Tree health and disease in Grand Junction, CO
Find out why it looks wrong
Most sick trees in the Grand Valley have a stress problem first: too little water, too much water, or soil that locks up iron. Pests and cankers follow. Get a diagnosis before anyone sprays or cuts. CSU Extension can identify samples, and a tree service professional can treat or prune what needs it.
Start with the symptom
What you see, and what it may mean
This table is a starting point, not a diagnosis. Several of these look alike, and CSU warns that weed killer damage and nutrient problems can mimic chlorosis.
| What you see | Likely cause | Trees it often hits | First step |
|---|---|---|---|
| Yellow leaves with green veins, worst at branch tips | Iron chlorosis | Maples, pin and red oak, aspen, crabapple, pine, honeylocust | Check watering first, since overwatering often causes it. Test soil pH before buying iron |
| Dead branches with sunken or split bark, sometimes orange | Cytospora canker | Aspen, cottonwood and other poplars, peach, honeylocust, silver maple, Siberian elm | Fix the stress, usually drought or flooded roots, and prune dead limbs |
| Blackened leaves, twigs bent like a shepherd crook | Fire blight | Apple, pear and crabapple especially, also hawthorn and mountain ash | Prune infected wood. Minor cases can wait for the dormant season |
| Chewed leaves and fruit in summer, brown spots in the lawn | Japanese beetle | Over 300 plants, including fruit, shade and ornamental trees | Do not hang traps. Take a sample to CSU Extension |
| Thin ash crown, D-shaped holes, S-shaped tunnels | Emerald ash borer | Ash only, and white fringetree | Not confirmed in Mesa County. Report it. Read our ash plan |
| Young ash losing vigor, or with weak limbs | Lilac ash borer | Mostly ash under 8 inches across | One bark spray a year in mid to late May. Soil treatments do not work |
The usual root cause
Water first, spray later
CSU Extension says the primary control for cytospora is preventing stress, and that drought and flooding the roots are the two most common stresses. It says the same watering mistakes bring on iron chlorosis. In a valley where trees depend on irrigation, a watering fix is often the cheapest treatment you will ever buy.
The city suggests watering established trees every two to four weeks, deep enough to reach about 18 inches, where most roots live. Grass under the canopy competes for the same water, so CSU suggests replacing it with wood chip mulch on sensitive trees.
- Dig a small hole after watering to see how deep the water reached
- Keep spring watering in check, because wet springs make chlorosis worse
- Protect the trunk from mowers, since wounds let cankers in
- Avoid soil sterilant weed killers near root zones
Local rules
The city has a say in sick trees
Under Grand Junction Chapter 8.32, the City can inspect trees on private property for disease and insects and order you to treat or remove them, with an appeal to the Forestry Board within 10 days. Anyone spraying trees for hire needs a City license. Dead elm wood has its own transport rule.
- 01
Identify it
Take a sample in a hard container to CSU Extension at the Mesa County Fairgrounds, 2775 US 50, 970-244-1834.
- 02
Check who owns it
Right-of-way trees get free city care in Grand Junction. Our permit checker shows the rules for your town.
- 03
Choose the fix
Better watering, pruning, treatment or replacement. A tree service professional can tell you what is worth doing for this tree.
- 04
Replant smarter
If it has to go, pick something that suits the soil from our Grand Valley tree guide.
Short answers
Tree health questions, answered first
Short answers from CSU Extension, Mesa County and the City of Grand Junction.
Why are my tree leaves turning yellow?
In the Grand Valley the usual reason is iron chlorosis, caused by alkaline soil rather than missing iron. Newest leaves turn yellow while veins stay green. Overwatering makes it worse, so check your watering first. Nitrogen shortage looks different, yellowing older leaves first, including the veins. CSU has a full guide to look-alikes.
Can a sick tree be saved?
Often yes when the cause is stress and you catch it early, but not always. CSU says cytospora control starts with fixing stress such as drought or flooded roots, and pruning dead limbs helps. Heavy dieback may be too far gone. A tree service professional can look at how much of the tree is sound before you spend money on treatment.
Who can spray my tree in Grand Junction?
Inside city limits, anyone spraying trees for hire needs a City license from the Forestry Board. The City publishes its list of licensed tree companies, and it shows who is approved for chemical application. You can treat your own tree if you follow the product label, though large trees are hard to treat without equipment.
Do I need to treat my ash for emerald ash borer now?
It has not been confirmed in Mesa County, so this is a plan to make rather than an emergency. The Colorado State Forest Service lists Carbondale as the only confirmed spot in western Colorado. Decide whether your tree is worth treating when the pest arrives. Our tree guide walks through treating or replacing.
Is there a free place to get a tree problem identified?
CSU Extension in Mesa County identifies samples and takes suspected Japanese beetles at the fairgrounds. Bring insects in a hard container to 2775 US 50 or call 970-244-1834. Ask first about what they need for leaves and branches. For trees in the Grand Junction right-of-way, the City provides care at no charge.
Sources
Where this came from
We read each page below on November 3, 2026. Treatment names come from CSU and are not product endorsements, so follow the label or hire a licensed applicator.
- Iron Chlorosis of Woody Plants . CSU Extension.
Symptoms, look-alikes, watering, mulch and iron treatments.
Accessed - Cytospora Canker . CSU Extension.
Hosts, symptoms and stress prevention.
Accessed - Fire Blight . CSU Extension.
Hosts, symptoms, how it spreads and dormant season pruning.
Accessed - PlantTalk 1769: Ash Care . CSU Extension PlantTalk.
Lilac ash borer timing and treatment.
Accessed - Japanese Beetle Eradication . Mesa County.
Host range, trap advice and where to take samples.
Accessed - Emerald Ash Borer: A Green Menace . Colorado State Forest Service.
Where emerald ash borer has been confirmed.
Accessed - Chapter 8.32 Trees . City of Grand Junction, 2019 copy via Colorado Tree Coalition.
Inspection, orders, appeals, licensing and elm wood. An older copy, so confirm the current text with the City.
Accessed - General Tree Care Information . City of Grand Junction.
Watering schedule and root depth.
Accessed
Send the details
Something off with your tree?
Send a photo of the whole tree and a close-up of the problem. A tree service professional can tell you what they see and what it would cost to deal with it.
What happens next
- 1 Send the details What the tree is doing, where it is, and a photo or two if you have them.
- 2 We follow up You hear back the way you asked, with next steps.
- 3 Price in writing You see it before a saw starts, and the yes or no stays with you.
What helps us price it
- A photo of the whole tree and one of the problem
- Roughly how tall it is and how thick the trunk is
- What it could hit: a roof, a fence or power lines
- How a truck gets there, and how wide your gate is
- Whether you also want the stump ground and the wood hauled
If a tree is on a power line or anyone is hurt, call 911 or your electric utility first.
More tree services across the valley
Tree removal
Dead, leaning or too close to the house.
Tree trimming and pruning
Deadwood, heavy limbs and clearance.
Stump grinding
Ground below grade, ready to replant.
Storm and emergency tree service
Who to call first, and what comes next.
Cabling and bracing
Support for a weak fork or a heavy limb.
Land clearing
Lots, brush, Russian olive and tamarisk.
Wildfire mitigation
Thinning and cleanup around the home.
Guides and tools: Grand Valley tree guide, Tree permit and HOA checker, Tree removal cost estimator, Storm alerts and damage help.