Forestry

There are so many conditions that affect our landscapes. High winds, cold temperatures, high soil pH, low precipitation levels and heavy clay soils are just some of the factors that work against our landscapes.

1. The planting hole should be 2 times the size of the root ball and never deeper than the bottom of the root ball. Loosen or scarify the soil on the sides of the planting hole; this helps the roots establish more rapidly.
    
2. Be very gentle when handling any root ball. If a plant is planted from a container, gently remove the container and tease or loosen any spiraling roots. If the tree is a balled-and-burlapped tree; place the tree next to the hole and remove the bottom 1/3 of the wire basket, set the tree in the hole gently, fill hole approximately halfway with soil, then remove the upper 2/3 of the wire basket.
    
3. Backfill with existing soil and gently pack the soil. Do not compact the soil which will make water penetration difficult. If amending soil with organic material, never use more than 1/3 organic matter to existing soil.
    
4. Build a water retention ring with the remaining soil and fill this ring with water. Proper watering is critical to a tree’s survival. Check with your local nursery for the watering needs of specific trees.
    
5. Apply mulch to the inside of this ring, never more than 3" thick. The mulch will help to reduce the weed population, keep lawn mowers and weed eaters away from bark and help the tree maintain moisture levels.
    
6. Due to Greeley’s high winds, it helps to stake and guy a tree for its first year or two of establishment. It is recommended to use nylon straps, always allow for growth of the tree and never put constricting wires in contact with the bark of the tree.
    
7. Prune only what is needed; remove crossing branches and double leaders only. After several years of establishment, pruning is usually required.
    
8. Before selecting a tree, look at the site where you will be planting. Decide about size, shape and other features (color, flower, fruit, drought-tolerance, etc.) that you want in a tree.

Planting in the City right of way: ​

Landscaping on public right-of-way is a privilege extended to Greeley residents by the City; however, that privilege carries with it the responsibility to obtain the proper planting permit and adherence to City of Greeley planting standards. Any tree(s) planted on public rights-of-way must be preceded with a landscape permit issued by the Community Development Department. Permit information is available on our planting permit page.

Failure to obtain a permit prior to installation of the landscape will result in a fine twice the amount of the permit. ​

For pruning diagrams and to view technical fact sheets on pruning, visit Colorado State University. For interactive and fun pruning instructions and video, visit The National Arbor Day Foundation, and launch the pruning program.

1. Training a tree by properly pruning it when it is young will minimize future maintenance problems. Also, pruning will create a better-formed and healthier tree.
    
2. Be sure to remove all dead, diseased and broken branches. The remaining branches will become healthier and better able to withstand heavy snow buildup.
    
3. When pruning larger branches, first make an undercut about six inches from the main branch. Cut it off from the top down, and then remove the stub at the branch collar. This method prevents stripping of the bark.
    
4. Never leave a stub; it will never callous and can become an entry point for decay-causing organisms. Proper cuts will callous properly. Do not apply tree wound paint. Research reveals that trees callous faster and are less susceptible to infection when no wound dressings are applied.
    
5. It is also important not to make flush cuts that wound the tree. Use a professional, licensed tree service when the job is beyond your ability or skill.
    
6. All tree service firms working in Greeley must be licensed and insured. Use only licensed tree service firms.
    
7. Remember, Never Top Trees! Topping is an unacceptable method of pruning which increases a tree’s maintenance needs and creates very weak and hazardous branches.

1. On a new tree, create a basin or "tree well" around the base of the tree. A young tree requires a basin just outside the root ball. Water the tree slowly. Let the water run at a trickle into the basin and soak the soil. You cannot water trees too much at one time; however, you can water too often. Generally, it is best to water newly-planted trees at least weekly for the first month and once every two or three weeks for the remainder of the year. All trees take special care in watering the first 2-3 years to become established. Don't forget to winter water ALL trees.
    
2. Once trees become established, water according to the requirements of the tree. Some trees grow better in drier sites and some in moist sites. Consult the Trees for Greeley page to help determine the watering needs of your tree(s). Also, contact the Greeley Water Department for information on "Xeriscape" (lower water need) landscaping.
    
3. Your soil texture will determine the watering interval. In this area, the soil texture ranges from heavy clay to sand. In heavy clay, watering may be done less often, but run-off problems may require watering in two half-hour periods in order to achieve the suggested soaking. Sandy soils, on the other hand, will dry out more quickly requiring you to water more often.
    
4. When the nights turn cool and the days shorten, it is best to reduce watering trees and other plants. Labor Day is a good reference point. This is the time when plants prepare for winter through a process referred to as "hardening off."
    
5. Watering and fertilizing encourage continued growth, and trees cannot accomplish their natural anti-freeze preparation before frost begins. This can cause winter kill. Generally, it is best to water once a month in the winter and only after trees have hardened off.
    
