Woody Ornamentals

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Amsonia - rust Azalea - flower gall Birch - Septoria Birch - Cryptocline Boxwood - Pseudonectria canker Cherry - Phloeosporella Cherry - rust Cherry - Cercospora Clematis - Ascochyta Cotoneaster - Leaf spot Crabapple - C/apple rust Crabapple - Fire blight Crabapple - vole injury Dogwood - Septoria Elm - leaf spot Elm - black spot Elm - Dutch elm disease Forsythia - Phomopsis gall Forsythia - Sclerotinia Holly - Web blight Honeylocust - Cercospora Hydrangea - Cercospora LS Hydrangea - Xanthomonas Kerria - Phloeosporella Leucothoe - Leaf spot Maple - Anthracnose? Maple - Anthracnose Aureo. Maple - Discula? Maple - Verticillium wilt Maple - Monostichella Maple - Phyllosticta LS Mulberry - Phloeospora Nandina - vole injury Oak - Powdery mildew Oak - Marssonina Oak - rust Oak - Tubakia Oak - herbicide injury Paw Paw - Phyllosticta Paulownia - Phyllosticta Pear - herbicide injury Pecan - Botryosphaeria Photinia - Entomosporium Pine - sapsucker injury Planetree - Septoria Poplar - Septoria Privet - leaf spot Redbud - Downy mildew Redbud - Pseudocercospora Rose - Black spot Rose - Cercospora Spruce - Dothistroma Spruce - needle mold Spruce - Stigmina needle Spruce - Rhizosphaera Needlecast Taxus - Pestalotiopsis Walnut - White mold

Send comments and questions to Paul Bachi
Last Modified: 09-Oct-2012
Copyright © 2004, University of Kentucky, College of Agriculture, Department of
Plant Pathology

Plant: Amsonia (Amsonia sp.) (Apocynaceae) Back to List
Disease/Disorder: Leaf rust
Causal agent: Coleosporium sp.(fungus)
Signs: rust pustules with urediniospores on leaf surface
Symptoms: rust pustules on leaf surface.
Total image number: 6

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Plant: Azalea (Rhododendron sp.) (Ericaceae) Back to List
Disease/Disorder: Leaf and flower gall
Causal agent: Exobasidium vaccinii (fungus)
Signs: gall is fungal tissue
Symptoms: Leaf becomes galled tissue.
Total image number: 4

Plant: Birch (Betula sp.) (Betulaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Septoria betulae (fungus)
Signs: raised spore-producing bodies ("pycnidia") can be seen within spots.
Symptoms: Leaf spots can coalesce to form blighted areas.
Total image number: 4

Plant: Birch (Betula sp.) (Betulaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cryptocline betularum (fungus)
Signs: spore-producing bodies ("acervuli") can be seen within spots
Symptoms: Tan to gray spots on leaves.
Total image number: 6

Plant: Cotoneaster (Cotoneaster sp.) (Rosaceae) Back to List
Disease/Disorder: Phyllosticta leaf spot
Causal agent: Phyllosticta cotoneastri (fungus)
Signs: black spore-producing bodies ("pycnidia") can be seen within the brown spots on the leaves.
Symptoms: brown, ragged-edged spots on leaves.
Total image number: 8

Plant: Cherry (Prunus sp.) (Rosaseae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Phloeosporella padi (fungus)
Signs: Spore-producing bodies ("acervuli") may be swelled like a blister, sometimes not.
Symptoms: dark brown leaf spots with red border
Total image number: 8

Plant: Cherry (Prunus sp.) (Rosaseae) Back to List
Disease/Disorder: Rust
Causal agent: Tranzschelia sp. (fungus)
Signs: Pustules with spores ("urediniospores") [found on same leaf as with Phloeosporella padi above]
Symptoms: raised spots surrounded by light green/white leaf tissue
Total image number: 5

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Plant: Cherry (Prunus sp.) (Rosaseae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cercospora sp. (fungus)
Signs: Spore-producing hyphae ("conidiophores") grouped in clumps.
Symptoms: reddish-brown spots which can drop out and form shot-holes.
Total image number: 8

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Plant: Clematis (Clematis sp.) (Ranunculaceae) Back to List
Disease/Disorder: Leaf spot/blotch
Causal agent: Phoma or Ascochyta (fungus)
Signs: reddish-brown spore-producing bodies ("pycnidia") not well defined within spot/blotches.
Symptoms: brown to reddish-brown spots/blotches
Total image number: 7

