown to black, interveinal ozone
stipple on dogbane. These leaves are so thin that
the discoloration may be visible from the
underside of the leaf.
Ozone stipple
366
56
366
The brown color of these necrotic areas are not
typical of ozone injury.
This is not ozone injury.
The injury pattern (follows the leaf veins) and
color of these lesions is not typical of ozone
injury.
57
366
This is not ozone injury.
Clusters of necrotic lesions, especially along
the leaf margin, are not typical of ozone injury.
58
366
This is not ozone injury.
The large brown lesions with a yellow margin
visible on these 2 leaves are not symptomatic of
ozone injury. On the smaller leaf it is possible
to see ozone-like stipple on the leaf surface.
However, because this stipple emanates from the
larger fungal-type lesions, we can not consider
this an ozone response.
ozone-like stipple
fungal-type lesions
59
This type of injury can be quite common on
spreading dogbane. It is NOT ozone injury. The
lesions are large and brown and surrounded by
yellow tissue. No classic ozone stipple is
visible.
60
BIG LEAF ASTER 364
Identifying characteristics of Big Leaf Aster
(Aster macrophyllum) Leaves are 4 to 8 in
width, heart-shaped, with unevenly toothed
margins. Leaf stem is purplish and nearly as
long as the length of the leaf. Flowering stalk
can reach 5 in height. Flowers range in color
from pale lavender to violet to light blue and
are evident from August to September.
61
364
Classic ozone stipple on big leaf aster. The
stippling appears dark brown to black on the
dried leaf samples. It is distinctly interveinal.
There is no visible injury or discoloration on
the undersurface of the leaf.
Ozone stipple
Larger, brown lesions are unrelated to ozone
injury.
62
364
Ozone stipple
Dark pigmented ozone stipple. With a hand lens,
it can be seen that the pin cushion like stipples
are entirely contained by the leaf veins.
63
364
This is a questionable leaf sample for ozone
injury. The pigmented stippling is not as dark as
in the previous slides of aster. It also appears
to cling to the leaf veins. Leaves like this
should be rated as ozone and then collected for
expert review of the leaf symptoms.
64
364
This is not ozone injury.
These large dark lesions of unknown origin are
bifacial and appear to cross the smaller veins of
the leaf.
65
364
The tan stippling on this leaf sample obviously
clings to the leaf veins as is characteristic of
feeding injury caused by a phloem sucking insect.
Insect excrement is visible on the undersurface
of the leaf.
This is not ozone injury.
66
SASSAFRAS 931
Identifying characteristics of Sassafras
(Sassafras albidum) Three leaf types 1) entire
and somewhat elliptical, 2) mitten-shaped, 3)
three-lobed. All three leaf types can be found
on the same tree. Twigs and leaves have a spicy
odor and taste. Fruit is a blue drupe. Bark is
red-brown, thick, furrowed and aromatic.
67
Classic ozone stipple on sassafras. Note how the
red-brown stipple is more pronounced on the older
foliage. Major leaf veins remain green.
68
Ozone injury on sassafras in the field is often
described as leaf bronzing rather than leaf
stippling. The injury pattern is clearly
interveinal. The color on pressed leaf samples
appears more brown or tan than purple-red.
Ozone stipple
931
leaf bronzing
69
Closer view of the bronze lesions characteristic
of ozone injury on sassafras.
931
Ozone stipple
Larger zones of necrotic tissue are unrelated to
ozone injury.
70
Ozone stipple
Photo Credit Diagnosing Injury to Eastern
Forest Trees - Manual for Identifying Damage
Caused by Air Pollution, Pathogens, Insects, and
Abiotic Stresses. Skelly, J.M. et al., 1987.
Available from Publications Distribution Center,
Pennsylvania State University.
Pigmented ozone stipple on sassafras at a field
site used for biomonitoring.
71
Leaf sample with circular clusters of small
pigmented spots that suggest infection by a
biotic pathogen. This type of injury pattern is
not characteristic of ozone injury.
931
This is not ozone injury.
72
SWEETGUM 611
Identifying characteristics of Sweetgum
(Liquidambar styraciflua) The leaves are
star-shaped, deeply and palmately 5- to 7-lobed.
Margins are finely serrated. Leaf surface is
bright green above pubescent in axils of the
veins below somewhat fragrant when crushed.
Fruit is a 1 to 1 ¼ spiny ball, often
hanging. Twigs are shiny, green to yellowish
brown, somewhat fragrant when crushed. Bark is
grayish brown deeply furrowed into narrow, flaky
ridges.