6. Keep in mind that wind, temperature, exposure and drainage also influence watering needs.
    
7. Always allow for lawn irrigation and natural watering by rain or snowfall, and adjust your watering schedule accordingly.
    
8. Now available is detailed information on watering trees from Denver Water.

There are any number of things that can affect plant health.

• Trees do not, as a rule, require fertilizer. In most cases adequate nutrients are available from the existing soil and lawn fertilization that regularly occurs.
• If there is a nutrient deficiency and supplemental fertilization is recommended, the ideal time to fertilize trees is after they leaf out in the spring.
• A common nutrient problem in Colorado is the availability of iron, manganese and other micro-nutrients to trees because of high pH soils, (pH is an index of acidity-alkalinity). A lack of micro-nutrients can cause a yellowing or chlorosis of the leaves, especially in some Oaks, Silver Maples, and Cottonwoods.
• Always consult with a professional arborist or Colorado State University Cooperative Extension office to get an accurate diagnosis of the problem.

Requests are received from citizens to inspect trees or shrubs on their property. A staff arborist then visits the site and advice is given concerning potential insect, disease, structural and/or cultural problems. Recommendations are then made toward corrective actions that should be taken to alleviate or prevent particular problems.

Every effort is made to provide advice or information by phone, mail or email at no charge. On-site consultations will be arranged around other duties, typically at no charge. Consultations may be performed by any of the qualified full-time staff, keeping in mind that it is very difficult for us to schedule appointments.

To learn more about the following problems, visit the Colorado State University Cooperative Extension Site.

Common Diseases In Greeley

Fireblight - Crabapples, Hawthorns, Mountain Ash, Apples, Pears
Cytospora Canker - Aspen, Cottonwood, Poplars, Apple, Cherry, Honeylocust, Peach, Plums, Birch, Willow, Siberian Elm, Spruce, Silver Maple, Mountain Ash
Thyronectria Canker - Honeylocust
Dutch Elm Disease - American and English Elms
Chlorosis - Aspen, Silver Maple, Austrian Pine, Crabapple, Red Oak, Pin Oak
Bacterial Wetwood - Wide range of trees.
Pine Wilt - Scots Pine
Thousand Cankers Disease - Walnuts

Many insects attack trees in only a secondary capacity. In other words, they are there because the plant has already been predisposed to a particular problem and is under a great amount of stress.

Two of Greeley's major insect pests, the European Elm Bark Beetle and the Spruce Ips Engraver Beetle, both attack trees under stress. The Elm Bark Beetle transmits Dutch Elm Disease and the Ips Beetle destroys Spruce. Just as preventative maintenance works with automobiles, plants free from insects and disease work the same way. Pay attention to proper watering practices, planting and pruning techniques, fertilization, and sound tree selection/placement.

For more information or to help diagnose your own insect problem, visit the Colorado State University Cooperative Extension Site.

Common Insects In Greeley

• Aphids - Wide range of plants
• Elm Leaf Beetle - Elms
• Elm Flea Weevil - Elms
• Elm Bark Beetle - Elms
• Elm Leaf Miner - Elms
• Cooley Spruce Gall - Spruce
• Ips Engraver Beetle - Spruce
• Boxelder Bug - Boxelders
• Hackberry Nipple Gall - Hackberry
• Spider Mites - Spruce, Honeylocust
• Poplar Twiggall - Aspen
• Scale - Aspen, Elms
• Pinyon Pitch Mass Borer - Pinyon Pine
• Zimmerman Pine Moth - Austrian Pine
• Lilac/Ash Borer - Lilac, Ash
• Cynipid Wasp - Bur Oak
• Mountain Pine Beetle - Scots Pine, Ponderosa Pine, Pinyon Pine, Bristelcone Pine, Lodgepole Pine
• Pine Wilt Nematode and Pine Sawyer Beetle - Scots Pine

• Trees, like other plants, are subject to insect infestations, which may endanger their well-being. If insects are at damaging levels, properly-timed spraying or soil injected pesticides are needed to control these infestations.
• The decision to use pesticides should be made only after careful consideration. In many cases, undesirable insects are already being controlled by natural enemies or weather conditions and/or the health of the tree is not being affected.
• Some situations may require pest control but before this is done, have a proper diagnosis of the problem. Know the pest name, plant name and the product recommended for best control. Blanket spraying of entire yards is a poor practice. Also, non-chemical methods of control should be considered first.
• A pesticide used for insects in trees and shrubs must be labeled for the target pest and/or the tree it’s on. Read the label completely before using any pesticide.
• Use only competent pesticide application companies licensed by the Colorado Department of Agriculture. They have the equipment to insure an adequate dosage, application and coverage.

