City Of Greeley
 

Forestry eConsult

This list includes common issues or problems observed that affect certain tree species found in Greeley. After the description, you will find the probable cause. The link will take you to a document which explains in detail the problem, its effects, cure or treatment, and other resource information. If you do not find the information you are looking for, feel free to contact us via e-mail or phone. Thank you!

APPLE:

ISSUES OR PROBLEMS OBSERVED

PROBABLE CAUSE

White powdery material on upper or lower surface of leaf Powdery Mildew
Pale green or yellowish leaves Chlorosis
Darkened spots or lesions on upper leaf surface or sometimes on fruit Apple Scab
Blackened or wilted leaves, usually at the tips of branches OR discoloration of twigs or branches, usually at the tips OR wilting or browning of blossoms OR shriveling or dried fruit Fire Blight
Tunneling or wormy fruit Codling Moth
ASH:

ISSUES OR PROBLEMS OBSERVED

PROBABLE CAUSE

Distortion of leaves OR pinhole wounds on leaves OR feeding on leaves when mostly primary veins remain Brownheaded Ash Sawfly
Leaves tightly rolled and thickened, masses of sticky white waxy covered insects Leafcurl Ash Aphid
Smooth semicircular cuts made on leaf edge Leafcutter Bees
White powdery material on upper or lower surface of leaf Powdery Mildew
Pencil eraser-sized holes in stem, branch or branch crotches. These wounds sometimes are seen with insect skeletons protruding from them. Sometimes visible dieback of individual limbs in tree canopy or dieback of entire canopy. Lilac/Ash Borer
Distortion of flowers or woody-like masses or growths, mostly at tips of twigs or along twig Ash Flower Gall Mite
ASPEN:

ISSUES OR PROBLEMS OBSERVED

PROBABLE CAUSE

Young leaves or small twigs blackened, mostly starting at the new shoot Shoot Blight
Dark round spots on leaves Ink Spot
Black spots on leaves with yellowish margins Marssonina Blight
Sucking insects on leaves; leaves are sticky and have a spotty glossy appearance Aphids
White powdery material on upper or lower surface of leaf Powdery Mildew
Pale green or yellowish leaves Chlorosis
Round swellings on twigs in various sizes and sometimes on main branches or stems Poplar Twiggall Fly
Grayish or blackened colored scales, sometimes resembling sections of rice along mostly main stems and sometimes along branches and twigs Oystershell Scale
Small branches or twigs with pimple-like fruiting bodies on the bark, usually on main stems or larger branches OR sunken discolored areas, sometimes with elongated or visible oozing noticeable Cytospora Canker
Oozing liquid from wounds, sometimes white or frothy Bacterial Wetwood
Color photos of common Aspen problems What's Ailing Your Aspen? Poster
BOXELDER:
Insect sucking on leaves, sticky substance on leaves and flying insects around canopy Aphids
Masses of reddish eggs on leaves OR sometimes noticeable feeding on seeds OR 1/2 long bugs, mostly black with reddish lines and reddish abdomen, sometimes congregating in homes near windows Boxelder Bugs
CATALPA:
Wilting or die-back of individual branches in tree, usually not entire tree Verticillium Wilt
CHERRY:
Puncture wounds in fruit Cherry Curculio
Visible insect boring into tree, usually at or below soil line OR noticeable die-back in canopy of tree OR tree mostly looks stressed Peach Tree Borer
Discoloration of bark OR sometimes pimple-like fruiting bodies near discolored areas on bark and sometimes oozing OR amber or dark reddish colored gum-like substance oozing from stem Cytospora Canker
Insects on leaf surface and sometimes noticeably sticky residue on leaves Aphids
CHOKECHERRY:
Webbing formed around branches in canopy of tree Fall Webworm
COTTONWOOD:

ISSUES OR PROBLEMS OBSERVED

PROBABLE CAUSE

Webbing formed around branches in canopy of tree Fall Webworm
Young leaves or small twigs blackened, mostly starting at the new shoot Shoot Blight
Black spots on leaves with yellowish margins Marssonina Blight
Lesions or black specks which can enlarge and form larger blotches of dead material on the leaf OR sometimes pimple-like fruiting bodies appear on the leaf surface Septoria Leaf Spot
Dark round spots on leaves Ink Spot
White powdery material on upper or lower surface of leaf Powdery Mildew
Swelling in leaf veins or leaf stems and sometimes hollow swellings on new growth Petiole-Gall Aphid
Oozing of liquid from trunk, often from wounds or branch crotches Bacterial Wetwood
CRABAPPLE:

ISSUES OR PROBLEMS OBSERVED

PROBABLE CAUSE

Darkened spots or lesions on upper leaf surface Apple Scab
White powdery material on upper or lower surface of leaf Powdery Mildew
Blackened or wilted leaves, usually at the tips of branches OR discoloration of twigs or branches, usually at the tips OR wilting or browning of blossoms OR shriveling or dried fruit Fire Blight
Pale green or yellowish leaves Chlorosis
ELM:
Leaves skeletonized and holes chewed in leaves Elm Leaf Beetle
Leaves tunneled or leaves mined inside leaf surface Elm Leaf Miner
Leaves chewed through the entire leaf, sometimes in a shotgun pattern; some leafmining may be visible Elm Flea Weevil
Insect scales that attach themselves to mostly branches and smaller twigs; when hands are rubbed over top of them, they appear bloody, sometimes accompanied by a black mold that covers the area the scale infected AND sometimes is indicated by yellow leaves on individual branches in the canopy European Elm Scale
Smaller branches and twigs have bark missing in large sections Squirrel Girdling
Oozing of liquid from trunk, often from wounds or branch crotches; will often appear grayish in color on elms Bacterial Wetwood
HACKBERRY:
Leaves with large raised bumps or nodules Hackberry Nipplegall
Twigs or branches deformed in to a dense mass of twigs often called a "witches broom" Eriophyid Mites
HAWTHORN:
Blackened or wilted leaves, usually at the tips of branches OR discoloration of twigs or branches, usually at the tips OR wilting or browning of blossoms OR shriveling or dried fruit Fire Blight
Pale green or yellowish leaves Chlorosis
Chewing or skeletonizing of leaves Pear Slug
Orange-yellow lesions on leaf surfaces and sometimes small light-colored projections on the underside of the lesion Rusts
HONEYLOCUST:
Shortly after leaf emergence, new leaves are killed and older leaves may be distorted and discolored OR overall growth and canopy appears stunted Honeylocust Plant Bug
Tree appears thin, usually seen with small pod or gall-like formations, typically best seen at the tips of branches Honeylocust Podgall Midge
Small and slight flecking of foliage is visible, occasionally accompanied by sticky substance Honeylocust Leafhopper
Leaves discolor and turn orangish later in the summer and can prematurely drop Honeylocust Spider Mite
Smaller branches and twigs have bark missing in large sections, but usually smaller sections of bark are noticed to be damaged in the first several branch crotches Squirrel Damage
Small branches or twigs with pimple-like fruiting bodies on the bark OR on main stems or larger branches OR sunken discolored areas and sometimes elongated or visible oozing is noticeable Cytospora Canker
Premature leaf drop and irregular shaped brown to black fruiting bodies on twigs, larger branches or stem Thyronectria Canker
JUNIPER:
Frothy masses on needles Juniper Spittlebug
Needles bleached or brown Winter Desiccation
Pruning Damage
Vole Damage
Needles become discolored, usually with small flecks visible Spider Mite
Galls or gelatinous tissue formations on branches Juniper Rusts
LINDEN:
Small branches or twigs with pimple-like fruiting bodies on the bark OR on main stems or larger branches OR sunken discolored areas and sometimes elongated or visible oozing is noticeable Cytospora Canker
MAPLE:
Pale green or yellowish leaves, particularly on Silver, Red, or Autumn Blaze Maples Chlorosis
Insects sucking on leaves, often associated with sticky substance on leaves Aphids
Large dead and discolored areas, usually on south to southwest side of trunk Winter Sunscald
MOUNTAIN ASH:
Blackened or wilted leaves, usually at the tips of branches OR discoloration of twigs or branches, usually at the tips OR wilting or browning of blossoms OR shriveling or dried fruit Fire Blight
OAK:
Pale green or yellowish leaves Chlorosis
PEACH:
Burrowing into the trunk at or below surface line OR clear gum oozing from trunk, almost always at or near ground line Peach Tree Borer
Discoloration of bark OR sometimes pimple-like fruiting bodies near discolored areas on bark and sometimes oozing OR amber or dark reddish colored gum-like substance oozing from stem Cytospora Canker
PEAR:
Skeletonizing or chewing of leaves Pear Slug
Blackened or wilted leaves, usually at the tips of branches OR discoloration of twigs or branches, usually at the tips OR wilting or browning of blossoms OR shriveling or dried fruit Fire Blight
Pale green or yellowish leaves Chlorosis
PINES:
Whole Tree is faded out OR bubble gum-looking residues are being pushed out from the trunk, primarily on Ponderosa, Scots or Pinyon Mountain Pine Beetle
On Pinyon, oozing pink or yellow pitch masses from the trunk Pinyon Pitch Mass Borer
On Austrian, oozing popcorn-like masses or pitch, usually in the tops of the tree and usually near crotches Zimmerman Pine Moth
SPRUCE:
Ends of twigs and small branches have distorted growth and/or dieback from what appears to be a seed cone Cooley Spruce Gall Adelgid
SYCAMORE:
Tree doesn't leaf out until late May or early June, leaves with blackened spotting OR witches broom with small dead branches Anthracnose
WALNUT:
Yellowing and thinning of the upper crown, wilting of foliage Thousand Cankers Disease
WILLOW:
Clear to white oozing liquid exiting from the trunck and/or branches of the tree Bacterial Wetwood