73
Classic purple-red ozone stipple on sweetgum
611
Ozone stipple
Small pigmented stippling occurs between the
large and small veins of the leaf. When stippling
is severe, the color may be faintly visible on
the undersurface of the leaf.
Darker pigmented lesions with lighter centers
tend to sit on the leaf veins. They are
unrelated to ozone injury.
74
The leaf undersurface is free of ozone injury.
Ozone stipple
State 3907365 County 04 HexNum 3008636
PlotNum 1 Date 8/19/03 Species 611
A well prepared leaf voucher consists of 3 leaves
that clearly show the upper-leaf surface
pigmented stipple characteristic of ozone injury
on sweetgum. All samples must be identified by
state, county, hex number, and plot number, as
well as sample date and species code.
75
611
Ozone-induced pigmented stipple on sweetgum.
The larger, darker spots are not ozone injury.
Ozone stipple
76
611
The scattered ozone stipple on this leaf sample
has a red-black color under magnification. The
larger blotches of discolored tissue are not
characteristic of ozone injury.
Ozone stipple
77
611
To the naked eye, ozone injury on this leaf
sample appears as a general discoloration of the
upper-leaf surface. With a hand lens, the pin
cushion like stippling characteristic of ozone
injury is clearly visible. Veins remain clear or
green in color.
Ozone stipple
Photo Credit for Inserted Image on Right
Diagnosing Injury to Eastern Forest Trees -
Manual for Identifying Damage Caused by Air
Pollution, Pathogens, Insects, and Abiotic
Stresses. Skelly, J.M. et al., 1987. Available
from Publications Distribution Center,
Pennsylvania State University.
78
611
This sample shows large blotches of discolored
tissue. The lesions are bifacial and cross both
large and small veins. This injury pattern is not
typical of ozone injury.
This is not ozone injury.
79
611
This is an example of a questionable leaf
voucher. There is a diffuse ozone-like stipple
across much of the upper leaf surface. There are
also numerous large, bifacial, pigmented lesions
with necrotic centers scattered across the leaf,
along the margins, and on the leaf veins. The
leaf symptoms are complex. Rate the leaf as
ozone injury, collect leaf voucher samples, and
mail them in for expert review of the injury
symptoms.
80
611
This is not ozone injury.
With a hand lens, it is possible to see that the
brown stippling on this leaf sample clings to the
leaf veins. Some of the veins are discolored.
This is not typical of ozone injury.
81
YELLOW POPLAR 621
Identifying characteristics of Yellow-poplar
(Liriodendron tulipifera) Leaves are 4 to 6 in
diameter. Usually has 4 lobes, 2 at the tip and
2 at the side, with smooth margins. Squarish at
the base. Fruit is an erect cone-like aggregate
of samaras. Flowers are cup-shaped with 6 petals,
resembling tulip. Twigs stout, bitter to taste
with diaphragmed pith. Bud shaped like a ducks
bill. Bark on young trees is dark green and
smooth, with small white spots. On older trees
it has interlacing rounded ridges separated by
ashy-gray fissures.
82
Ozone stipple
Photo Credit Diagnosing Injury to Eastern
Forest Trees - Manual for Identifying Damage
Caused by Air Pollution, Pathogens, Insects, and
Abiotic Stresses. Skelly, J.M. et al., 1987.
Available from Publications Distribution Center,
Pennsylvania State University.
Dark pigmented stipple on the upper leaf surface
of yellow poplar at an ozone field site.
83
Classic pigmented stipple occurs between the leaf
veins on the upper leaf surface. The
undersurface of the leaf is free of insect and
pathogen activity. Pressed leaf samples of
yellow poplar can be difficult to read because
the samples often discolor in storage. Leaves
that have not been pressed properly, or are
otherwise difficult to read, cannot be validated
for ozone injury.
621
Ozone stipple
Classic ozone stipple on yellow poplar
84
621
Upper leaf surface ozone stipple. On pressed
samples the stippling appears dark brown to
red-black.
Ozone stipple
85
621
Severe ozone stipple is evident on this leaf
sample. The injured areas are bounded by the
smaller veins of the leaf.
Fungal-type lesions are visible on this leaf
sample. They are unrelated to ozone injury.
Ozone stipple
86
621
With a hand lens, classic pigmented stipple is
readily visible on this leaf sample. The large
circular lesions are unrelated to ozone injury.
87
621
Scattered dark lesions are visible. They are
large and bifacial. They are not typical of ozone
stipple.
88
The visible leaf injury on this sample may be due
to multiple stress agents. The symptoms are
complex. The leaf undersurface is also
affected. No classic ozone stipple is apparent.
621
This is not ozone injury.
General discoloration due to improper voucher
handling.