There is a difference between environmental and mechanical damage. However, understanding these important and basic tips can help you maintain control over these issues.

Sunscald

Sunscald happens during cold, bright days in winter. Young, thin-barked trees are most susceptible. During warm winter days, cells and tissues become activated. When freezing temperatures develop overnight, those cells freeze. Sunscald can be prevented. We recommend the use of commercial tree wraps, which are available at most garden centers and plant nurseries. Wrap trees from October through April. Begin at the base of the trunk and overlap wrap spiraling upward; secure at the first branch union with masking tape. Wrap trees at least the first two years after planting or transplanting. DO NOT leave wrap on all year round. This will restrict tree growth and increases chances for attack from disease and insects.

Drought/Overwatering Injuries

All plants can be injured by receiving too much water just the same as if they do not receive enough. Most insects and disease will not infest healthy trees. By not having the proper watering schedules for your particular landscape, your plants are susceptible to attacks from insects and disease. Basically, proper watering helps keep the plant's immune system working properly. If planning a new landscape or working with a fairly young landscape, utilize all resources available to discover what watering requirements are necessary for each plant. Mature landscapes offer little opportunity to re-design watering zones or schedules. Talk to a professional about making watering changes. Once a landscape adapts to a particular schedule, stress may be induced if that schedule is changed. Remember, ALWAYS water the ENTIRE year. During warm dry spells in the winter, drag out your hose and give your landscape a good soaking.

Frost Damage

Frost damage occurs with both early Fall frosts OR late Spring freezes. Avoid heavy nitrogen applications to your landscapes after July. This will help your plants to begin dormancy and will not encourage new growth at an inappropriate time. Spring freezes typically cause more noticeable damage than fall. This is a time of strong growth. Frost injuries can be difficult to prevent; however, ideally you should plan to use plants that fit our climate and hardiness zone. Be wary when using tender plants; they will need proper protection according to their growth habits and requirements. Each plant has its own micro-climate in which it will perform better.

Weedeater/Lawnmower Damage

This damage is easily prevented. Ideally, you need to maintain a "tree ring" around the base of each tree. You can do so effectively with herbicide (weed and grass) destroying chemicals. Carefully prune all basal sprouts and suckers off of the tree before applying chemicals. Providing this ring around trees helps to eliminate the need for weedeaters and lawnmowers to get too close to the base of the tree, doing fatal damage. Also, shrubs and shrub beds should be isolated from turfed areas. Do so with edging materials of your choice, and place a wood chip mulch inside your shrub bed.

Herbicide Damage

This damage occurs from the improper use of chemical weed and pest controls. Diagnosis of the problem is not always simple. A complete history of maintenance practices and technical information is needed to properly diagnose the problem

• Powdery Mildew: White powdery material on upper or lower surface of leaf
• Chlorosis: Pale green or yellowish leaves
• Apple Scab: Darkened spots or lesions on upper leaf surface or sometimes on fruit
• Fire Blight: 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
• Codling Moth: Tunneling or wormy fruit

• Brownheaded Ash Sawfly: Brownheaded Ash Sawfly: Distortion of leaves or pinhole wounds on leaves or feeding on leaves when mostly primary veins remain
• Leafcurl Ash Aphid: Leaves tightly rolled and thickened, masses of sticky white waxy covered insects
• Leafcutter Bees: Smooth semicircular cuts made on leaf edge
• Powdery Mildew: White powdery material on upper or lower surface of leaf
• Lilac / Ash Borer: 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.
• Ash Flower Gall Mite: Distortion of flowers or woody-like masses or growths, mostly at tips of twigs or along twig

• Shoot blight: Young leaves or small twigs blackened, mostly starting at the new shoot
• Ink Spot: Dark round spots on leaves
• Marssonina Blight: Black spots on leaves with yellowish margins
• Aphids: Sucking insects on leaves; leaves are sticky and have a spotty glossy appearance 
• Powdery Mildew: White powdery material on upper or lower surface of leaf
• Chlorosis: Pale green or yellowish leaves 
• Poplar Twiggall Fly: Round swellings on twigs in various sizes and sometimes on main branches or stems 
• Oystershell Scale: Grayish or blackened colored scales, sometimes resembling sections of rice along mostly main stems and sometimes along branches and twigs
• Cytospora Canker: 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
• Bacterial Wetwood: Oozing liquid from wounds, sometimes white or frothy
•  What's Ailing Your Aspen?: Color photos of common Aspen problems

• Aphids: Insect sucking on leaves, sticky substance on leaves and flying insects around canopy
• Boxelder Bugs: Masses of reddish eggs on leaves or sometimes noticeable feeding on seeds or1/2" long bugs, mostly black with reddish lines and reddish abdomen, sometimes congregating in homes near windows

