Ash tree treatment in Greeley, CO

What treatment actually is

Protecting an ash from emerald ash borer means a systemic insecticide — a product the tree takes up and moves into the tissue where the larvae feed. It is not a spray on the outside of the bark. The larvae live under the bark, and surface applications do not reach them.

Three delivery methods are in general use:

• Trunk injection. Product introduced directly into the vascular system through small ports at the base of the trunk. The most reliable method for a large tree, and the one used for products that give multi-year protection. It does put small wounds in the trunk, which close over.
• Soil drench or soil injection. Applied at the root zone and taken up through the roots. Simpler, generally cheaper, but uptake depends on soil conditions and tree health — and in Greeley's compacted alkaline soils, uptake is less predictable than injection.
• Basal trunk spray. Applied to the lower trunk and absorbed through the bark. Convenient, but generally regarded as less reliable on larger trees.

Which trees are worth treating

The honest filter is fairly narrow, and a contractor who recommends treating every ash on a property is not applying it.

Good candidates: a healthy ash that has lost less than about a third of its canopy, has sound structure independent of the borer, is large enough that replacement would take decades, and sits somewhere it provides real value — shading a house, anchoring a front yard.

Poor candidates: a tree past roughly a third canopy loss, a tree with existing structural defects, a small ash where a replacement would catch up within a decade, or any tree where the treatment programme will not realistically be maintained. A lapsed programme ends the same way as no programme.

The full comparison, including how the money works out over time: treatment vs removal.

Timing

Treatments are generally applied in spring through early summer, when the tree is actively moving water and the product will translocate through the canopy. A tree treated in late autumn does not distribute the product effectively.

Products vary in how long they protect. Some are annual; the multi-year injectable products used in most professional programmes protect for around three years per treatment. Ask specifically which product is being used and what the re-treatment interval is, because that number is what determines the real cost over time.

The City of Greeley's residential program

Greeley has run a Residential Ash Treatment Program that gives private property owners access to a city-vetted, licensed pesticide applicator for preventative treatment, with a single treatment protecting a tree for around three years. Applications have historically run through the City's permit portal with a spring deadline and a summer treatment window.

For most homeowners with one or two ash trees, this is worth investigating before arranging anything privately. Contact Greeley Forestry on 970-351-5150 for the current year's programme, deadlines and eligibility.

What drives the cost

Treatment is priced by trunk diameter, because dose scales with the size of the tree. What moves the number:

• Trunk diameter at breast height. The primary variable. A 30-inch ash needs roughly three times the product of a 10-inch one.
• Method. Trunk injection costs more per application than a soil drench but generally lasts longer, so the cost per protected year can be lower.
• Product and interval. An annual product looks cheaper per visit and is not necessarily cheaper over five years than a three-year injectable.
• Number of trees. Several trees on one visit costs less per tree than a single call-out.
• Access. Minor for injection, more relevant for soil applications where equipment has to reach the root zone.

The comparison that matters is not treatment cost versus zero. It is treatment cost over the years you intend to keep the tree, against the cost of removing it — which rises sharply once the wood goes brittle. See ash tree removal.

Licensing

Commercial pesticide application in Colorado requires a state applicator licence. Anyone applying systemic insecticide on your property should hold one, and should tell you what product was used and any re-entry interval. Ask to see it.

Related

• Emerald ash borer in Greeley — where the pest stands locally
• Signs of emerald ash borer — confirm the diagnosis before treating
• Ash tree identification — make sure it is actually an ash
• Tree health consultation — if the decline may not be EAB at all

Questions we get about this

Does treatment actually work?

Yes, on the right tree, applied properly and maintained. Systemic insecticide protects an ash for as long as the treatment cycle continues. It is prevention and suppression rather than a cure, so a lapsed programme leaves the tree exposed again.

How often does an ash need re-treating?

It depends on the product. Some are annual; the multi-year injectable products used in most professional programmes protect for around three years. Ask which product is being used and what the interval is, because that determines the real long-term cost.

Can I treat my own ash tree?

Homeowner soil drench products exist, but uptake in Greeley's compacted alkaline soils is less predictable than professional trunk injection, and the concentrations available to homeowners are lower. For a large or valuable tree, professional application is the better bet.

Should I treat if EAB has not been found in Greeley?

That is the judgement call. The Colorado State Forest Service advises Front Range residents to assume the pest is in their city or town, and preventative treatment is more effective than treatment started after visible symptoms. For a large, valuable ash, waiting for confirmation is a gamble.

What does treatment cost?

It is priced by trunk diameter, method and product, so it varies widely between a small yard tree and a mature shade tree. Get it quoted per tree, and ask for the cost per protected year rather than per visit — that is the number that lets you compare options.

Is there a City program?

Greeley has run a Residential Ash Treatment Program giving property owners access to a city-vetted licensed applicator, with a single treatment protecting a tree for around three years. Contact Greeley Forestry on 970-351-5150 for the current year's details.