Apple (Malus)

Chlorosis: Pale green to yellowish leaves

Fire Blight: Light brown to black leaves; dried fruit; water logged blossoms; dead 'shepherds crook' twigs and branches

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Powdery Mildew: White powder-like substance on the upper and lower areas of the leaf

Ash (Fraxinus)

Ash Flower Gall Mite: Infested flowers become deformed and remain on trees as green masses until fall

Emerald Ash Borer: Adult is 1/2 inch long, narrow, metallic green beetle, D shaped exit hole (1/8" diameter) found on trunk or branches *this insect has not been officially detected in Wyoming*

Leafcurl Ash Aphid: Leaves tightly rolled and thickened; white/waxy insects may be evident

Lilac/Ash Borer: Exit holes the size of a pencil eraser; usually found along branch crotches, branches, or the main stem; die-back may be evident

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Wood Boring Insects of Ash Trees: Major and minor wood boring insects of ash trees.

Aspen (Populus)

Aphids: Leaf curling, presence of ants or a sticky honeydew-like substance on the leaf

Bacterial Wetwood: Oozing liquid from wounds; yellow-brown discoloration of bark

Chlorosis: Pale green to yellowish leaves

Cytospora Canker: Orange oozing spores form along the main stems; girdling occurs on section of tree above the canker

Leaf Spots: Tan to black spots that develop on the leaf surface

Poplar Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Poplar Twiggall Fly: Presence of smooth, knot-like gall on tip of aspen twig; Cytospora Canker may develop around the gall

Powdery Mildew: White powder-like substance on the upper and lower areas of the leaf

Shoot Blight: Irregular brown/black spots form on leaf; infected shoots turn black and resemble a 'shepherd's crook'

Birch (Betula)

Bronze Birch Borer: Bronze colored insect borer; D-shaped exit holes along main stem and branches; Dieback of terminal branches

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Black Locust (Robinia)

Locust Borer: Insect is an inch long and very colorful (black body, yellow stripes, red legs); Dieback and knotty swelling may be evident

Boxelder (Acer negundo)

Aphids: Insects sucking on leaf surface, sticky leaf surface, flying insects around the canopy

Boxelder Bugs: Black 1/2" insects with red lines on thorax, orange/red eggs in clusters on leaf surface, usually found surrounding homes near south-facing windows

Buckeye/Horsechestnut (Aesculus)

Leaf Scorch: Burn appearance along margin of the leaf; can resemble leaf spots

Catalpa (Catalpa)

Verticillium Wilt: Rapid dieback or wilting of individual branches on tree; usually not the entire tree

Cherry (Prunus)

Aphids: Leaf curling, presence of ants or a sticky honeydew-like substance on the leaf

Cytospora Canker: Orange oozing spores form along the main stems; girdling occurs on section of tree above the canker

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Peachtree Borer: Presence of a wet spot or oozing, gummy sap along lower trunk

Chokecherry (Prunus)

Black Knot Disease: Black, swollen growths form along the branches and stems; galls may be covered with olive-green spores

Eastern Tent Caterpillar: White webbing present is thickly constructed in the forks and crotches of trees; the larvae do not feed within their webs, but congregate there at night and during rainy weather.

Eriophyid Mites: Leaves have finger-like protrusions growing on surface.

Fall Webworm: White webbing present in the branches and crown of the tree, and occur in summer and fall, whereas eastern tent caterpillars appear in spring.

Cottonwood/Poplar (Populus)

Bacterial Wetwood: Oozing liquid from wounds; yellow-brown discoloration of bark

Cytospora Canker: Orange oozing spores form along the main stems; girdling occurs on section of tree above the canker

Leaf Spots: Tan to black spots that develop on the leaf surface

Petiole-Gall Aphid: Swelling/thickening of the petiole which results in the formation of round galls

Poplar Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Powdery Mildew: White powder-like substance on the upper and lower areas of the leaf

Shoot Blight: Irregular brown/black spots form on leaf; infected shoots turn black and resemble a 'shepherds crook'

Crabapple (Malus)

Fire Blight: Light brown to black leaves; dried fruit; water logged blossoms; dead 'shepherds' crook' twigs and branches

Chlorosis: Pale green to yellowish leaves

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Powdery Mildew: White powder-like substance on the upper and lower areas of the leaf

Elm (Ulmus)