Plant: Dogwood (Cornus florida) (Cornaceae) Back to List
Disease/Disorder: Septoria leaf spot
Causal agent: Septoria cornicola (fungus)
Signs: raised spore-producing bodies ("pycnidia") can be seen within spots.
Symptoms: darkened leaf spots
Total image number: 4

Plant: Elm (Ulmus carpinifolia 'Accolade') (Ulmaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: unknown (fungus) possibly Phyllosticta
Signs: spore-producing bodies ("pycnidia") can be seen within spots
Symptoms: Tan to gray spots on leaves.
Total image number: 4

Plant: Elm (Ulmus sp.) (Ulmaceae) Back to List
Disease/Disorder: Black spot
Causal agent: Stegophora ulmea (fungus)
Signs: raised spore-producing bodies ("acervulus") can be seen within spots.
Symptoms: small, raised black spots with a fine area of white tissue surrounding them, found mostly between the major veins of the leaves
Total image number: 4

Plant: Elm (Ulmus sp.) (Ulmaceae) Back to List
Disease/Disorder: Dutch elm disease (DED)
Causal agent: Ophiostoma ulmi (fungus)
Signs: Incubation of symptomatic pieces of elm branches, surface sterilized and placed in an incubation chamber produced the characteristic asexual stage or "synnemata" (conidiophores with clusters of colorless conidia) of the fungus.
Symptoms: Tree limbs will dieback and eventually the entire tree will die
Total image number: 9
Each of the last two rows of images is of a different sample.

Plant: Forsythia (Forsythia sp.) (Oleaceae) Back to List
Disease/Disorder: Twig dieback
Causal agent: Sclerotinia sp. (fungus)
Signs: hard, black survival structure called a “sclerotia” inside the stem
Symptoms: starts as a flower infection and work its way into the stem. On the stems, notice at the margin between healthy and diseased tissue you will see a copper/brown area on the stem. Within this area you can see a pattern of alternating lighter and darker copper/brown lines.
Total image number: 4

Plant: Apple, but can occur on Crabapple (Malus sp.) (Rosaceae) Back to List
Disease/Disorder: Fire blight.
Causal agent: Erwinia amylovora (bacterium)
Signs: May see droplets or oozings of bacteria from blighted tissue. Bacterial streaming from infected tissue.
Symptoms: Blighted shoot tips and/or flower blossom spurs.
Total image number: 4

Plant: Honeylocust (Gleditsia triacanthos var. inermis 'Skyline') (Fabaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cercospora sp. (fungus)
Signs: Spore-producing hyphae ("conidiophores") grouped in clumps.
Symptoms: brown spots with lighter center and darker brown boarder
Total image number: 7

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Plant: Hydrangea, Bigleaf (Hydrangea macrophylla) (Hydrangeaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cercospora sp. (fungus)
Signs: clumps of dark conidiophores and conidia (fine, silver threads) barely visible without magnification
Symptoms: spots with white to tan centers and a broad, dark boarder
Total image number: 15

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Plant: Hydrangea, Oakleaf (Hydrangea quercifolia) (Hydrangeaceae) Back to List
Disease/Disorder: spot/blotch
Causal agent: Xanthomonas sp. (bacterium)
Signs: none visible without dark-field magnification
Symptoms: reddish-brown spots and/or blotches on leaves.
Total image number: 4

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Plant: Kerria, Japanese (Kerria japonica) (Rosaceae) Back to List
Disease/Disorder: Leaf/twig blight
Causal agent: Blumeriella kerriae (teleomorph). Anamorph (Phloeosporella) seen in images below.
Signs: a ring of raised, spore-producing bodies ("acervuli") within spot.
Symptoms: On the leaves infection shows as reddish spots with dark borders and, if numerous, leaves yellow and fall. Stem cankers are produced as discolored more or less extended darkened areas which may crack open.
Total image number: 4

Plant: Leucothoe, drooping (Leucothoe fontanesiana) (Ericaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Phyllosticta sp.
Signs: black, spore-producing bodies ("conidia") within spot.
Symptoms: Brown spots with a darker color border. A bull's eye pattern can be seen in the larger spots.
Total image number: 9

Plant: Maple, 'Autumn Blaze' (Acer rubrum 'Autumn Blaze') (Aceraceae) Back to List
Disease/Disorder: Verticillium wilt
Causal agent: Verticillium spp. (fungus)
Signs:
Symptoms: Nursery trees shortly after transplanting showed poor growth. Sample of a darkened section of the vascular tissue of the stem below ground plated on a culture medium. After several days the fungal growth showed characteristic spore-producing structures for the fungus, Verticillium, species unknown.
Total image number: 9

Plant: Mulberry, weeping (Morus alba) (Moraceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Mycosphaerella mori (teleomorph). Anamorph (Phloeospora maculans) seen in images below (fungus).
Signs: a ring of raised, spore-producing bodies ("acervuli") within spot.
Symptoms: brown spots with slight yellow border on leaves.
Total image number: 9
Each row of images is of a different sample.