Large, bifacial lesions
89
PIN CHERRY 761
Identifying characteristics of Pin Cherry
(Prunus pensylvanica) Leaves alternate, long,
narrow, finely serrated, 2 to 5 in length, 1
to 1 ½ wide, yellow-green less shiny than those
of black cherry. Flowers white, 5 to 7 in small
flat-topped clusters. Occurring from March to
July. Fruit a round, red, sour tasting drupe.
Occurring from July to September. Twigs slender,
smooth, reddish-brown. Twigs have a bitter
almond taste. Bark shiny, red-brown, with
horizontal orange lenticels.
90
Classic upper-leaf surface ozone stipple on pin
cherry.
761
Note red stipple, green veins and margins.
Ozone stipple
91
761
Classic pigmented stipple occurs between the
veins on the upper-leaf surface. Underside
remains green.
Ozone stipple
92
761
This is not ozone injury.
Scattered ozone-like stippling is visible on this
leaf sample. Under magnification the small
pigmented spots have tan necrotic centers that
may have been caused by a sucking insect.
Scattered ozone-like stippling
Necrotic areas of unknown origin.
93
Ozone-like injury has been observed in the field
on many species that are not on the target list
of ozone sensitive bioindicators used in the FIA
program. Until these species have been thoroughly
tested under controlled conditions in greenhouse
fumigation studies, they cannot be used as
bioindicators. Leaf samples of the species listed
below have been sent in, along with the standard
ozone vouchers, by FIA fields crews from many
states. This practice is appreciated by
University researchers involved in ozone
biomonitoring studies. The list of potential
bioindicator species1 includes red maple (Acer
rubrum), sycamore (Platanus occidentalis),
basswood (Tilia americana), sourwood (Oxydendrum
arboreum), wild plum (Prunus americana),
nannyberry (Viburnum lentago), wild grape (Vitis
spp.), winged sumac (Rhus copallinum), Virginia
creeper (Parthenocissus quinquefolia), Trumpet
creeper (Tecoma radicans), cup plant (Silphium
perfoliatum), woodland sunflower (Helianthus
hirsutus), blueberry (Vacinnium spp.), and
ironweed (Veronia noveboracensis)2. Other
species under investigation that have not been
specifically noted by FIA crews include pawpaw
(Asiminia triloba), red bud (Cercis canadensis),
catalpa (Catalpa speciosa), silver maple (Acer
saccharinum), boneset (Eupatorium perfoliatum),
and cone flower (Rudbekia laciniata)2. 1Native
species studied during the 2000 and 2001 summer
season at Pennsylvania State University,
University Park, PA. 2For more information
contact John Skelly at jms34_at_psu.edu and Art
Chappelka at chappe_at_forestry.auburn.edu
94
Red maple (Acer rubrum)
Ozone stipple
95
Wild Plum (Prunus americana)
96
Nannyberry (Viburnum lentago)
Ozone stipple
97
Viburnum spp.
98
Tall Milkweed (Asclepias exalta)
99
Basswood (Tilia americana)
Ozone stipple
100
Wild grape (Vitis spp.)
Ozone stipple
Fox grape (Vitis labrusca) has been tested and
found to be ozone sensitive under controlled
conditions. Although common in our area, it is
difficult to distinguish Fox grape from other
wild species of grape which may, or may not be,
ozone sensitive.
101
Sycamore (Platanus occidentalis)
Ozone stipple
102
Sourwood (Oxydendrum arboreum)
Ozone stipple
103
Cone flower (Rudbekia laciniata var. laciniata)
Left photo Stand of cone flower Bottom photo
close up of pigmented ozone stipple on the leaves
of cone flower
Ozone stipple
104
Virginia creeper (Parthenocissus quinquefolia)
Ironweed Veronia noveboracensis
Blueberries Vaccinium spp.
105
Ozone-like stipple on Robinia (locust) species.
Possible ozone injury on crownbeard.
Top Two leaves of crown beard, smaller one with
symptoms. Bottom Whole plant in natural stand
older leaves are symptomatic.
106
Ozone-like stipple on Silphium species.
107
Woodland Sunflower (Helianthus divaricatus)
108
Poison Ivy (Rhus radicans)
Dont take leaf samples from this plant!
109
Supplemental Species
Not official bioindicator species. Use as the
4th, 5th, or 6th species at a biosite. DO NOT use
to meet the requirement for 3 species per biosite.
Silver maple Boneset Pawpaw Woodland
sunflower Swamp milkweed Wild plum Trumpet
creeper Winged sumac Red bud Cup
plant Catalpa Iron weed Nannyberry Spicebush
Greenbriar Wild grape