• Verticillium Wilt: Wilting or die-back of individual branches in tree, usually not entire tree

• Cherry Curculio: Puncture wounds in fruit
• Peach Tree Borer: Visible insect boring into tree, usually at or below soil line or noticeable die-back in canopy of tree or tree mostly looks stressed
• Cytospora Canker: 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
• Aphids: Insects on leaf surface and sometimes noticeably sticky residue on leaves

• Fall Webworm: Webbing formed around branches in canopy of tree

• Fall Webworm: Webbing formed around branches in canopy of tree
• Shoot Blight: Young leaves or small twigs blackened, mostly starting at the new shoot
• Marssonina Blight: Black spots on leaves with yellowish margins
• Septoria Leaf Spot: 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
• Ink Spot: Dark round spots on leaves
• Powdery Mildew: White powdery material on upper or lower surface of leaf
• Petiole-Gall Aphid: Swelling in leaf veins or leaf stems and sometimes hollow swellings on new growth
• Bacterial Wetwood: Oozing of liquid from trunk, often from wounds or branch crotches

• Apple Scab: Darkened spots or lesions on upper leaf surface
• Powdery Mildew: White powdery material on upper or lower surface of leaf
• Fire Blight: 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
• Chlorosis: Pale green or yellowish leaves

• Elm Leaf Beetle: Leaves skeletonized and holes chewed in leaves
• Elm leaf Miner: Leaves tunneled or leaves mined inside leaf surface
• Elm Flea Weevil: Leaves chewed through the entire leaf, sometimes in a shotgun pattern; some leaf mining may be visible
• European Elm Scale: 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
• Squirrel Damage: Smaller branches and twigs have bark missing in large sections
• Bacterial Wetwood: Oozing of liquid from trunk, often from wounds or branch crotches; will often appear grayish in color on elms

• Hackberry Nipplegall: Leaves with large raised bumps or nodules
• Eriophyid Mites: Twigs or branches deformed in to a dense mass of twigs often called a "witches broom"

• Fire Blight: 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
• Chlorosis: Pale green or yellowish leaves
• Pear Slug: Chewing or skeletonizing of leaves
• Rusts: Orange-yellow lesions on leaf surfaces and sometimes small light-colored projections on the underside of the lesion

• Honeylocust Plant Bug: Shortly after leaf emergence, new leaves are killed and older leaves may be distorted and discolored overall growth and canopy appears stunted
• Honeylocust Podgall Midge: Tree appears thin, usually seen with small pod or gall-like formations, typically best seen at the tips of branches
• Honeylocust Leafhopper: Small and slight flecking of foliage is visible, occasionally accompanied by sticky substance
• Honeylocust Spider Mite: Leaves discolor and turn orange-ish later in the summer and can prematurely drop
• Squirrel Damage: 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
• Cytospora Canker: 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
• Thyronectria Canker: Premature leaf drop and irregular shaped brown to black fruiting bodies on twigs, larger branches or stem

• Juniper Spittlebug: Frothy masses on needles
• Winter Desiccation: Needles bleached or brown
• Pruning Damage: Needles bleached or brown
• Vole Damage: Needles bleached or brown
• Spider Mite: Needles become discolored, usually with small flecks visible
• Juniper Rusts: Galls or gelatinous tissue formations on branches

• Cytospora Canker: 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

• Chlorosis: Pale green or yellowish leaves, particularly on Silver, Red, or Autumn Blaze Maples
• Aphids: Insects sucking on leaves, often associated with sticky substance on leaves
• Winter Sunscald: Large dead and discolored areas, usually on south to southwest side of trunk

• Fire Blight: 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

• Chlorosis: Pale green or yellowish leaves

• Peach Tree Borer: Burrowing into the trunk at or below surface line OR clear gum oozing from trunk, almost always at or near ground line
• Cytospora Canker: 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

• Pear Slug: Skeletonizing or chewing of leaves
• Fire Blight: 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
• Chlorosis: Pale green or yellowish leaves

• Mountain Pine Beetle: Whole Tree is faded out or bubble gum-looking residues are being pushed out from the trunk, primarily on Ponderosa, Scots or Pinyon
• Pinyon Pitch Mass Borer: On Pinyon, oozing pink or yellow pitch masses from the trunk
• Zimmerman Pine Moth: On Austrian, oozing popcorn-like masses or pitch, usually in the tops of the tree and usually near crotches

• Cooley Spruce Gall Adelgid: Ends of twigs and small branches have distorted growth and/or dieback from what appears to be a seed cone

• Anthracnose: Tree doesn't leaf out until late May or early June, leaves with blackened spotting or  witches broom with small dead branches

• Thousand Cankers Disease: Yellowing and thinning of the upper crown, wilting of foliage

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