Plant: Paulownia (Paulownia tomemtosa) (Scrophulariaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Phyllosticta sp. (fungus).
Signs: raised, dark, spore-producing bodies ("pycnidia") can be seen within spots.
Symptoms: tan to gray spots on leaves.
Total image number: 4

Plant: Pear 'Bradford' (Pyrus calleryana 'Bradford') (Rosaseae) Back to List
Disease/Disorder: Herbicide injury
Causal agent: Triazine herbicide (likely)
Signs:
Symptoms: A yellow/light green coloration followed by browning and death of the tissue along the margins of the leaves. This distribution of symptoms is indicative of a chemical injury absorbed by the roots. Triazine herbicides and diphenylether herbicides cause these types of symptoms. “Pramitol" (`prometon'), which is commonly used under asphalt, can cause these symptoms and is a type of triazine herbicide.
Total image number: 4

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Plant: Pine (Pinus sp. ) (Pinnaceae) Back to List
Disease/Disorder: Sapsucker (woodpecker) injury
Causal agent: Sphyrapicus varius
Signs:
Symptoms: Looks like neatly arranged holes lined up in rows and columns. They can cause injury to trees but it generally not just to a single branch but rather the trunk and therefore a portion of the tree above the injury is affected. See the forest service publication from
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_sap/sap.htm
Total image number: 2

Plant: Planetree, London 'Bloodgood' (Platanus x acerfolia 'Bloodgood') (Platanaceae)
Back to List
Disease/Disorder: Leaf spot
Causal agent: Septoria platanifolia (fungus)
Signs: many small spore-producing bodies ("pycnidia") can be seen within the spots.
Symptoms: Dark brown leaf spots with surrounding yellow/brown areas.
Total image number: 7
Each row of images is of a different sample.

Plant: Poplar (Populus sp.) (Salicaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Septoria sp. (fungus)
Signs: spore-producing bodies ("pycnidia") can be seen within the spots.
Symptoms: dark brown spots
Total image number: 6

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Plant: Privet, Japanese (Ligustrum japonicum) (Oleaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: unknown (fungus)
Signs: dark spore-producing bodies ("pycnidia") can be seen within the spots.
Symptoms: Large brown spots with dark border and yellow margin
Total image number: 4

Plant: Oak, red oak group (Quercus sp.) (Fagaceae) Back to List
Disease/Disorder: Powdery mildew
Causal agent: Phyllactinia sp. (fungus)
Signs: white fungal growth sometimes with black dots which are the sexual reproductive bodies of the fungus called “cleistothecia”.
Symptoms: white growth sometimes with black dots. You can scrape portions of the mildew off the leaf to reveal the normal green color.
Total image number: 4

Plant: Oak, 2 species Back to List
(upper row of images Overcup or Bur, Quercus sp.;
lower row Chinquapin, Quercus prinoides) (Fagaceae)
Disease/Disorder: Marssonina leaf spot
Causal agent: Marssonina sp. (fungus)
Signs: one spore-producing body ("acervulus") can be seen within the spot usually centrally located.
The epidermal tissue splits open and an orange gelatinous mass of spores can be seen.
Symptoms: Gray/white to tan spots with thin brown border.
Total image number: 8
“Marssonina leaf spot” is common on poplar, birch, and bittersweet, but can also be seen on oak. It can cause defoliation of the tree.

Plant: Oak, red oak group (Quercus sp.) (Fagaceae) Back to List
Disease/Disorder: Rust
Causal agent: Likely either Pine-oak gall rust (also known as Eastern gall rust) caused by
Cronartium quercum f. sp. various or Fusiform rust caused by Cronartium quercum f. sp.
fusiforme
Signs: uredinia forming on bottom surface of leaves
Symptoms: leaves were distorted because of infections on major veins
Total image number: 4

Plant: Oak (Quercus sp.) (Fagaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Tubakia dryina (fungus)
Signs: raised, spore-producing bodies ("acervuli") within spot.
Symptoms: brown spots with dark spore-producing bodies
Total image number: 11 (top row from Post oak sample)
(bottom 2 rows from a Red oak sample)

Plant: Oak, Pin (Quercus palustris) (Fagaceae) Back to List
Disease/Disorder: Herbicide, possible growth regulator injury
Causal agent: unknown
Signs:
Symptoms: cupping, curling, elongated tips, scalloped and/or necrotic margins of leaves; new leaves necrotic
Total image number: 4

