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 = 915black cherry = 762; and pin cherry = 761common and tall milkweed = 365white ash = 541 (other ash species such as green ash are sometimes substituted)spreading dogbane = 366 (erect dogbane is sometimes substituted)big leaf aster = 364sassafras = 931yellow poplar = 621

OZONE INJURY =

NOT OZONE, A MIMICKING SYMPTOM =

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

Stout prickles

Flower

arching branches

Typical ozone injury symptoms on blackberry visible as red, interveinal pigmentation on the older foliage.

915 Classic purple-red ozone stipple occurring between the leaf veins and visible only on the upper-leaf surface.

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.

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.

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.

915

Ozone stipple

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

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.

Bifacial, large brown lesions that cross leaf veins and involve leaf margins

Smaller lesions surrounded by green halos

Ozone-like stipple which under magnification has bleached white centers

915 This is not ozone injury.

There are too many confounding symptoms visible on this leaf sample.

Bifacial, fungal-type lesions are abundant on the leaf surface.

Brown discoloration is not typical of ozone injury.915

This is not ozone injury.

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.

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 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.

915This is not ozone injury.

915Under 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.

This is not ozone injury.

Closer view of what appears to be leaf scorch caused by exposure to very hot, dry weather.

915This is not ozone injury.

915

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.

This is not ozone injury.

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.

915This is not ozone injury.

915

These ring spot lesions are not typicalof ozone injury. Under magnification,the discolored rings can be seen tocross leaf veins. Other scattered brownlesions show an atypical injury pattern.No classic ozone stipple is visible..

This is not ozone injury.

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.

BLACK CHERRY 762

Brown fringe along midribleaves

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

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.

severe stippling

moderate stippling

light stippling

no obvious stippling

762

Ozone stipple

762 The bleached stippling along the leaf veins may be attributable to leaf hopper feeding.

Classic ozone stipple on leaves that have also been heavily chewed, along the margins, by insects.

Ozone stipple

Ozone stipple

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.

762

State: 42 County: 07

HexNum: 4107911 PlotNum: 1

Date: 8/12/02 Species: 762

Ozone stipple

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.

762Purple-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

Large brown lesions with darkened margins. Lesions cross all veins.

Bleached stippling

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

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.

Poor leaf samples: Ozone injured leaf is exhibiting premature senescence and has lost most of its chlorophyll.

Good leaf samples

Ozone stipple

762

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.

large lesions with apparent fungal fruiting bodies visible under magnification

possible ozone stipple

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.

762This is not ozone injury.

Normal sized leaf sample

Undersized leaves are often found at the base of leaf branches in the inner crown.

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.

762

This is not ozone injury.

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

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.

365Dark pigmented stipple on the upper leaf surface of milkweed. The veins and veinlets remain green as do the leaf margins.

Ozone stipple

Close-up view of ozone stipple on green milkweed tissue.

Another good example of classic ozone stipple on common milkweed. The undersurface of this leaf is entirely green and free of any injury symptoms.

These tears in the leaf tissue are unrelated to ozone injury.

365

Ozone stipple

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.

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.

365

Ozone stipple

365This 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.

Ozone stipple on tall milkweed

Ozone stipple

Both Tall and Common Milkweed are bioindicator species. Use species code 365 for both.

365

The discoloration on the bottom leaf may be attributable to hot, dry weather. No ozone stipple is apparent.

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.

This is not ozone injury.

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.

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.

365

This is not ozone injury.

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.

365

This is not ozone injury.

365The 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.

blotchy red lesions

scattered small black spots

This is not ozone injury.

365With 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.

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.

WHITE ASH 541

White ash = buds are inset in the leaf scar.

Green ash = buds are set above the leaf scar.

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.

Dark brown lesion with a pale necrotic center - unrelated to ozone injury.

Ozone stipple

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.

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.

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.

541

Ozone stipple

541Darkened 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.

This is not ozone injury.

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.

541

This is not ozone injury.

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.

541Large 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

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.

541This 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

This is not ozone injury.

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

Leaf bronzing possibly due to exposure to hot, dry weather. The injury color and pattern are not typical of ozone injury.

541

This is not ozone injury.

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

DOGBANE 366

366Classic 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.

Light and scattered ozone stipple on the younger leaves

Note the more pronounced stippling on the older leaves. Veins remain green.

Ozone stipple

366

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

366The brown color of these necrotic areas are not typical of ozone injury.

The injury pattern (follows the leaf veins) and color of these lesions is not typical of ozone injury.