Bacterial Wetwood: Oozing liquid from wounds; yellow-brown discoloration of bark

Elm Leaf Beetle: Leaves are skeletonized; holes throughout leaves

Elm Leafminer: Tunnels made throughout the leaf surface

European Elm Scale: Scales group together on crotch of branches; scales are dark-red, purple, or brown surrounded by white wax fringe

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Squirrel Damage: Squirrels tend to chew on buds and tree bark during winter months; may cause girdling around wounds

Hackberry (Celtis)

Eriophyid Mites: Branches/twigs deformed into a dense mass called "Witches Broom"

Hackberry Nipplegall: Leaves with large, raised bumps

Hawthorn (Crataegus)

Chlorosis: Pale green to yellowish leaves

Fire Blight: Light brown to black leaves; dried fruit; water logged blossoms; dead 'shepherds crook' twigs and branches

Pear Slug: Chewing/holes in leaves

Rusts: Orange/yellow spots on leaf surfaces

Honeylocust (Gleditsia)

Honeylocust Leafhopper: Spotty yellow foliage; can occur alongside Plant Bug infestation in late spring

Honeylocust Plant Bug: Dieback/twisted leaves; usually occurs on new growth

Honeylocust Podgall Midge: Leaflets swell to form galls; When maggots emerge, galls drop leaving bare branches

Honeylocust Spider Mite: Orange 1 mm mites usually found under bud scales/in bark cracks; Bronze dieback within foliage

Thyronectria Canker: Rust to Black colored fruiting bodies along dead areas of bark; Premature leaf drop

Juniper (Juniperus)

Cedar Apple Rust: Large galls develop on ends of branches; orange telial thorns form during rainy weather; dieback throughout tree

Juniper Spittlebug: White, frothy masses develop on needles

Spider Mites: Speckled leaf surface; plant appearance becomes bronze/gray; leaf scorch

Linden/Basswood (Tilia)

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen. Primarily littleleaf lindens are of concern.

Leaf Scorch: Leaf spots; burn along margin of the leaf

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Maple (Acer)

Aphids: Leaf curling, presence of ants or a sticky honeydew-like substance on the leaf

Chlorosis: Pale green to yellowish leaves

Eriophyid Mites: Leaves display masses of pinkish patches

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Winter Sunscald: Sunken/discolored bark; cracked or sloughed off bark

Mountainash (Sorbus)

Fire Blight: Light brown to black leaves; dried fruit; water logged blossoms; dead 'shepherds crook' twigs and branches

Japanese Beetle: Brown to bronze and metallic green beetle with six white tufts of hair along hind sides of abdomen.

Oystershell Scale: A cluster of grey scales resembling rice along the bark and branches; sometimes settling near buds

Oak (Quercus)

Bullet Gall: Woody, round gall on branches

Chlorosis: Pale green to yellowish leaves

Squirrel Damage: Squirrels tend to chew on buds and tree bark during winter months; may cause girdling around wounds

Pine (Pinus)

Chlorosis: Pale green to yellowish needles

Diplodia Blight: Needle kill at tips of branches; needles yellow/brown in color

Dothistroma Blight: Needle drop/browning of needles; bare branches

Ips Beetle: Tunnels underneath bark; severe dieback present

Mountain Pine Beetle: Popcorn-like "pitch tubes" of resin along main trunk; flakes of bark lie on ground below tree canopy; yellow/red foliage

Pine Wilt Disease/Nematode: Primarily seen in exotic species, quick fading of color in leaves/needles within a few weeks to a couple of months leading to mortality of the tree.

Spruce (Picea)

Cytospora Canker: Orange oozing spores form along the main stems; girdling occurs on section of tree above the canker

Ips Beetle: Tunnels underneath bark; severe dieback present typically from the top of the tree downward.

Rhizosphaera Needle Cast: Loss of needles on innermost branches towards the bottom of the spruce; black spots on surface of needle

Spider Mites: Speckled leaf surface; plant appearance becomes bronze/gray; leaf scorch

Walnut (Juglans)

Thousand Cankers Disease: Yellowing and wilting leaves on single branches

Willow (Salix)

Bacterial Wetwood: Oozing liquid from wounds; yellow-brown discoloration of bark

Cytospora Canker: Orange oozing spores form along the main stems; girdling occurs on section of tree above the canker