Plant: Photinia, red-tip (Photinia x fraseri) (Rosaseae) Back to List
Disease/Disorder: Entomosporium leaf spot
Causal agent: Entomosporium mespili (fungus)
Signs: raised, spore-producing body ("acervuli") within spot. Spores look like an insect.
Symptoms: Tan spots with dark border and usually a single spore-producing body in the center.
Total image number: 5

Plant: Redbud (Cercis canadensis) (Fabaceae) Back to List
Disease/Disorder: Leaf blight, also called Isariopsis leaf spot
[Note: The top row of images also contain symptoms of the disease Downy mildew.]
Causal agent: Pseudocercospora vitis (fungus)
Signs: spore-producing bodies ("synnemata") can be seen within leaf spots.
For micrographs of synnemata and spores see
http://www.ca.uky.edu/agcollege/plantpathology/ext_files/DiagnosticImagesSmallFruit.htm#GrapeLB

Symptoms: Purple black leaf spots with yellow halo less obvious on the underside of the leaf.
Total image number: 9

Plant: Redbud (Cercis canadensis) (Fabaceae) Back to List
Disease/Disorder: Downy mildew
[Note: The first two images also contain symptoms of Pseudocercospora leaf blight.]
Causal agent: Plasmopara cercidis (fungus)
Signs: White to tan to brown sporangiaphores with sporangia seen within the blocky areas on the underside of the leaves.
Symptoms: Necrotic tissue seen in blocks on the upper side of the leaves. White to tan to brown fluffy material seen on the underside of the leaves opposite the necrotic tissue on the upperside.
Total image number: 7

Plant: Rose, yellow tea (Rosa x odorata) (Rosaceae) Back to List
Disease/Disorder: Black spot
Causal agent: Diplocarpon rosae (fungus) (Marssonina rosae [imperfect shown])
Signs: raised, spore-producing body ("acervulus") within spot. Two-celled spores (conidia).
Symptoms: Feathery purple/black spots with no definite margin.
3rd row of images, shows unidentified rose leaves with more classic symptoms of Black spot.
4th row of images, shows a case of early season, severe infection without classic black spots.
5th row of images, shows very small infected leaf with spore-producing bodies and spores
Total image number: 15

Plant: Rose, Knockout (Rosa x) (Rosaceae) Back to List
Disease/Disorder: Cercospora leaf spot
Causal agent: Cercospora rosicola (fungus)
Signs: Dark, fuzzy spores (conidia) and conidiophores in the center of the brown spots.
Symptoms: Brown spots with darker border.
Total image number: 6

Plant: Spruce (Picea sp.) (Pinaceae) Back to List
Disease/Disorder: Dothistroma needle blight
Causal agent: Dothistroma septosporum (syn. pini) (fungus)
Signs: black, spore-producing bodies ("acervuli") breaking through needle surface.
Symptoms: Tan areas with dark border and/or dead tips with dark border between dead and healthy portion of the needle.
Total image number: 4

Plant: Spruce, Colorado (Picea pungens) (Pinaceae) Back to List
Disease/Disorder: Stigmina needle blight
Causal agent: Stigmina sp. (fungus)
Signs: Fuzzy, black tufts rising from stomata on needles; not as well defined as with Rhizosphaera.
Symptoms: Off-colored needles usually older than the current year's needles.
Note: close-up of needles also show characteristic yellow flecking of mite injury.
Total image number: 10

Plant: Spruce, Norway (Picea abies) (Pinaceae) Back to List
Disease/Disorder: Rhizosphaera needlecast
Causal agent: Rhizosphaera kalkoffii (fungus)
Signs: Discrete, dark brown to black pycnidia rising from stomata on needles; much more sharply defined than with Stigmina.
Symptoms: Off-colored needles usually older than the current year's needles.
Total image number: 10

Plant: Taxus (Taxus sp.) Back to List
Disease/Disorder: saprophytic fungus on dead needles
Causal agent: Pestalotiopsis sp. (fungus)
Signs: black spore-producing bodies ("acervuli") in dead areas of needles.
Symptoms: dead needles or dead tips of needles.
Total image number: 4
It is common on plant tissue that has been subject to freeze injury or sunscald.

Plant: Willow, corkscrew (Salix matsudana 'Tortuosa') (Salicaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cercospora sp. (fungus)
Signs: small dark spore-producing bodies ("conidiophores") and fine silvery threads which are the spores can be seen within the spots.
Symptoms: dark brown spots with darker border
Total image number: 4