This is not ozone injury.

366

Clusters of necrotic lesions, especially along the leaf margin, are not typical of ozone injury.

This is not ozone injury.

366

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.

fungal-type lesions

This is not ozone injury.

ozone-like stipple

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.

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.

BIG LEAF ASTER 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.

Larger, brown lesions are unrelated to ozone injury.

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.

364

Ozone stipple

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.

364

These large dark lesions of unknown origin are bifacial and appear to cross the smaller veins of the leaf.

364This is not ozone injury.

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.

364

This is not ozone injury.

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.

SASSAFRAS 931

Classic ozone stipple on sassafras.

Note how the red-brown stipple is more pronounced on the older foliage.

Major leaf veins remain green.

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.

931leaf bronzing

Ozone stipple

Closer view of the bronze lesions characteristic of ozone injury on sassafras.

Larger zones of necrotic tissue are unrelated to ozone injury.

931

Ozone stipple

Pigmented ozone stipple on sassafras at a field site used for biomonitoring.

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.

Ozone stipple

931Leaf 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.

This is not ozone injury.

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.

SWEETGUM 611

Classic purple-red ozone stipple on sweetgum

Small pigmented stipplingoccurs 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 lesionswith lighter centers tend to sit on the leaf veins. Theyare unrelated to ozone injury.

611

Ozone stipple

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.

State: 3907365 County: 04

HexNum: 3008636 PlotNum: 1

Date: 8/19/03 Species: 611

Ozone stipple

The leaf undersurface is free of ozone injury.

Ozone-induced pigmented stipple on sweetgum. The larger, darker spots are not ozone injury.

611

Ozone stipple

611The 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

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.

611

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.

Ozone stipple

611This sample shows large blotches of discolored tissue.The lesions are bifacial and cross both large and smallveins. This injury pattern is not typical of ozone injury.

This is not ozone injury.

611This 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.

611With 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.

This is not ozone injury.

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 duck’s 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.

YELLOW POPLAR 621

Dark pigmented stipple on the upper leaf surface of yellow poplar at an ozone field site.

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.

Ozone stipple

621Classic 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 pressedproperly, or are otherwise difficult to read, cannot be validated for ozone injury.

Classic ozone stipple on yellow poplar

Ozone stipple

621Upper leaf surface ozone stipple. On pressed samples the stippling appears dark brown to red-black. Ozone stipple

621Severe ozone stipple is evident on this leaf sample. The injured areas are bounded by the smaller veins of the leaf.

Fungal-type lesionsare visible on this leaf sample. They areunrelated to ozone injury.

Ozone stipple

621

With a hand lens, classic pigmented stipple is readily visible on this leaf sample.

The large circular lesions are unrelated to ozone injury.

621

Scattered dark lesions are visible. They are large and bifacial. They are not typical of ozone stipple.

621The 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.

General discoloration due to improper voucher handling.

Large, bifacial lesions

This is not ozone injury.

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.

PIN CHERRY 761

Classic upper-leaf surface ozone stipple on pin cherry.761

Note: red stipple, green veins and margins.

Ozone stipple

761Classic pigmented stipple occurs between the veins onthe upper-leaf surface. Underside remains green.

Ozone stipple

761

Scattered ozone-like stippling

Necrotic areas of unknown origin.

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.

This is not ozone injury.

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 crewsinclude: 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@psu.edu and Art Chappelka at chappe@forestry.auburn.edu

Red maple (Acer rubrum)

Ozone stipple

Wild Plum (Prunus americana)

Nannyberry (Viburnum lentago)

Ozone stipple

Viburnum spp.

Tall Milkweed(Asclepias exalta)

Basswood (Tilia americana)

Ozone stipple

Wild grape (Vitis spp.)

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.

Ozone stipple

Sycamore (Platanus occidentalis)

Ozone stipple

Sourwood (Oxydendrum arboreum)

Ozone stipple

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

Blueberries Vaccinium spp.

Ironweed Veronia noveboracensis

Virginia creeper (Parthenocissus quinquefolia)

Ozone-like stipple on Robinia (locust) species.

Top: Two leaves of crown beard, smaller one with symptoms.

Bottom: Whole plant in natural stand; older leaves are symptomatic.

Possible ozone injury on crownbeard.

Ozone-like stipple on Silphium species.

Woodland Sunflower(Helianthus divaricatus)

Poison Ivy (Rhus radicans) Don’t take leaf samples from this plant!

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