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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
WILLOW:
| Clear to white oozing liquid exiting from the trunck and/or branches of the tree |
Bacterial Wetwood |
|
|